MINOR: mux_quic: remove duplicate QMux local transport params

When QMux was first implemented, values used for emitted transport
parameters in xprt_qstrm and local flow control in mux_quic were
initialized separately. This is error prone in particular if a value is
change in one layer but not the other.

This patch fixes this by using xprt_qstrm_lparams() in QMux init
function. Mux flow control is then loaded with these values. Thus all
values are now initialized in a single place which is xprt_qstrm_init().

.github/actions/setup-vtest/action.yml

@@ -20,10 +20,24 @@ runs:
         ulimit -n 65536
         ulimit -c unlimited
 
-    - name: Install VTest
+    - name: Get VTest latest commit SHA
+      id: vtest-sha
       shell: bash
       run: |
-        scripts/build-vtest.sh
+        echo "sha=$(git ls-remote https://code.vinyl-cache.org/vtest/VTest2 HEAD | cut -f1)" >> $GITHUB_OUTPUT
+
+    - name: Cache VTest
+      id: cache-vtest
+      uses: actions/cache@v5
+      with:
+        path: ${{ github.workspace }}/vtest
+        key: vtest-${{ runner.os }}-${{ runner.arch }}-${{ steps.vtest-sha.outputs.sha }}
+
+    - name: Install VTest
+      if: ${{ steps.cache-vtest.outputs.cache-hit != 'true' }}
+      shell: bash
+      run: |
+        DESTDIR=${{ github.workspace }}/vtest scripts/build-vtest.sh
 
     - name: Install problem matcher for VTest
       shell: bash

.github/matrix.py

@@ -12,6 +12,7 @@ import functools
 import json
 import re
 import sys
+import urllib.error
 import urllib.request
 from os import environ
 from packaging import version
@@ -33,13 +34,24 @@ def get_all_github_tags(url):
     headers = {}
     if environ.get("GITHUB_TOKEN") is not None:
         headers["Authorization"] = "token {}".format(environ.get("GITHUB_TOKEN"))
-    request = urllib.request.Request(url, headers=headers)
+    all_tags = []
-    try:
+    page = 1
-        tags = urllib.request.urlopen(request)
+    sep = "&" if "?" in url else "?"
-    except:
+    while True:
-        return None
+        paginated_url = "{}{}per_page=100&page={}".format(url, sep, page)
-    tags = json.loads(tags.read().decode("utf-8"))
+        request = urllib.request.Request(paginated_url, headers=headers)
-    return [tag['name'] for tag in tags]
+        try:
+            response = urllib.request.urlopen(request)
+        except urllib.error.URLError:
+            return all_tags if all_tags else None
+        tags = json.loads(response.read().decode("utf-8"))
+        if not tags:
+            break
+        all_tags.extend([tag['name'] for tag in tags])
+        if len(tags) < 100:
+            break
+        page += 1
+    return all_tags if all_tags else None
 
 @functools.lru_cache(5)
 def determine_latest_openssl(ssl):
@@ -57,7 +69,7 @@ def aws_lc_version_string_to_num(version_string):
     return tuple(map(int, version_string[1:].split('.')))
 
 def aws_lc_version_valid(version_string):
-    return re.match('^v[0-9]+(\.[0-9]+)*$', version_string)
+    return re.match(r'^v[0-9]+(\.[0-9]+)*$', version_string)
 
 @functools.lru_cache(5)
 def determine_latest_aws_lc(ssl):
@@ -65,6 +77,8 @@ def determine_latest_aws_lc(ssl):
     if not tags:
         return "AWS_LC_VERSION=failed_to_detect"
     valid_tags = list(filter(aws_lc_version_valid, tags))
+    if not valid_tags:
+        return "AWS_LC_VERSION=failed_to_detect"
     latest_tag = max(valid_tags, key=aws_lc_version_string_to_num)
     return "AWS_LC_VERSION={}".format(latest_tag[1:])
 
@@ -72,15 +86,16 @@ def aws_lc_fips_version_string_to_num(version_string):
     return tuple(map(int, version_string[12:].split('.')))
 
 def aws_lc_fips_version_valid(version_string):
-    return re.match('^AWS-LC-FIPS-[0-9]+(\.[0-9]+)*$', version_string)
+    return re.match(r'^AWS-LC-FIPS-[0-9]+(\.[0-9]+)*$', version_string)
 
 @functools.lru_cache(5)
 def determine_latest_aws_lc_fips(ssl):
-    # the AWS-LC-FIPS tags are at the end of the list, so let's get a lot
+    tags = get_all_github_tags("https://api.github.com/repos/aws/aws-lc/tags")
-    tags = get_all_github_tags("https://api.github.com/repos/aws/aws-lc/tags?per_page=200")
     if not tags:
         return "AWS_LC_FIPS_VERSION=failed_to_detect"
     valid_tags = list(filter(aws_lc_fips_version_valid, tags))
+    if not valid_tags:
+        return "AWS_LC_FIPS_VERSION=failed_to_detect"
     latest_tag = max(valid_tags, key=aws_lc_fips_version_string_to_num)
     return "AWS_LC_FIPS_VERSION={}".format(latest_tag[12:])
 
@@ -88,7 +103,7 @@ def wolfssl_version_string_to_num(version_string):
     return tuple(map(int, version_string[1:].removesuffix('-stable').split('.')))
 
 def wolfssl_version_valid(version_string):
-    return re.match('^v[0-9]+(\.[0-9]+)*-stable$', version_string)
+    return re.match(r'^v[0-9]+(\.[0-9]+)*-stable$', version_string)
 
 @functools.lru_cache(5)
 def determine_latest_wolfssl(ssl):

.github/workflows/aws-lc-fips.yml

@@ -1,12 +0,0 @@
-name: AWS-LC-FIPS
-
-on:
-  schedule:
-    - cron: "0 0 * * 4"
-  workflow_dispatch:
-
-jobs:
-  test:
-    uses: ./.github/workflows/aws-lc-template.yml
-    with:
-      command: "from matrix import determine_latest_aws_lc_fips; print(determine_latest_aws_lc_fips(''))"

.github/workflows/aws-lc-template.yml

@@ -1,94 +0,0 @@
-name: AWS-LC template
-
-on:
-  workflow_call:
-    inputs:
-      command:
-        required: true
-        type: string
-
-permissions:
-  contents: read
-
-jobs:
-  test:
-    runs-on: ubuntu-latest
-    if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
-    steps:
-      - uses: actions/checkout@v5
-      - name: Determine latest AWS-LC release
-        id: get_aws_lc_release
-        run: |
-          result=$(cd .github && python3  -c "${{ inputs.command }}")
-          echo $result
-          echo "result=$result" >> $GITHUB_OUTPUT
-      - name: Cache AWS-LC
-        id: cache_aws_lc
-        uses: actions/cache@v4
-        with:
-          path: '~/opt/'
-          key: ssl-${{ steps.get_aws_lc_release.outputs.result }}-Ubuntu-latest-gcc
-      - name: Install apt dependencies
-        run: |
-          sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none
-          sudo apt-get --no-install-recommends -y install socat gdb jose
-      - name: Install AWS-LC
-        if: ${{ steps.cache_ssl.outputs.cache-hit != 'true' }}
-        run: env ${{ steps.get_aws_lc_release.outputs.result }} scripts/build-ssl.sh
-      - name: Compile HAProxy
-        run: |
-          make -j$(nproc) ERR=1 CC=gcc TARGET=linux-glibc \
-            USE_OPENSSL_AWSLC=1 USE_QUIC=1 \
-            SSL_LIB=${HOME}/opt/lib SSL_INC=${HOME}/opt/include \
-            DEBUG="-DDEBUG_POOL_INTEGRITY -DDEBUG_UNIT" \
-            ADDLIB="-Wl,-rpath,/usr/local/lib/ -Wl,-rpath,$HOME/opt/lib/"
-          sudo make install
-      - name: Show HAProxy version
-        id: show-version
-        run: |
-          ldd $(which haproxy)
-          haproxy -vv
-          echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
-      - uses: ./.github/actions/setup-vtest
-      - name: Run VTest for HAProxy
-        id: vtest
-        run: |
-          make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
-      - name: Run Unit tests
-        id: unittests
-        run: |
-          make unit-tests
-      - name: Show VTest results
-        if: ${{ failure() && steps.vtest.outcome == 'failure' }}
-        run: |
-          for folder in ${TMPDIR:-/tmp}/haregtests-*/vtc.*; do
-            printf "::group::"
-            cat $folder/INFO
-            cat $folder/LOG
-            echo "::endgroup::"
-          done
-          exit 1
-      - name: Show coredumps
-        if: ${{ failure() && steps.vtest.outcome == 'failure' }}
-        run: |
-          failed=false
-          shopt -s nullglob
-          for file in /tmp/core.*; do
-            failed=true
-            printf "::group::"
-            gdb -ex 'thread apply all bt full' ./haproxy $file
-            echo "::endgroup::"
-          done
-          if [ "$failed" = true ]; then
-            exit 1;
-          fi
-      - name: Show Unit-Tests results
-        if: ${{ failure() && steps.unittests.outcome == 'failure' }}
-        run: |
-          for result in ${TMPDIR:-/tmp}/ha-unittests-*/results/res.*; do
-            printf "::group::"
-            cat $result
-            echo "::endgroup::"
-          done
-          exit 1
-

.github/workflows/aws-lc.yml

@@ -5,8 +5,95 @@ on:
     - cron: "0 0 * * 4"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
-  test:
+  Test:
-    uses: ./.github/workflows/aws-lc-template.yml
+    name: ${{ matrix.name }}
-    with:
+    runs-on: ubuntu-latest
-      command: "from matrix import determine_latest_aws_lc; print(determine_latest_aws_lc(''))"
+    strategy:
+      matrix:
+        include:
+          - name: AWS-LC
+            command: "from matrix import determine_latest_aws_lc; print(determine_latest_aws_lc(''))"
+          - name: AWS-LC (FIPS)
+            command: "from matrix import determine_latest_aws_lc_fips; print(determine_latest_aws_lc_fips(''))"
+    if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
+    steps:
+      - uses: actions/checkout@v6
+      - name: Determine latest AWS-LC release
+        id: get_aws_lc_release
+        run: |
+          result=$(cd .github && python3  -c "${{ matrix.command }}")
+          echo $result
+          echo "result=$result" >> $GITHUB_OUTPUT
+      - name: Cache AWS-LC
+        id: cache_aws_lc
+        uses: actions/cache@v5
+        with:
+          path: '~/opt/'
+          key: ssl-${{ steps.get_aws_lc_release.outputs.result }}-Ubuntu-latest-gcc
+      - name: Install apt dependencies
+        run: |
+          sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none
+          sudo apt-get --no-install-recommends -y install socat gdb jose
+      - name: Install AWS-LC
+        if: ${{ steps.cache_ssl.outputs.cache-hit != 'true' }}
+        run: env ${{ steps.get_aws_lc_release.outputs.result }} scripts/build-ssl.sh
+      - name: Compile HAProxy
+        run: |
+          make -j$(nproc) ERR=1 CC=gcc TARGET=linux-glibc \
+            USE_OPENSSL_AWSLC=1 USE_QUIC=1 \
+            SSL_LIB=${HOME}/opt/lib SSL_INC=${HOME}/opt/include \
+            DEBUG="-DDEBUG_POOL_INTEGRITY -DDEBUG_UNIT" \
+            ADDLIB="-Wl,-rpath,/usr/local/lib/ -Wl,-rpath,$HOME/opt/lib/"
+          sudo make install
+      - name: Show HAProxy version
+        id: show-version
+        run: |
+          ldd $(which haproxy)
+          haproxy -vv
+          echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
+      - uses: ./.github/actions/setup-vtest
+      - name: Run VTest for HAProxy
+        id: vtest
+        run: |
+          make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
+      - name: Run Unit tests
+        id: unittests
+        run: |
+          make unit-tests
+      - name: Show VTest results
+        if: ${{ failure() && steps.vtest.outcome == 'failure' }}
+        run: |
+          for folder in ${TMPDIR:-/tmp}/haregtests-*/vtc.*; do
+            printf "::group::"
+            cat $folder/INFO
+            cat $folder/LOG
+            echo "::endgroup::"
+          done
+          exit 1
+      - name: Show coredumps
+        if: ${{ failure() && steps.vtest.outcome == 'failure' }}
+        run: |
+          failed=false
+          shopt -s nullglob
+          for file in /tmp/core.*; do
+            failed=true
+            printf "::group::"
+            gdb -ex 'thread apply all bt full' ./haproxy $file
+            echo "::endgroup::"
+          done
+          if [ "$failed" = true ]; then
+            exit 1;
+          fi
+      - name: Show Unit-Tests results
+        if: ${{ failure() && steps.unittests.outcome == 'failure' }}
+        run: |
+          for result in ${TMPDIR:-/tmp}/ha-unittests-*/results/res.*; do
+            printf "::group::"
+            cat $result
+            echo "::endgroup::"
+          done
+          exit 1

.github/workflows/codespell.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: codespell-project/codespell-problem-matcher@v1.2.0
     - uses: codespell-project/actions-codespell@master
       with:

.github/workflows/compliance.yml

@@ -14,7 +14,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Install h2spec
       id: install-h2spec
       run: |
@@ -45,7 +45,7 @@ jobs:
         fi
         echo "::endgroup::"
         haproxy -vv
-        echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+        echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
     - name: Launch HAProxy ${{ steps.show-version.outputs.version }}
       run: haproxy -f .github/h2spec.config -D
     - name: Run h2spec ${{ steps.install-h2spec.outputs.version }}

.github/workflows/contrib.yml

@@ -10,7 +10,7 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Compile dev/flags/flags
       run: |
         make dev/flags/flags

.github/workflows/coverity.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Install apt dependencies
       run: |
         sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none

.github/workflows/cross-zoo.yml

@@ -99,7 +99,7 @@ jobs:
         sudo apt-get -yq --force-yes install \
             gcc-${{ matrix.platform.arch }} \
             ${{ matrix.platform.libs }}
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
 
 
     - name: install quictls

.github/workflows/fedora-rawhide.yml

@@ -25,7 +25,7 @@ jobs:
     container:
       image: fedora:rawhide
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Install dependencies
       run: |
         dnf -y install awk diffutils git pcre-devel zlib-devel pcre2-devel 'perl(FindBin)' perl-IPC-Cmd 'perl(File::Copy)' 'perl(File::Compare)' lua-devel socat findutils systemd-devel clang openssl-devel.x86_64
@@ -48,7 +48,7 @@ jobs:
         ldd $(command -v haproxy)
         echo "::endgroup::"
         haproxy -vv
-        echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+        echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
 #
 # TODO: review this workaround later
     - name: relax crypto policies
@@ -59,7 +59,7 @@ jobs:
     - name: Run VTest for HAProxy ${{ steps.show-version.outputs.version }}
       id: vtest
       run: |
-        make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+        make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
     - name: Show VTest results
       if: ${{ failure() && steps.vtest.outcome == 'failure' }}
       run: |

.github/workflows/illumos.yml

@@ -5,15 +5,16 @@ on:
     - cron: "0 0 25 * *"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   gcc:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
-    permissions:
-      contents: read
     steps:
       - name: "Checkout repository"
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: "Build on VM"
         uses: vmactions/solaris-vm@v1

.github/workflows/musl.yml

@@ -20,11 +20,10 @@ jobs:
         run: |
           ulimit -c unlimited
           echo '/tmp/core/core.%h.%e.%t' > /proc/sys/kernel/core_pattern
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install dependencies
         run: apk add gcc gdb make tar git python3 libc-dev linux-headers pcre-dev pcre2-dev openssl-dev lua5.3-dev grep socat curl musl-dbg lua5.3-dbg jose
-      - name: Install VTest
+      - uses: ./.github/actions/setup-vtest
-        run: scripts/build-vtest.sh
       - name: Build
         run: make -j$(nproc) TARGET=linux-musl DEBUG="-DDEBUG_POOL_INTEGRITY -DDEBUG_UNIT" ARCH_FLAGS='-ggdb3' CC=cc V=1 USE_LUA=1 LUA_INC=/usr/include/lua5.3 LUA_LIB=/usr/lib/lua5.3 USE_OPENSSL=1 USE_PCRE2=1 USE_PCRE2_JIT=1 USE_PROMEX=1
       - name: Show version
@@ -36,7 +35,7 @@ jobs:
         run: echo "::add-matcher::.github/vtest.json"
       - name: Run VTest
         id: vtest
-        run: make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+        run: make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
       - name: Run Unit tests
         id: unittests
         run: |

.github/workflows/netbsd.yml

@@ -5,15 +5,16 @@ on:
     - cron: "0 0 25 * *"
   workflow_dispatch:
 
+permissions:
+  contents: read
+
 jobs:
   gcc:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
-    permissions:
-      contents: read
     steps:
       - name: "Checkout repository"
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: "Build on VM"
         uses: vmactions/netbsd-vm@v1

.github/workflows/openssl-ech.yml

@@ -13,15 +13,13 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
-      - name: Install VTest
-        run: |
-          scripts/build-vtest.sh
       - name: Install apt dependencies
         run: |
           sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none
           sudo apt-get --no-install-recommends -y install socat gdb
           sudo apt-get --no-install-recommends -y install libpsl-dev
+      - uses: ./.github/actions/setup-vtest
       - name: Install OpenSSL+ECH
         run: env OPENSSL_VERSION="git-feature/ech" GIT_TYPE="branch" scripts/build-ssl.sh
       - name: Install curl+ECH
@@ -40,7 +38,7 @@ jobs:
         run: |
           ldd $(which haproxy)
           haproxy -vv
-          echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+          echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
       - name: Install problem matcher for VTest
         run: echo "::add-matcher::.github/vtest.json"
       - name: Run VTest for HAProxy
@@ -51,7 +49,7 @@ jobs:
           ulimit -n 65536
           # allow to catch coredumps
           ulimit -c unlimited
-          make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+          make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
       - name: Show VTest results
         if: ${{ failure() && steps.vtest.outcome == 'failure' }}
         run: |

.github/workflows/openssl-master.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install apt dependencies
         run: |
           sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none
@@ -35,7 +35,7 @@ jobs:
         run: |
           ldd $(which haproxy)
           haproxy -vv
-          echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+          echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
       - name: Install problem matcher for VTest
         run: echo "::add-matcher::.github/vtest.json"
       - name: Run VTest for HAProxy
@@ -46,7 +46,7 @@ jobs:
           ulimit -n 65536
           # allow to catch coredumps
           ulimit -c unlimited
-          make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+          make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
       - name: Show VTest results
         if: ${{ failure() && steps.vtest.outcome == 'failure' }}
         run: |

.github/workflows/quic-interop-aws-lc.yml

@@ -9,17 +9,16 @@ on:
   schedule:
     - cron: "0 0 * * 2"
 
+permissions:
+  contents: read
 
 jobs:
   combined-build-and-run:
     runs-on: ubuntu-24.04
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
-    permissions:
-      contents: read
-      packages: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Update Docker to the latest
         uses: docker/setup-docker-action@v4
@@ -50,7 +49,7 @@ jobs:
           python run.py -j result.json -l logs-ngtcp2 -r haproxy=local:aws-lc -t "handshake,transfer,longrtt,chacha20,multiplexing,retry,resumption,zerortt,http3,blackhole,keyupdate,ecn,amplificationlimit,handshakeloss,transferloss,handshakecorruption,transfercorruption,ipv6,v2" -c ngtcp2 -s haproxy
 
       - name: Delete succeeded logs
-        if: failure()
+        if: ${{ failure() }}
         run: |
           for client in chrome picoquic quic-go ngtcp2; do
             pushd quic-interop-runner/logs-${client}/haproxy_${client}
@@ -59,7 +58,7 @@ jobs:
           done
 
       - name: Logs upload
-        if: failure()
+        if: ${{ failure() }}
         uses: actions/upload-artifact@v4
         with:
           name: logs

.github/workflows/quic-interop-libressl.yml

@@ -9,17 +9,16 @@ on:
   schedule:
     - cron: "0 0 * * 2"
 
+permissions:
+  contents: read
 
 jobs:
   combined-build-and-run:
     runs-on: ubuntu-24.04
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
-    permissions:
-      contents: read
-      packages: write
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Update Docker to the latest
         uses: docker/setup-docker-action@v4
@@ -48,7 +47,7 @@ jobs:
           python run.py -j result.json -l logs-quic-go -r haproxy=local:libressl -t "handshake,transfer,longrtt,chacha20,multiplexing,retry,http3,blackhole,amplificationlimit,transferloss,transfercorruption,v2" -c quic-go -s haproxy
 
       - name: Delete succeeded logs
-        if: failure()
+        if: ${{ failure() }}
         run: |
           for client in picoquic quic-go; do
             pushd quic-interop-runner/logs-${client}/haproxy_${client}
@@ -57,7 +56,7 @@ jobs:
           done
 
       - name: Logs upload
-        if: failure()
+        if: ${{ failure() }}
         uses: actions/upload-artifact@v4
         with:
           name: logs

.github/workflows/quictls.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install apt dependencies
         run: |
           sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none
@@ -38,12 +38,12 @@ jobs:
         run: |
           ldd $(which haproxy)
           haproxy -vv
-          echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+          echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
       - uses: ./.github/actions/setup-vtest
       - name: Run VTest for HAProxy
         id: vtest
         run: |
-          make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+          make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
       - name: Show VTest results
         if: ${{ failure() && steps.vtest.outcome == 'failure' }}
         run: |

.github/workflows/vtest.yml

@@ -23,7 +23,7 @@ jobs:
     outputs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Generate Build Matrix
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -44,7 +44,7 @@ jobs:
       TMPDIR: /tmp
       OT_CPP_VERSION: 1.6.0
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 100
 
@@ -59,7 +59,7 @@ jobs:
     - name: Cache SSL libs
       if: ${{ matrix.ssl && matrix.ssl != 'stock' && matrix.ssl != 'BORINGSSL=yes' && !contains(matrix.ssl, 'QUICTLS') }}
       id: cache_ssl
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: '~/opt/'
         key: ssl-${{ steps.generate-cache-key.outputs.key }}
@@ -67,7 +67,7 @@ jobs:
     - name: Cache OpenTracing
       if: ${{ contains(matrix.FLAGS, 'USE_OT=1') }}
       id: cache_ot
-      uses: actions/cache@v4
+      uses: actions/cache@v5
       with:
         path: '~/opt-ot/'
         key: ${{ matrix.os }}-ot-${{ matrix.CC }}-${{ env.OT_CPP_VERSION }}-${{ contains(matrix.name, 'ASAN') }}
@@ -136,11 +136,11 @@ jobs:
         fi
         echo "::endgroup::"
         haproxy -vv
-        echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+        echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
     - name: Run VTest for HAProxy ${{ steps.show-version.outputs.version }}
       id: vtest
       run: |
-        make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+        make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
     - name: Show VTest results
       if: ${{ failure() && steps.vtest.outcome == 'failure' }}
       run: |

.github/workflows/windows.yml

@@ -36,7 +36,7 @@ jobs:
           - USE_THREAD=1
           - USE_ZLIB=1
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - uses: msys2/setup-msys2@v2
       with:
         install: >-

.github/workflows/wolfssl.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository_owner == 'haproxy' || github.event_name == 'workflow_dispatch' }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Install apt dependencies
         run: |
           sudo apt-get update -o Acquire::Languages=none -o Acquire::Translation=none
@@ -34,12 +34,12 @@ jobs:
         run: |
           ldd $(which haproxy)
           haproxy -vv
-          echo "version=$(haproxy -v |awk 'NR==1{print $3}')" >> $GITHUB_OUTPUT
+          echo "version=$(haproxy -vq)" >> $GITHUB_OUTPUT
       - uses: ./.github/actions/setup-vtest
       - name: Run VTest for HAProxy
         id: vtest
         run: |
-          make reg-tests VTEST_PROGRAM=../vtest/vtest REGTESTS_TYPES=default,bug,devel
+          make reg-tests VTEST_PROGRAM=${{ github.workspace }}/vtest/vtest REGTESTS_TYPES=default,bug,devel
       - name: Run Unit tests
         id: unittests
         run: |

CHANGELOG

@@ -1,6 +1,167 @@
 ChangeLog :
 ===========
 
+2026/04/03 : 3.4-dev8
+    - MINOR: log: split do_log() in do_log() + do_log_ctx()
+    - MINOR: log: provide a way to override logger->profile from process_send_log_ctx
+    - MINOR: log: support optional 'profile <log_profile_name>' argument to do-log action
+    - BUG/MINOR: sock: adjust accept() error messages for ENFILE and ENOMEM
+    - BUG/MINOR: qpack: fix 62-bit overflow and 1-byte OOB reads in decoding
+    - MEDIUM: sched: do not run a same task multiple times in series
+    - MINOR: sched: do not requeue a tasklet into the current queue
+    - MINOR: sched: do not punish self-waking tasklets anymore
+    - MEDIUM: sched: do not punish self-waking tasklets if TASK_WOKEN_ANY
+    - MEDIUM: sched: change scheduler budgets to lower TL_BULK
+    - MINOR: mux-h2: assign a limited frames processing budget
+    - BUILD: sched: fix leftover of debugging test in single-run changes
+    - BUG/MEDIUM: acme: fix multiple resource leaks in acme_x509_req()
+    - MINOR: http_htx: use enum for arbitrary values in conf_errors
+    - MINOR: http_htx: rename fields in struct conf_errors
+    - MINOR: http_htx: split check/init of http_errors
+    - MINOR/OPTIM: http_htx: lookup once http_errors section on check/init
+    - MEDIUM: proxy: remove http-errors limitation for dynamic backends
+    - BUG/MINOR: acme: leak of ext_san upon insertion error
+    - BUG/MINOR: acme: wrong error when checking for duplicate section
+    - BUG/MINOR: acme/cli: wrong argument check in 'acme renew'
+    - BUG/MINOR: http_htx: fix null deref in http-errors config check
+    - MINOR: buffers: Move small buffers management from quic to dynbuf part
+    - MINOR: dynbuf: Add helper functions to alloc large and small buffers
+    - MINOR: quic: Use b_alloc_small() to allocate a small buffer
+    - MINOR: config: Relax tests on the configured size of small buffers
+    - MINOR: config: Report the warning when invalid large buffer size is set
+    - MEDIUM: htx: Add htx_xfer function to replace htx_xfer_blks
+    - MINOR: htx: Add helper functions to xfer a message to smaller or larger one
+    - MINOR: http-ana: Use HTX API to move to a large buffer
+    - MEDIUM: chunk: Add support for small chunks
+    - MEDIUM: stream: Try to use a small buffer for HTTP request on queuing
+    - MEDIUM: stream: Try to use small buffer when TCP stream is queued
+    - MEDIUM: stconn: Use a small buffer if possible for L7 retries
+    - MEDIUM: tree-wide: Rely on htx_xfer() instead of htx_xfer_blks()
+    - Revert "BUG/MEDIUM: mux-h2: make sure to always report pending errors to the stream"
+    - MEDIUM: mux-h2: Stop dealing with HTX flags transfer in h2_rcv_buf()
+    - MEDIUM: tcpcheck: Use small buffer if possible for healthchecks
+    - MINOR: proxy: Review options flags used to configure healthchecks
+    - DOC: config: Fix alphabetical ordering of proxy options
+    - DOC: config: Fix alphabetical ordering of external-check directives
+    - MINOR: proxy: Add use-small-buffers option to set where to use small buffers
+    - DOC: config: Add missing 'status-code' param for 'http-check expect' directive
+    - DOC: config: Reorder params for 'tcp-check expect' directive
+    - BUG/MINOR: acme: NULL check on my_strndup()
+    - BUG/MINOR: acme: free() DER buffer on a2base64url error path
+    - BUG/MINOR: acme: replace atol with len-bounded __strl2uic() for retry-after
+    - BUG/MINOR: acme/cli: fix argument check and error in 'acme challenge_ready'
+    - BUILD: tools: potential null pointer dereference in dl_collect_libs_cb
+    - BUG/MINOR: ech: permission checks on the CLI
+    - BUG/MINOR: acme: permission checks on the CLI
+    - BUG/MEDIUM: check: Don't reuse the server xprt if we should not
+    - MINOR: checks: Store the protocol to be used in struct check
+    - MINOR: protocols: Add a new proto_is_quic() function
+    - MEDIUM: connections: Enforce mux protocol requirements
+    - MEDIUM: server: remove a useless memset() in srv_update_check_addr_port.
+    - BUG/MINOR: config: Warn only if warnif_cond_conflicts report a conflict
+    - BUG/MINOR: config: Properly test warnif_misplaced_* return values
+    - BUG/MINOR: http-ana: Only consider client abort for abortonclose
+    - BUG/MEDIUM: acme: skip doing challenge if it is already valid
+    - MINOR: connections: Enhance tune.idle-pool.shared
+    - BUG/MINOR: acme: fix task allocation leaked upon error
+    - BUG/MEDIUM: htx: Fix htx_xfer() to consume more data than expected
+    - CI: github: fix tag listing by implementing proper API pagination
+    - CLEANUP: fix typos and spelling in comments and documentation
+    - BUG/MINOR: quic: close conn on packet reception with incompatible frame
+    - CLEANUP: stconn: Remove usless sc_new_from_haterm() declaration
+    - BUG/MINOR: stconn: Always declare the SC created from healthchecks as a back SC
+    - MINOR: stconn: flag the stream endpoint descriptor when the app has started
+    - MINOR: mux-h2: report glitches on early RST_STREAM
+    - BUG/MINOR: net_helper: fix length controls on ip.fp tcp options parsing
+    - BUILD: net_helper: fix unterminated comment that broke the build
+    - MINOR: resolvers: basic TXT record implementation
+    - MINOR: acme: store the TXT record in auth->token
+    - MEDIUM: acme: add dns-01 DNS propagation pre-check
+    - MEDIUM: acme: new 'challenge-ready' option
+    - DOC: configuration: document challenge-ready and dns-delay options for ACME
+    - SCRIPTS: git-show-backports: list new commits and how to review them with -L
+    - BUG/MEDIUM: ssl/cli: tls-keys commands warn when accessed without admin level
+    - BUG/MEDIUM: ssl/ocsp: ocsp commands warn when accessed without admin level
+    - BUG/MEDIUM: map/cli: map/acl commands warn when accessed without admin level
+    - BUG/MEDIUM: ssl/cli: tls-keys commands are missing permission checks
+    - BUG/MEDIUM: ssl/ocsp: ocsp commands are missing permission checks
+    - BUG/MEDIUM: map/cli: CLI commands lack admin permission checks
+    - DOC: configuration: mention QUIC server support
+    - MEDIUM: Add set-headers-bin, add-headers-bin and del-headers-bin actions
+    - BUG/MEDIUM: mux-h1: Don't set MSG_MORE on bodyless responses forwarded to client
+    - BUG/MINOR: http_act: Properly handle decoding errors in *-headers-bin actions
+    - MEDIUM: stats: Hide the version by default and add stats-showversion
+    - MINOR: backends: Don't update last_sess if it did not change
+    - MINOR: servers: Don't update last_sess if it did not change
+    - MINOR: ssl/log: add keylog format variables and env vars
+    - DOC: configuration: update tune.ssl.keylog URL to IETF draft
+    - BUG/MINOR: http_act: Make set/add-headers-bin compatible with ACL conditions
+    - MINOR: action: Add a sample expression field in arguments used by HTTP actions
+    - MEDIUM: http_act: Rework *-headers-bin actions
+    - BUG/MINOR: tcpcheck: Remove unexpected flag on tcpcheck rules for httchck option
+    - MEDIUM: tcpcheck: Refactor how tcp-check rulesets are stored
+    - MINOR: tcpcheck: Deal with disable-on-404 and send-state in the tcp-check itself
+    - BUG/MINOR: tcpcheck: Don't enable http_needed when parsing HTTP samples
+    - MINOR: tcpcheck: Use tcpcheck flags to know a healthcheck uses SSL connections
+    - BUG/MINOR: tcpcheck: Use tcpcheck context for expressions parsing
+    - CLEANUP: tcpcheck: Don't needlessly expose proxy_parse_tcpcheck()
+    - MINOR: tcpcheck: Add a function to stringify the healthcheck type
+    - MEDIUM: tcpcheck: Split parsing functions to prepare healthcheck sections parsing
+    - MEDIUM: tcpcheck:  Add parsing support for healthcheck sections
+    - MINOR: tcpcheck: Extract tcpheck ruleset post-config in a dedicated function
+    - MEDIUM: tcpcheck/server: Add healthcheck server keyword
+    - REGTESTS: tcpcheck: Add a script to check healthcheck section
+    - MINOR: acme: add 'dns-timeout' keyword for dns-01 challenge
+    - CLEANUP: net_helper: fix typo in comment
+    - MINOR: acme: set the default dns-delay to 30s
+    - MINOR: connection: add function to identify a QUIC connection
+    - MINOR: quic: refactor frame parsing
+    - MINOR: quic: refactor frame encoding
+    - BUG/MINOR: quic: fix documentation for transport params decoding
+    - MINOR: quic: split transport params decoding/check
+    - MINOR: quic: remove useless quic_tp_dec_err type
+    - MINOR: quic: define QMux transport parameters frame type
+    - MINOR: quic: implement QMux transport params frame parser/builder
+    - MINOR: mux-quic: move qcs stream member into tx inner struct
+    - MINOR: mux-quic: prepare Tx support for QMux
+    - MINOR: mux-quic: convert init/closure for QMux compatibility
+    - MINOR: mux-quic: protect qcc_io_process for QMux
+    - MINOR: mux-quic: prepare traces support for QMux
+    - MINOR: quic: abstract stream type in qf_stream frame
+    - MEDIUM: mux-quic: implement QMux receive
+    - MINOR: mux-quic: handle flow-control frame on qstream read
+    - MINOR: mux-quic: define Rx connection buffer for QMux
+    - MINOR: mux_quic: implement qstrm rx buffer realign
+    - MEDIUM: mux-quic: implement QMux send
+    - MINOR: mux-quic: implement qstream send callback
+    - MINOR: mux-quic: define Tx connection buffer for QMux
+    - MINOR: xprt_qstrm: define new xprt module for QMux protocol
+    - MINOR: xprt_qstrm: define callback for ALPN retrieval
+    - MINOR: xprt_qstrm: implement reception of transport parameters
+    - MINOR: xprt_qstrm: implement sending of transport parameters
+    - MEDIUM: ssl: load xprt_qstrm after handshake completion
+    - MINOR: mux-quic: use QMux transport parameters from qstrm xprt
+    - MAJOR: mux-quic: activate QMux for frontend side
+    - MAJOR: mux-quic: activate QMux on the backend side
+    - MINOR: acme: split the CLI wait from the resolve wait
+    - MEDIUM: acme: initialize the dns timer starting from the first DNS request
+    - DEBUG: connection/flags: add QSTRM flags for the decoder
+    - BUG/MINOR: mux_quic: fix uninit for QMux emission
+    - MINOR: acme: remove remaining CLI wait in ACME_RSLV_TRIGGER
+    - MEDIUM: acme: split the initial delay from the retry DNS delay
+    - BUG/MINOR: cfgcond: properly set the error pointer on evaluation error
+    - BUG/MINOR: cfgcond: always set the error string on openssl_version checks
+    - BUG/MINOR: cfgcond: always set the error string on awslc_api checks
+    - BUG/MINOR: cfgcond: fail cleanly on missing argument for "feature"
+    - MINOR: ssl: add the ssl_fc_crtname sample fetch
+    - MINOR: hasterm: Change hstream_add_data() to prepare zero-copy data forwarding
+    - MEDIUM: haterm: Add support for 0-copy data forwading and option to disable it
+    - MEDIUM: haterm: Prepare support for splicing by initializing a master pipe
+    - MEDIUM: haterm: Add support for splicing and option to disable it
+    - MINOR: haterm: Handle boolean request options as flags
+    - MINOR: haterm: Add an request option to disable splicing
+    - BUG/MINOR: ssl: fix memory leak in ssl_fc_crtname by using SSL_CTX ex_data index
+
 2026/03/20 : 3.4-dev7
     - BUG/MINOR: stconn: Increase SC bytes_out value in se_done_ff()
     - BUG/MINOR: ssl-sample: Fix sample_conv_sha2() by checking EVP_Digest* failures

Makefile

@@ -60,6 +60,7 @@
 #   USE_OBSOLETE_LINKER     : use when the linker fails to emit __start_init/__stop_init
 #   USE_THREAD_DUMP         : use the more advanced thread state dump system. Automatic.
 #   USE_OT                  : enable the OpenTracing filter
+#   USE_OTEL                : enable the OpenTelemetry filter
 #   USE_MEMORY_PROFILING    : enable the memory profiler. Linux-glibc only.
 #   USE_LIBATOMIC           : force to link with/without libatomic. Automatic.
 #   USE_PTHREAD_EMULATION   : replace pthread's rwlocks with ours
@@ -128,6 +129,11 @@
 #   OT_LIB         : force the lib path to libopentracing-c-wrapper
 #   OT_RUNPATH     : add RUNPATH for libopentracing-c-wrapper to haproxy executable
 #   OT_USE_VARS    : allows the use of variables for the OpenTracing context
+#   OTEL_DEBUG     : compile the OpenTelemetry filter in debug mode
+#   OTEL_INC       : force the include path to libopentelemetry-c-wrapper
+#   OTEL_LIB       : force the lib path to libopentelemetry-c-wrapper
+#   OTEL_RUNPATH   : add RUNPATH for libopentelemetry-c-wrapper to haproxy executable
+#   OTEL_USE_VARS  : allows the use of variables for the OpenTelemetry context
 #   IGNOREGIT      : ignore GIT commit versions if set.
 #   VERSION        : force haproxy version reporting.
 #   SUBVERS        : add a sub-version (eg: platform, model, ...).
@@ -347,7 +353,7 @@ use_opts = USE_EPOLL USE_KQUEUE USE_NETFILTER USE_POLL                        \
            USE_CPU_AFFINITY USE_TFO USE_NS USE_DL USE_RT USE_LIBATOMIC        \
            USE_MATH USE_DEVICEATLAS USE_51DEGREES                             \
            USE_WURFL USE_OBSOLETE_LINKER USE_PRCTL USE_PROCCTL                \
-           USE_THREAD_DUMP USE_EVPORTS USE_OT USE_QUIC USE_PROMEX             \
+           USE_THREAD_DUMP USE_EVPORTS USE_OT USE_OTEL USE_QUIC USE_PROMEX    \
            USE_MEMORY_PROFILING USE_SHM_OPEN                                  \
            USE_STATIC_PCRE USE_STATIC_PCRE2                                   \
            USE_PCRE USE_PCRE_JIT USE_PCRE2 USE_PCRE2_JIT                      \
@@ -643,7 +649,7 @@ ifneq ($(USE_OPENSSL:0=),)
   OPTIONS_OBJS += src/ssl_sock.o src/ssl_ckch.o src/ssl_ocsp.o src/ssl_crtlist.o       \
                   src/ssl_sample.o src/cfgparse-ssl.o src/ssl_gencert.o                \
                   src/ssl_utils.o src/jwt.o src/ssl_clienthello.o src/jws.o src/acme.o \
-                  src/ssl_trace.o src/jwe.o
+                  src/acme_resolvers.o src/ssl_trace.o src/jwe.o
 endif
 
 ifneq ($(USE_ENGINE:0=),)
@@ -670,7 +676,7 @@ OPTIONS_OBJS += src/mux_quic.o src/h3.o src/quic_rx.o src/quic_tx.o	\
                 src/quic_cc_nocc.o src/quic_cc.o src/quic_pacing.o	\
                 src/h3_stats.o src/quic_stats.o src/qpack-enc.o		\
                 src/qpack-tbl.o src/quic_cc_drs.o src/quic_fctl.o	\
-                src/quic_enc.o
+                src/quic_enc.o src/mux_quic_qstrm.o src/xprt_qstrm.o
 endif
 
 ifneq ($(USE_QUIC_OPENSSL_COMPAT:0=),)
@@ -862,6 +868,10 @@ ifneq ($(USE_OT:0=),)
   include addons/ot/Makefile
 endif
 
+ifneq ($(USE_OTEL:0=),)
+  include addons/otel/Makefile
+endif
+
 # better keep this one close to the end, as several libs above may need it
 ifneq ($(USE_DL:0=),)
   DL_LDFLAGS = -ldl
@@ -1170,6 +1180,7 @@ clean:
 	$(Q)rm -f addons/51degrees/*.[oas] addons/51degrees/dummy/*.[oas] addons/51degrees/dummy/*/*.[oas]
 	$(Q)rm -f addons/deviceatlas/*.[oas] addons/deviceatlas/dummy/*.[oas] addons/deviceatlas/dummy/*.o
 	$(Q)rm -f addons/deviceatlas/dummy/Os/*.o
+	$(Q)rm -f addons/otel/src/*.[oas]
 	$(Q)rm -f addons/ot/src/*.[oas]
 	$(Q)rm -f addons/wurfl/*.[oas] addons/wurfl/dummy/*.[oas]
 	$(Q)rm -f admin/*/*.[oas] admin/*/*/*.[oas]

VERDATE

@@ -1,2 +1,2 @@
 $Format:%ci$
-2026/03/20
+2026/04/03

VERSION

@@ -1 +1 @@
-3.4-dev7
+3.4-dev8

addons/ot/Makefile

@@ -70,4 +70,4 @@ OPTIONS_OBJS += \
 	addons/ot/src/vars.o
 endif
 
-OT_CFLAGS := $(OT_CFLAGS) -Iaddons/ot/include $(OT_DEFINE)
+OT_CFLAGS := $(OT_CFLAGS) $(OT_DEFINE)

addons/ot/include/debug.h

@@ -35,11 +35,11 @@
 	do {                                                                               \
 		if (!(l) || (flt_ot_debug.level & (1 << (l))))                             \
 			(void)fprintf(stderr, FLT_OT_DBG_FMT("%.*s" f "\n"),               \
-			              dbg_indent_level, FLT_OT_DBG_INDENT, ##__VA_ARGS__); \
+			              flt_ot_dbg_indent_level, FLT_OT_DBG_INDENT, ##__VA_ARGS__); \
 	} while (0)
-#  define FLT_OT_FUNC(f, ...)       do { FLT_OT_DBG(1, "%s(" f ") {", __func__, ##__VA_ARGS__); dbg_indent_level += 3; } while (0)
+#  define FLT_OT_FUNC(f, ...)       do { FLT_OT_DBG(1, "%s(" f ") {", __func__, ##__VA_ARGS__); flt_ot_dbg_indent_level += 3; } while (0)
-#  define FLT_OT_RETURN(a)          do { dbg_indent_level -= 3; FLT_OT_DBG(1, "}"); return a; } while (0)
+#  define FLT_OT_RETURN(a)          do { flt_ot_dbg_indent_level -= 3; FLT_OT_DBG(1, "}"); return a; } while (0)
-#  define FLT_OT_RETURN_EX(a,t,f)   do { dbg_indent_level -= 3; { t _r = (a); FLT_OT_DBG(1, "} = " f, _r); return _r; } } while (0)
+#  define FLT_OT_RETURN_EX(a,t,f)   do { flt_ot_dbg_indent_level -= 3; { t _r = (a); FLT_OT_DBG(1, "} = " f, _r); return _r; } } while (0)
 #  define FLT_OT_RETURN_INT(a)      FLT_OT_RETURN_EX((a), int, "%d")
 #  define FLT_OT_RETURN_PTR(a)      FLT_OT_RETURN_EX((a), void *, "%p")
 #  define FLT_OT_DBG_IFDEF(a,b)     a
@@ -54,7 +54,7 @@ struct flt_ot_debug {
 };
 
 
-extern THREAD_LOCAL int    dbg_indent_level;
+extern THREAD_LOCAL int    flt_ot_dbg_indent_level;
 extern struct flt_ot_debug flt_ot_debug;
 
 #else

addons/ot/src/cli.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 /***

addons/ot/src/conf.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 /***

addons/ot/src/event.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 #define FLT_OT_EVENT_DEF(a,b,c,d,e,f)   { AN_##b##_##a, SMP_OPT_DIR_##b, SMP_VAL_FE_##c, SMP_VAL_BE_##d, e, f },

addons/ot/src/filter.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 /*

addons/ot/src/group.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 #define FLT_OT_GROUP_DEF(a,b,c)   { a, b, c },

addons/ot/src/http.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 #ifdef DEBUG_OT

addons/ot/src/opentracing.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 static struct pool_head *pool_head_ot_span_context __read_mostly = NULL;

addons/ot/src/parser.c

@@ -17,12 +17,12 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 #ifdef DEBUG_OT
 struct flt_ot_debug               flt_ot_debug;
-THREAD_LOCAL int                  dbg_indent_level = 0;
+THREAD_LOCAL int                  flt_ot_dbg_indent_level = 0;
 #endif
 
 #ifdef OTC_DBG_MEM
@@ -359,8 +359,7 @@ static int flt_ot_parse_cfg_sample(const char *file, int linenum, char **args, s
  */
 static int flt_ot_parse_cfg_str(const char *file, int linenum, char **args, struct list *head, char **err)
 {
-	struct flt_ot_conf_str *str = NULL;
+	int i, retval = ERR_NONE;
-	int                     i, retval = ERR_NONE;
 
 	FLT_OT_FUNC("\"%s\", %d, %p, %p, %p:%p", file, linenum, args, head, FLT_OT_DPTR_ARGS(err));
 
@@ -368,9 +367,6 @@ static int flt_ot_parse_cfg_str(const char *file, int linenum, char **args, stru
 		if (flt_ot_conf_str_init(args[i], linenum, head, err) == NULL)
 			retval |= ERR_ABORT | ERR_ALERT;
 
-	if (retval & ERR_CODE)
-		flt_ot_conf_str_free(&str);
-
 	FLT_OT_RETURN_INT(retval);
 }
 
@@ -644,7 +640,7 @@ static int flt_ot_parse_cfg_group(const char *file, int linenum, char **args, in
 
 	if (pdata->keyword == FLT_OT_PARSE_GROUP_ID) {
 		flt_ot_current_group = flt_ot_conf_group_init(args[1], linenum, &(flt_ot_current_config->groups), &err);
-		if (flt_ot_current_config == NULL)
+		if (flt_ot_current_group == NULL)
 			retval |= ERR_ABORT | ERR_ALERT;
 	}
 	else if (pdata->keyword == FLT_OT_PARSE_GROUP_SCOPES) {

addons/ot/src/pool.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 /***

addons/ot/src/scope.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 static struct pool_head *pool_head_ot_scope_span __read_mostly = NULL;

addons/ot/src/util.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 #ifdef DEBUG_OT
@@ -41,7 +41,7 @@ void flt_ot_args_dump(char **args)
 
 	argc = flt_ot_args_count(args);
 
-	(void)fprintf(stderr, FLT_OT_DBG_FMT("%.*sargs[%d]: { '%s' "), dbg_indent_level, FLT_OT_DBG_INDENT, argc, args[0]);
+	(void)fprintf(stderr, FLT_OT_DBG_FMT("%.*sargs[%d]: { '%s' "), flt_ot_dbg_indent_level, FLT_OT_DBG_INDENT, argc, args[0]);
 
 	for (i = 1; i < argc; i++)
 		(void)fprintf(stderr, "'%s' ", args[i]);

addons/ot/src/vars.c

@@ -17,7 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
-#include "include.h"
+#include "../include/include.h"
 
 
 #ifdef DEBUG_OT
@@ -46,10 +46,10 @@ static void flt_ot_vars_scope_dump(struct vars *vars, const char *scope)
 
 	vars_rdlock(vars);
 	for (i = 0; i < VAR_NAME_ROOTS; i++) {
-		struct ceb_node *node = cebu64_first(&(vars->name_root[i]));
+		struct ceb_node *node = cebu64_imm_first(&(vars->name_root[i]));
 
-		for ( ; node != NULL; node = cebu64_next(&(vars->name_root[i]), node)) {
+		for ( ; node != NULL; node = cebu64_imm_next(&(vars->name_root[i]), node)) {
-			struct var *var = container_of(node, struct var, node);
+			struct var *var = container_of(node, struct var, name_node);
 
 			FLT_OT_DBG(2, "'%s.%016" PRIx64 "' -> '%.*s'", scope, var->name_hash, (int)b_data(&(var->data.u.str)), b_orig(&(var->data.u.str)));
 		}

addons/otel/AUTHORS

@@ -0,0 +1 @@
+Miroslav Zagorac <mzagorac@haproxy.com>

addons/otel/MAINTAINERS

@@ -0,0 +1 @@
+Miroslav Zagorac <mzagorac@haproxy.com>

addons/otel/Makefile

@@ -0,0 +1,80 @@
+# USE_OTEL      : enable the OpenTelemetry filter
+# OTEL_DEBUG    : compile the OpenTelemetry filter in debug mode
+# OTEL_INC      : force the include path to libopentelemetry-c-wrapper
+# OTEL_LIB      : force the lib path to libopentelemetry-c-wrapper
+# OTEL_RUNPATH  : add libopentelemetry-c-wrapper RUNPATH to haproxy executable
+# OTEL_USE_VARS : allows the use of variables for the OpenTelemetry context
+
+OTEL_DEFINE    =
+OTEL_CFLAGS    =
+OTEL_LDFLAGS   =
+OTEL_DEBUG_EXT =
+OTEL_PKGSTAT   =
+OTELC_WRAPPER  = opentelemetry-c-wrapper
+
+ifneq ($(OTEL_DEBUG:0=),)
+OTEL_DEBUG_EXT = _dbg
+OTEL_DEFINE    = -DDEBUG_OTEL
+endif
+
+ifeq ($(OTEL_INC),)
+OTEL_PKGSTAT = $(shell pkg-config --exists $(OTELC_WRAPPER)$(OTEL_DEBUG_EXT); echo $$?)
+OTEL_CFLAGS  = $(shell pkg-config --silence-errors --cflags $(OTELC_WRAPPER)$(OTEL_DEBUG_EXT))
+else
+ifneq ($(wildcard $(OTEL_INC)/$(OTELC_WRAPPER)/.*),)
+OTEL_CFLAGS = -I$(OTEL_INC) $(if $(OTEL_DEBUG),-DOTELC_DBG_MEM)
+endif
+endif
+
+ifeq ($(OTEL_PKGSTAT),)
+ifeq ($(OTEL_CFLAGS),)
+$(error OpenTelemetry C wrapper : can't find headers)
+endif
+else
+ifneq ($(OTEL_PKGSTAT),0)
+$(error OpenTelemetry C wrapper : can't find package)
+endif
+endif
+
+ifeq ($(OTEL_LIB),)
+OTEL_LDFLAGS = $(shell pkg-config --silence-errors --libs $(OTELC_WRAPPER)$(OTEL_DEBUG_EXT))
+else
+ifneq ($(wildcard $(OTEL_LIB)/lib$(OTELC_WRAPPER).*),)
+OTEL_LDFLAGS = -L$(OTEL_LIB) -l$(OTELC_WRAPPER)$(OTEL_DEBUG_EXT)
+ifneq ($(OTEL_RUNPATH),)
+OTEL_LDFLAGS += -Wl,--rpath,$(OTEL_LIB)
+endif
+endif
+endif
+
+ifeq ($(OTEL_LDFLAGS),)
+$(error OpenTelemetry C wrapper : can't find library)
+endif
+
+OPTIONS_OBJS += \
+	addons/otel/src/cli.o    \
+	addons/otel/src/conf.o   \
+	addons/otel/src/event.o  \
+	addons/otel/src/filter.o \
+	addons/otel/src/group.o  \
+	addons/otel/src/http.o   \
+	addons/otel/src/otelc.o  \
+	addons/otel/src/parser.o \
+	addons/otel/src/pool.o   \
+	addons/otel/src/scope.o  \
+	addons/otel/src/util.o
+
+ifneq ($(OTEL_USE_VARS:0=),)
+OTEL_DEFINE  += -DUSE_OTEL_VARS
+OPTIONS_OBJS += addons/otel/src/vars.o
+
+# Auto-detect whether struct var has a 'name' member.  When present,
+# prefix-based variable scanning can be used instead of the tracking
+# buffer approach.
+OTEL_VAR_HAS_NAME := $(shell awk '/^struct var \{/,/^\}/' include/haproxy/vars-t.h 2>/dev/null | grep -q '[*]name;' && echo 1)
+ifneq ($(OTEL_VAR_HAS_NAME),)
+OTEL_DEFINE += -DUSE_OTEL_VARS_NAME
+endif
+endif
+
+OTEL_CFLAGS := $(OTEL_CFLAGS) -Iaddons/otel/include $(OTEL_DEFINE)

addons/otel/README-conf

@@ -0,0 +1,456 @@
+OpenTelemetry Filter Configuration Structures
+==============================================================================
+
+1  Overview
+------------------------------------------------------------------------------
+
+The OpenTelemetry filter configuration is a tree of C structures that mirrors
+the hierarchical layout of the filter's configuration file.  Each structure type
+carries a common header macro, and its allocation and deallocation are performed
+by macro-generated init/free function pairs defined in conf_funcs.h.
+
+The root of the tree is flt_otel_conf, which owns the instrumentation settings,
+groups, and scopes.  Scopes contain the actual tracing and metrics definitions:
+contexts, spans, instruments, and their sample expressions.
+
+Source files:
+  include/conf.h        Structure definitions and debug macros.
+  include/conf_funcs.h  Init/free macro templates and declarations.
+  src/conf.c            Init/free implementations for all types.
+
+
+2  Common Macros
+------------------------------------------------------------------------------
+
+Two macros provide the building blocks embedded in every configuration
+structure.
+
+2.1  FLT_OTEL_CONF_STR(p)
+
+Expands to an anonymous struct containing a string pointer and its cached
+length:
+
+  struct {
+      char   *p;
+      size_t  p_len;
+  };
+
+Used for auxiliary string fields that do not need list linkage (e.g. ref_id and
+ctx_id in flt_otel_conf_span).
+
+2.2  FLT_OTEL_CONF_HDR(p)
+
+Expands to an anonymous struct that extends FLT_OTEL_CONF_STR with a
+configuration file line number and an intrusive list node:
+
+  struct {
+      char        *p;
+      size_t       p_len;
+      int          cfg_line;
+      struct list  list;
+  };
+
+Every configuration structure embeds FLT_OTEL_CONF_HDR as its first member.
+The <p> parameter names the identifier field (e.g. "id", "key", "str", "span",
+"fmt_expr").  The list node chains the structure into its parent's list.
+The cfg_line records the source line for error reporting.
+
+
+3  Structure Hierarchy
+------------------------------------------------------------------------------
+
+The complete ownership tree, from root to leaves:
+
+  flt_otel_conf
+  +-- flt_otel_conf_instr                    (one, via pointer)
+  |   +-- flt_otel_conf_ph                   (ph_groups list)
+  |   +-- flt_otel_conf_ph                   (ph_scopes list)
+  |   +-- struct acl                         (acls list, HAProxy-owned type)
+  |   +-- struct logger                      (proxy_log.loggers, HAProxy type)
+  +-- flt_otel_conf_group                    (groups list)
+  |   +-- flt_otel_conf_ph                   (ph_scopes list)
+  +-- flt_otel_conf_scope                    (scopes list)
+      +-- flt_otel_conf_context              (contexts list)
+      +-- flt_otel_conf_span                 (spans list)
+      |   +-- flt_otel_conf_link             (links list)
+      |   +-- flt_otel_conf_sample           (attributes list)
+      |   |   +-- flt_otel_conf_sample_expr  (exprs list)
+      |   +-- flt_otel_conf_sample           (events list)
+      |   |   +-- flt_otel_conf_sample_expr  (exprs list)
+      |   +-- flt_otel_conf_sample           (baggages list)
+      |   |   +-- flt_otel_conf_sample_expr  (exprs list)
+      |   +-- flt_otel_conf_sample           (statuses list)
+      |       +-- flt_otel_conf_sample_expr  (exprs list)
+      +-- flt_otel_conf_str                  (spans_to_finish list)
+      +-- flt_otel_conf_instrument           (instruments list)
+      |   +-- flt_otel_conf_sample           (samples list)
+      |       +-- flt_otel_conf_sample_expr  (exprs list)
+      +-- flt_otel_conf_log_record           (log_records list)
+          +-- flt_otel_conf_sample           (attributes list)
+          |   +-- flt_otel_conf_sample_expr  (exprs list)
+          +-- flt_otel_conf_sample           (samples list)
+              +-- flt_otel_conf_sample_expr  (exprs list)
+
+All child lists use HAProxy's intrusive doubly-linked list (struct list)
+threaded through the FLT_OTEL_CONF_HDR embedded in each child structure.
+
+3.1  Placeholder Structures
+
+The flt_otel_conf_ph structure serves as an indirection node.  During parsing,
+placeholder entries record names of groups and scopes.  At check time
+(flt_otel_check), these names are resolved to pointers to the actual
+flt_otel_conf_group or flt_otel_conf_scope structures via the ptr field.
+Two type aliases exist for clarity:
+
+  #define flt_otel_conf_ph_group  flt_otel_conf_ph
+  #define flt_otel_conf_ph_scope  flt_otel_conf_ph
+
+Corresponding free aliases ensure the FLT_OTEL_LIST_DESTROY macro can locate
+the correct free function:
+
+  #define flt_otel_conf_ph_group_free  flt_otel_conf_ph_free
+  #define flt_otel_conf_ph_scope_free  flt_otel_conf_ph_free
+
+
+4  Structure Definitions
+------------------------------------------------------------------------------
+
+4.1  flt_otel_conf (root)
+
+  proxy      Proxy owning the filter.
+  id         The OpenTelemetry filter id.
+  cfg_file   The OpenTelemetry filter configuration file name.
+  instr      The OpenTelemetry instrumentation settings (pointer).
+  groups     List of all available groups.
+  scopes     List of all available scopes.
+  cnt        Various counters related to filter operation.
+  smp_args   Deferred sample fetch arguments to resolve at check time.
+
+This structure does not use FLT_OTEL_CONF_HDR because it is not part of any
+list -- it is the unique root, owned by the filter instance.
+
+4.2  flt_otel_conf_instr (instrumentation)
+
+  FLT_OTEL_CONF_HDR(id)  The OpenTelemetry instrumentation name.
+  config                 The OpenTelemetry configuration file name.
+  tracer                 The OpenTelemetry tracer handle.
+  meter                  The OpenTelemetry meter handle.
+  logger                 The OpenTelemetry logger handle.
+  rate_limit             Rate limit as uint32 ([0..2^32-1] maps [0..100]%).
+  flag_harderr           Hard-error mode flag.
+  flag_disabled          Disabled flag.
+  logging                Logging mode (0, 1, or 3).
+  proxy_log              The log server list (HAProxy proxy structure).
+  analyzers              Defined channel analyzers bitmask.
+  idle_timeout           Minimum idle timeout across scopes (ms, 0 = off).
+  acls                   ACLs declared on this tracer.
+  ph_groups              List of all used groups (placeholders).
+  ph_scopes              List of all used scopes (placeholders).
+
+Exactly one instrumentation block is allowed per filter instance.  The parser
+stores a pointer to it in flt_otel_conf.instr.
+
+4.3  flt_otel_conf_group
+
+  FLT_OTEL_CONF_HDR(id)  The group name.
+  flag_used              The indication that the group is being used.
+  ph_scopes              List of all used scopes (placeholders).
+
+Groups bundle scopes for use with the "otel-group" HAProxy action.
+
+4.4  flt_otel_conf_scope
+
+  FLT_OTEL_CONF_HDR(id)  The scope name.
+  flag_used              The indication that the scope is being used.
+  event                  FLT_OTEL_EVENT_* identifier.
+  idle_timeout           Idle timeout interval in milliseconds (0 = off).
+  acls                   ACLs declared on this scope.
+  cond                   ACL condition to meet.
+  contexts               Declared contexts.
+  spans                  Declared spans.
+  spans_to_finish        The list of spans scheduled for finishing.
+  instruments            The list of metric instruments.
+  log_records            The list of log records.
+
+Each scope binds to a single HAProxy analyzer event (or none, if used only
+through groups).
+
+4.5  flt_otel_conf_span
+
+  FLT_OTEL_CONF_HDR(id)      The name of the span.
+  FLT_OTEL_CONF_STR(ref_id)  The reference name, if used.
+  FLT_OTEL_CONF_STR(ctx_id)  The span context name, if used.
+  ctx_flags                  The type of storage used for the span context.
+  flag_root                  Whether this is a root span.
+  links                      The set of linked span names.
+  attributes                 The set of key:value attributes.
+  events                     The set of events with key-value attributes.
+  baggages                   The set of key:value baggage items.
+  statuses                   Span status code and description.
+
+The ref_id and ctx_id fields use FLT_OTEL_CONF_STR because they are simple name
+strings without list linkage.
+
+4.6  flt_otel_conf_instrument
+
+  FLT_OTEL_CONF_HDR(id)  The name of the instrument.
+  idx                    Meter instrument index: UNSET (-1) before creation,
+                         PENDING (-2) while another thread is creating, or >= 0
+                         for the actual meter index.
+  type                   Instrument type (or UPDATE).
+  aggr_type              Aggregation type for the view (create only).
+  description            Instrument description (create only).
+  unit                   Instrument unit (create only).
+  samples                Sample expressions for the value.
+  bounds                 Histogram bucket boundaries (create only).
+  bounds_num             Number of histogram bucket boundaries.
+  attributes             Instrument attributes (update only, flt_otel_conf_sample).
+  ref                    Resolved create-form instrument (update only).
+
+Instruments come in two forms: create-form (defines a new metric with type,
+description, unit, and optional histogram bounds) and update-form (references
+an existing instrument via the ref pointer).  Update-form attributes are stored
+as flt_otel_conf_sample entries and evaluated at runtime.
+
+4.7  flt_otel_conf_log_record
+
+  FLT_OTEL_CONF_HDR(id)  Required by macro; member <id> is not used directly.
+  severity               The severity level.
+  event_id               Optional event identifier.
+  event_name             Optional event name.
+  span                   Optional span reference.
+  attributes             Log record attributes (flt_otel_conf_sample list).
+  samples                Sample expressions for the body.
+
+Log records are emitted via the OTel logger at the configured severity.  The
+optional span reference associates the log record with an open span at runtime.
+Attributes are stored as flt_otel_conf_sample entries added via the 'attr'
+keyword, which can be repeated.  Attribute values are HAProxy sample expressions
+evaluated at runtime.
+
+4.8  flt_otel_conf_context
+
+  FLT_OTEL_CONF_HDR(id)  The name of the context.
+  flags                  Storage type from which the span context is extracted.
+
+4.9  flt_otel_conf_sample
+
+  FLT_OTEL_CONF_HDR(key)  The list containing sample names.
+  fmt_string              Combined sample-expression arguments string.
+  extra                   Optional supplementary data.
+  exprs                   Used to chain sample expressions.
+  num_exprs               Number of defined expressions.
+  lf_expr                 The log-format expression.
+  lf_used                 Whether lf_expr is used instead of exprs.
+
+The extra field carries type-specific data: event name strings (OTELC_VALUE_DATA)
+for span events, status code integers (OTELC_VALUE_INT32) for span statuses.
+
+When the sample value argument contains the "%[" sequence, the parser treats
+it as a log-format string: the lf_used flag is set and the compiled result is
+stored in lf_expr, while the exprs list remains empty.  At runtime, if lf_used
+is true, the log-format expression is evaluated via build_logline() instead of
+the sample expression list.
+
+4.10  flt_otel_conf_sample_expr
+
+  FLT_OTEL_CONF_HDR(fmt_expr)  The original expression format string.
+  expr                         The sample expression (struct sample_expr).
+
+4.11  Simple Types
+
+  flt_otel_conf_hdr   Generic header; used for simple named entries.
+  flt_otel_conf_str   String holder (identical to conf_hdr in layout, but the
+                      HDR field is named "str" instead of "id"); used for
+                      spans_to_finish.
+  flt_otel_conf_link  Span link reference; HDR field named "span".
+  flt_otel_conf_ph    Placeholder; carries a ptr field resolved at check time.
+
+
+5  Initialization
+------------------------------------------------------------------------------
+
+5.1  Macro-Generated Init Functions
+
+The FLT_OTEL_CONF_FUNC_INIT macro (conf_funcs.h) generates a function with the
+following signature for each configuration type:
+
+  struct flt_otel_conf_<type> *flt_otel_conf_<type>_init(const char *id, int line, struct list *head, char **err);
+
+The generated function performs these steps:
+
+  1. Validates that <id> is non-NULL and non-empty.
+  2. Checks the identifier length against FLT_OTEL_ID_MAXLEN (64).
+  3. If <head> is non-NULL, iterates the list to reject duplicate identifiers
+     (strcmp match).
+  4. Allocates the structure with OTELC_CALLOC (zeroed memory).
+  5. Records the configuration line number in cfg_line.
+  6. Duplicates the identifier string with OTELC_STRDUP.
+  7. If <head> is non-NULL, appends the structure to the list via LIST_APPEND.
+  8. Executes any custom initialization body provided as the third macro
+     argument.
+
+If any step fails, the function sets an error message via FLT_OTEL_ERR and
+returns NULL.
+
+5.2  Custom Initialization Bodies
+
+Several structure types require additional setup beyond what the macro template
+provides.  The custom init body runs after the base allocation and list
+insertion succeed:
+
+  conf_sample:
+    LIST_INIT for exprs.  Calls lf_expr_init for lf_expr.
+
+  conf_span:
+    LIST_INIT for links, attributes, events, baggages, statuses.
+
+  conf_scope:
+    LIST_INIT for acls, contexts, spans, spans_to_finish, instruments,
+    log_records.
+
+  conf_group:
+    LIST_INIT for ph_scopes.
+
+  conf_instrument:
+    Sets idx and type to OTELC_METRIC_INSTRUMENT_UNSET, aggr_type to
+    OTELC_METRIC_AGGREGATION_UNSET.  LIST_INIT for samples.
+
+  conf_log_record:
+    LIST_INIT for samples.
+
+  conf_instr:
+    Sets rate_limit to FLT_OTEL_FLOAT_U32(100.0) (100%).  Calls init_new_proxy
+    for proxy_log.  LIST_INIT for acls, ph_groups, ph_scopes.
+
+Types with no custom body (hdr, str, link, ph, sample_expr, context) rely
+entirely on the zeroed OTELC_CALLOC allocation.
+
+5.3  Extended Sample Initialization
+
+The flt_otel_conf_sample_init_ex function (conf.c) provides a higher-level
+initialization for sample structures:
+
+  1. Verifies sufficient arguments in the args[] array.
+  2. Calls flt_otel_conf_sample_init with the sample key.
+  3. Copies extra data (event name string or status code integer).
+  4. Concatenates remaining arguments into the fmt_string via
+     flt_otel_args_concat.
+  5. Counts the number of sample expressions.
+
+This function is used by the parser for span attributes, events, baggages,
+statuses, and instrument samples.
+
+5.4  Top-Level Initialization
+
+The flt_otel_conf_init function (conf.c) is hand-written rather than
+macro-generated because the root structure does not follow the standard header
+pattern:
+
+  1. Allocates flt_otel_conf with OTELC_CALLOC.
+  2. Stores the proxy reference.
+  3. Initializes the groups and scopes lists.
+
+
+6  Deallocation
+------------------------------------------------------------------------------
+
+6.1  Macro-Generated Free Functions
+
+The FLT_OTEL_CONF_FUNC_FREE macro (conf_funcs.h) generates a function with the
+following signature:
+
+  void flt_otel_conf_<type>_free(struct flt_otel_conf_<type> **ptr);
+
+The generated function performs these steps:
+
+  1. Checks that both <ptr> and <*ptr> are non-NULL.
+  2. Executes any custom cleanup body provided as the third macro argument.
+  3. Frees the identifier string with OTELC_SFREE.
+  4. Removes the structure from its list with FLT_OTEL_LIST_DEL.
+  5. Frees the structure with OTELC_SFREE_CLEAR and sets <*ptr> to NULL.
+
+6.2  Custom Cleanup Bodies
+
+Custom cleanup runs before the base teardown, allowing child structures to be
+freed while the parent is still valid:
+
+  conf_sample:
+    Frees fmt_string.  If extra is OTELC_VALUE_DATA, frees the data pointer.
+    Destroys the exprs list (sample_expr entries).  Deinitializes lf_expr via
+    lf_expr_deinit.
+
+  conf_sample_expr:
+    Releases the HAProxy sample expression via release_sample_expr.
+
+  conf_span:
+    Frees ref_id and ctx_id strings.
+    Destroys links, attributes, events, baggages, and statuses lists.
+
+  conf_instrument:
+    Frees description, unit, and bounds.  Destroys the samples list.
+    Destroys the attr key-value array via otelc_kv_destroy.
+
+  conf_log_record:
+    Frees event_name and span strings.  Destroys the attr key-value array via
+    otelc_kv_destroy.  Destroys the samples list.
+
+  conf_scope:
+    Prunes and frees each ACL entry.  Frees the ACL condition via free_acl_cond.
+    Destroys contexts, spans, spans_to_finish, instruments, and log_records
+    lists.
+
+  conf_group:
+    Destroys the ph_scopes list.
+
+  conf_instr:
+    Frees the config string.  Prunes and frees each ACL entry.  Frees each
+    logger entry from proxy_log.loggers.  Destroys the ph_groups and ph_scopes
+    lists.
+
+Types with no custom cleanup (hdr, str, link, ph, context) only run the base
+teardown: free the identifier, unlink, free the structure.
+
+6.3  List Destruction
+
+The FLT_OTEL_LIST_DESTROY(type, head) macro (defined in define.h) iterates a
+list and calls flt_otel_conf_<type>_free for each entry.  This macro drives the
+recursive teardown from parent to leaf.
+
+6.4  Top-Level Deallocation
+
+The flt_otel_conf_free function (conf.c) is hand-written:
+
+  1. Frees the id and cfg_file strings.
+  2. Calls flt_otel_conf_instr_free for the instrumentation.
+  3. Destroys the groups list (which recursively frees placeholders).
+  4. Destroys the scopes list (which recursively frees contexts, spans,
+     instruments, log records, and all their children).
+  5. Frees the root structure and sets the pointer to NULL.
+
+
+7  Summary of Init/Free Pairs
+------------------------------------------------------------------------------
+
+The following table lists all configuration types and their init/free function
+pairs.  Types marked "macro" are generated by the FLT_OTEL_CONF_FUNC_(INIT|FREE)
+macros.  The HDR field column shows which member name is used for the common
+header.
+
+  Type             HDR field  Source  Custom init body
+  ---------------  ---------  ------  -------------------------
+  conf             (none)     manual  groups, scopes
+  conf_hdr         id         macro   (none)
+  conf_str         str        macro   (none)
+  conf_link        span       macro   (none)
+  conf_ph          id         macro   (none)
+  conf_sample_expr fmt_expr   macro   (none)
+  conf_sample      key        macro   exprs, lf_expr
+  conf_sample (ex) key        manual  extra, fmt_string, exprs
+  conf_context     id         macro   (none)
+  conf_span        id         macro   5 sub-lists
+  conf_instrument  id         macro   idx, type, samples
+  conf_log_record  id         macro   samples
+  conf_scope       id         macro   6 sub-lists
+  conf_group       id         macro   ph_scopes
+  conf_instr       id         macro   rate_limit, proxy_log, acls, ph_groups, ph_scopes

addons/otel/README-configuration

@@ -0,0 +1,951 @@
+                   -----------------------------------------
+                    HAProxy OTel filter configuration guide
+                                Version 1.0
+                        ( Last update: 2026-03-18 )
+                   -----------------------------------------
+                         Author : Miroslav Zagorac
+                   Contact : mzagorac at haproxy dot com
+
+
+SUMMARY
+--------
+
+  1.    Overview
+  2.    HAProxy filter declaration
+  3.    OTel configuration file structure
+  3.1.    OTel scope (top-level)
+  3.2.    "otel-instrumentation" section
+  3.3.    "otel-scope" section
+  3.4.    "otel-group" section
+  4.    YAML configuration file
+  4.1.    Exporters
+  4.2.    Samplers
+  4.3.    Processors
+  4.4.    Readers
+  4.5.    Providers
+  4.6.    Signals
+  5.    HAProxy rule integration
+  6.    Complete examples
+  6.1.    Standalone example (sa)
+  6.2.    Frontend / backend example (fe/be)
+  6.3.    Context propagation example (ctx)
+  6.4.    Comparison example (cmp)
+  6.5.    Empty / minimal example (empty)
+
+
+1. Overview
+------------
+
+The OTel filter configuration consists of two files:
+
+  1) An OTel configuration file (.cfg) that defines the tracing model: scopes,
+     groups, spans, attributes, events, instrumentation and log-records.
+
+  2) A YAML configuration file (.yml) that configures the OpenTelemetry SDK
+     pipeline: exporters, samplers, processors, readers, providers and signal
+     routing.
+
+The OTel configuration file is referenced from the HAProxy configuration using
+the 'filter opentelemetry' directive.  The YAML file is in turn referenced from
+the OTel configuration file using the 'config' keyword inside the
+"otel-instrumentation" section.
+
+
+2. HAProxy filter declaration
+------------------------------
+
+The OTel filter requires the 'insecure-fork-wanted' keyword in the HAProxy
+'global' section.  This is necessary because the OpenTelemetry C++ SDK creates
+background threads for data export and batch processing.  HAProxy will refuse
+to load the configuration if this keyword is missing.
+
+  global
+      insecure-fork-wanted
+      ...
+
+The filter is activated by adding a filter directive in the HAProxy
+configuration, in a proxy section (frontend / listen / backend):
+
+  frontend my-frontend
+    ...
+    filter opentelemetry [id <id>] config <otel-cfg-file>
+    ...
+
+If no filter id is specified, 'otel-filter' is used as default.  The 'config'
+parameter is mandatory and specifies the path to the OTel configuration file.
+
+Example (from test/sa/haproxy.cfg):
+
+  frontend otel-test-sa-frontend
+      bind *:10080
+      default_backend servers-backend
+
+      acl acl-http-status-ok status 100:399
+
+      filter opentelemetry id otel-test-sa config sa/otel.cfg
+
+      http-response otel-group otel-test-sa http_response_group if acl-http-status-ok
+      http-after-response otel-group otel-test-sa http_after_response_group if !acl-http-status-ok
+
+  backend servers-backend
+      server server-1 127.0.0.1:8000
+
+
+3. OTel configuration file structure
+--------------------------------------
+
+The OTel configuration file uses a simple section-based format.  It contains
+three types of sections: one "otel-instrumentation" section (mandatory), zero
+or more "otel-scope" sections, and zero or more "otel-group" sections.
+
+
+3.1. OTel scope (top-level)
+-----------------------------
+
+The file is organized into top-level OTel scopes, each identified by a filter
+id enclosed in square brackets.  The filter id must match the id specified in
+the HAProxy 'filter opentelemetry' directive.
+
+  [<filter-id>]
+      otel-instrumentation <name>
+          ...
+
+      otel-group <name>
+          ...
+
+      otel-scope <name>
+          ...
+
+Multiple OTel scopes (for different filter instances) can coexist in the same
+file:
+
+  [my-first-filter]
+      otel-instrumentation instr1
+          ...
+
+  [my-second-filter]
+      otel-instrumentation instr2
+          ...
+
+
+3.2. "otel-instrumentation" section
+-------------------------------------
+
+Exactly one "otel-instrumentation" section must be defined per OTel scope.
+It configures the global behavior of the filter and declares which groups
+and scopes are active.
+
+Syntax:
+
+  otel-instrumentation <name>
+
+Keywords (mandatory):
+
+  config <file>
+      Path to the YAML configuration file for the OpenTelemetry SDK.
+
+Keywords (optional):
+
+  acl <aclname> <criterion> [flags] [operator] <value> ...
+      Declare an ACL.  See section 7 of the HAProxy Configuration Manual.
+
+  debug-level <value>
+      Set the debug level bitmask (e.g. 0x77f).  Only effective when compiled
+      with OTEL_DEBUG=1.
+
+  groups <name> ...
+      Declare one or more "otel-group" sections used by this instrumentation.
+      Can be repeated on multiple lines.
+
+  log global
+  log <addr> [len <len>] [format <fmt>] <facility> [<level> [<minlvl>]]
+  no log
+      Enable per-instance logging.
+
+  option disabled / no option disabled
+      Disable or enable the filter.  Default: enabled.
+
+  option dontlog-normal / no option dontlog-normal
+      Suppress logging for normal (successful) operations.  Default: disabled.
+
+  option hard-errors / no option hard-errors
+      Stop all filter processing in a stream after the first error.  Default:
+      disabled (errors are non-fatal).
+
+  rate-limit <value>
+      Percentage of streams for which the filter is activated.  Floating-point
+      value from 0.0 to 100.0.  Default: 100.0.
+
+  scopes <name> ...
+      Declare one or more "otel-scope" sections used by this instrumentation.
+      Can be repeated on multiple lines.
+
+
+Example (from test/sa/otel.cfg):
+
+  [otel-test-sa]
+      otel-instrumentation otel-test-instrumentation
+          debug-level 0x77f
+          log localhost:514 local7 debug
+          config sa/otel.yml
+          option dontlog-normal
+          option hard-errors
+          no option disabled
+          rate-limit 100.0
+
+          groups http_response_group
+          groups http_after_response_group
+
+          scopes on_stream_start
+          scopes on_stream_stop
+
+          scopes client_session_start
+          scopes frontend_tcp_request
+          ...
+          scopes server_session_end
+
+
+3.3. "otel-scope" section
+---------------------------
+
+An "otel-scope" section defines the actions that take place when a particular
+event fires or when a group is triggered.
+
+Syntax:
+
+  otel-scope <name>
+
+Supported keywords:
+
+  span <name> [parent <ref>] [link <ref>] [root]
+      Create a new span or reference an already opened one.
+
+      - 'root' marks this span as the trace root (only one per trace).
+      - 'parent <ref>' sets the parent to an existing span or extracted context
+        name.
+      - 'link <ref>' adds an inline link to another span or context.  Multiple
+        inline links can be specified within the argument limit.
+      - If no reference is given, the span becomes a root span.
+
+      A span declaration opens a "sub-context" within the scope: the keywords
+      'link', 'attribute', 'event', 'baggage', 'status' and 'inject' that follow
+      apply to that span until the next 'span' keyword or the end of the scope.
+
+      Examples:
+        span "HAProxy session" root
+        span "Client session" parent "HAProxy session"
+        span "HTTP request" parent "TCP request" link "HAProxy session"
+        span "Client session" parent "otel_ctx_1"
+
+
+  attribute <key> <sample> ...
+      Set an attribute on the currently active span.  A single sample preserves
+      its native type; multiple samples are concatenated as a string.
+
+      Examples:
+        attribute "http.method" method
+        attribute "http.url" url
+        attribute "http.version" str("HTTP/") req.ver
+
+
+  event <name> <key> <sample> ...
+      Add a span event (timestamped annotation) to the currently active span.
+      The data type is always string.
+
+      Examples:
+        event "event_ip" "src" src str(":") src_port
+        event "event_be" "be" be_id str(" ") be_name
+
+
+  baggage <key> <sample> ...
+      Set baggage on the currently active span.  Baggage propagates to all child
+      spans.  The data type is always string.
+
+      Example:
+        baggage "haproxy_id" var(sess.otel.uuid)
+
+
+  status <code> [<sample> ...]
+      Set the span status.  Valid codes: ignore (default), unset, ok, error.
+      An optional description follows the code.
+
+      Examples:
+        status "ok"
+        status "error" str("http.status_code: ") status
+
+
+  link <span> ...
+      Add non-hierarchical links to the currently active span.  Multiple span
+      names can be specified.  Use this keyword for multiple links (the inline
+      'link' in 'span' is limited to one).
+
+      Example:
+        link "HAProxy session" "Client session"
+
+
+  inject <name-prefix> [use-vars] [use-headers]
+      Inject span context into an HTTP header carrier and/or HAProxy variables.
+      The prefix names the context; the special prefix '-' generates the name
+      automatically.  Default storage: use-headers.  The 'use-vars' option
+      requires OTEL_USE_VARS=1 at compile time.
+
+      Example:
+        span "HAProxy session" root
+            inject "otel_ctx_1" use-headers use-vars
+
+
+  extract <name-prefix> [use-vars | use-headers]
+      Extract a previously injected span context from an HTTP header or HAProxy
+      variables.  The extracted context can then be used as a parent reference
+      in 'span ... parent <name-prefix>'.
+
+      Example:
+        extract "otel_ctx_1" use-vars
+        span "Client session" parent "otel_ctx_1"
+
+
+  finish <name> ...
+      Close one or more spans or span contexts.  Special names:
+        '*'      - finish all open spans
+        '*req*'  - finish all request-channel spans
+        '*res*'  - finish all response-channel spans
+
+      Multiple names can be given on one line.  A quoted context name after a
+      span name finishes the associated context as well.
+
+      Examples:
+        finish "Frontend TCP request"
+        finish "Client session" "otel_ctx_2"
+        finish *
+
+
+  instrument <type> <name> [aggr <aggregation>] [desc <description>] [unit <unit>] value <sample> [bounds <bounds>]
+  instrument update <name> [attr <key> <sample> ...]
+      Create or update a metric instrument.
+
+      Supported types:
+        cnt_int   - counter (uint64)
+        hist_int  - histogram (uint64)
+        udcnt_int - up-down counter (int64)
+        gauge_int - gauge (int64)
+
+      Supported aggregation types:
+        drop           - measurements are discarded
+        histogram      - explicit bucket histogram
+        last_value     - last recorded value
+        sum            - sum of recorded values
+        default        - SDK default for the instrument type
+        exp_histogram  - base-2 exponential histogram
+
+      An aggregation type can be specified using the 'aggr' keyword.  When
+      specified, a metrics view is registered with the given aggregation
+      strategy.  If omitted, the SDK default is used.
+
+      For histogram instruments (hist_int), optional bucket boundaries can be
+      specified using the 'bounds' keyword followed by a double-quoted string
+      of space-separated numbers (order does not matter; values are sorted
+      internally).  When bounds are specified without an explicit aggregation
+      type, histogram aggregation is used automatically.
+
+      Observable (asynchronous) and double-precision types are not supported.
+      Observable instrument callbacks are invoked by the OTel SDK from an
+      external background thread; HAProxy sample fetches rely on internal
+      per-thread-group state and return incorrect results from a non-HAProxy
+      thread.  Double-precision types are not supported because HAProxy sample
+      fetches do not return double values.
+
+      Examples:
+        instrument cnt_int  "name_cnt_int" desc "Integer Counter" value int(1),add(2) unit "unit"
+        instrument hist_int "name_hist" aggr exp_histogram desc "Latency" value lat_ns_tot unit "ns"
+        instrument hist_int "name_hist2" desc "Latency" value lat_ns_tot unit "ns" bounds "100 1000 10000"
+        instrument update "name_cnt_int" attr "attr_1_key" str("attr_1_value")
+
+
+  log-record <severity> [id <integer>] [event <name>] [span <span-name>] [attr <key> <sample>] ... <sample> ...
+      Emit an OpenTelemetry log record.  The first argument is a required
+      severity level.  Optional keywords follow in any order:
+
+        id <integer>        - numeric event identifier
+        event <name>        - event name string
+        span <span-name>    - associate the log record with an open span
+        attr <key> <sample> - add an attribute evaluated at runtime (repeatable)
+
+      The 'attr' keyword takes an attribute name and a single HAProxy sample
+      expression.  The expression is evaluated at runtime, following the same
+      rules as span attributes: a bare sample fetch (e.g. src) or a log-format
+      string (e.g. "%[src]:%[src_port]").
+
+      The remaining arguments at the end are sample fetch expressions that form
+      the log record body.  A single sample preserves its native type; multiple
+      samples are concatenated as a string.
+
+      Supported severity levels follow the OpenTelemetry specification:
+        trace, trace2, trace3, trace4
+        debug, debug2, debug3, debug4
+        info,  info2,  info3,  info4
+        warn,  warn2,  warn3,  warn4
+        error, error2, error3, error4
+        fatal, fatal2, fatal3, fatal4
+
+      The log record is only emitted if the logger is enabled for the configured
+      severity (controlled by the 'min_severity' option in the YAML logs signal
+      configuration).  If a 'span' reference is given but the named span is not
+      found at runtime, the log record is emitted without span correlation.
+
+      Examples:
+        log-record info str("heartbeat")
+        log-record info id 1001 event "http-request" span "Frontend HTTP request" attr "http.method" method method url
+        log-record trace id 1000 event "session-start" span "Client session" attr "src_ip" src attr "src_port" src_port src str(":") src_port
+        log-record warn event "server-unavailable" str("503 Service Unavailable")
+        log-record info event "session-stop" str("stream stopped")
+
+
+  acl <aclname> <criterion> [flags] [operator] <value> ...
+      Declare an ACL local to this scope.
+
+      Example:
+        acl acl-test-src-ip src 127.0.0.1
+
+
+  otel-event <name> [{ if | unless } <condition>]
+      Bind this scope to a filter event, optionally with an ACL-based condition.
+
+      Supported events (stream lifecycle):
+        on-stream-start
+        on-stream-stop
+        on-idle-timeout
+        on-backend-set
+
+      Supported events (request channel):
+        on-client-session-start
+        on-frontend-tcp-request
+        on-http-wait-request
+        on-http-body-request
+        on-frontend-http-request
+        on-switching-rules-request
+        on-backend-tcp-request
+        on-backend-http-request
+        on-process-server-rules-request
+        on-http-process-request
+        on-tcp-rdp-cookie-request
+        on-process-sticking-rules-request
+        on-http-headers-request
+        on-http-end-request
+        on-client-session-end
+        on-server-unavailable
+
+      Supported events (response channel):
+        on-server-session-start
+        on-tcp-response
+        on-http-wait-response
+        on-process-store-rules-response
+        on-http-response
+        on-http-headers-response
+        on-http-end-response
+        on-http-reply
+        on-server-session-end
+
+      The on-stream-start event fires from the stream_start filter callback,
+      before any channel processing begins.  The on-stream-stop event fires from
+      the stream_stop callback, after all channel processing ends.  No channel
+      is available at that point, so context injection/extraction via HTTP
+      headers cannot be used in scopes bound to these events.
+
+      The on-idle-timeout event fires periodically when the stream has no data
+      transfer activity.  It requires the 'idle-timeout' keyword to set the
+      interval.  Scopes bound to this event can create heartbeat spans, record
+      idle-time metrics, and emit idle-time log records.
+
+      The on-backend-set event fires when a backend is assigned to the stream.
+      It is not called if the frontend and backend are the same.
+
+      The on-http-headers-request and on-http-headers-response events fire after
+      all HTTP headers have been parsed and analyzed.
+
+      The on-http-end-request and on-http-end-response events fire when all HTTP
+      data has been processed and forwarded.
+
+      The on-http-reply event fires when HAProxy generates an internal reply
+      (error page, deny response, redirect).
+
+      Examples:
+        otel-event on-stream-start if acl-test-src-ip
+        otel-event on-stream-stop
+        otel-event on-client-session-start
+        otel-event on-client-session-start if acl-test-src-ip
+        otel-event on-http-response if !acl-http-status-ok
+        otel-event on-idle-timeout
+
+
+  idle-timeout <time>
+      Set the idle timeout interval for a scope bound to the 'on-idle-timeout'
+      event.  The timer fires periodically at the given interval when the stream
+      has no data transfer activity.  This keyword is mandatory for scopes using
+      the 'on-idle-timeout' event and cannot be used with any other event.
+
+      The <time> argument accepts the standard HAProxy time format: a number
+      followed by a unit suffix (ms, s, m, h, d).  A value of zero is not
+      permitted.
+
+      Example:
+        scopes on_idle_timeout
+        ..
+        otel-scope on_idle_timeout
+            idle-timeout 5s
+            span "heartbeat" root
+                attribute "idle.elapsed" str("idle-check")
+            instrument cnt_int "idle.count" value int(1)
+            log-record info str("heartbeat")
+            otel-event on-idle-timeout
+
+
+3.4. "otel-group" section
+---------------------------
+
+An "otel-group" section defines a named collection of scopes that can be
+triggered from HAProxy TCP/HTTP rules rather than from filter events.
+
+Syntax:
+
+  otel-group <name>
+
+Keywords:
+
+  scopes <name> ...
+      List the "otel-scope" sections that belong to this group.  Multiple names
+      can be given on one line.  Scopes that are used only in groups do not need
+      to define an 'otel-event'.
+
+Example (from test/sa/otel.cfg):
+
+  otel-group http_response_group
+      scopes http_response_1
+      scopes http_response_2
+
+  otel-scope http_response_1
+      span "HTTP response"
+          event "event_content" "hdr.content" res.hdr("content-type") str("; length: ") res.hdr("content-length") str(" bytes")
+
+  otel-scope http_response_2
+      span "HTTP response"
+          event "event_date" "hdr.date" res.hdr("date") str(" / ") res.hdr("last-modified")
+
+
+4. YAML configuration file
+----------------------------
+
+The YAML configuration file defines the OpenTelemetry SDK pipeline.  It is
+referenced by the 'config' keyword in the "otel-instrumentation" section.
+It contains the following top-level sections: exporters, samplers, processors,
+readers, providers and signals.
+
+
+4.1. Exporters
+---------------
+
+Each exporter has a user-chosen name and a 'type' that determines which
+additional options are available.  Options marked with (*) are required.
+
+Supported types:
+
+  otlp_grpc - Export via OTLP over gRPC.
+    type (*)                          "otlp_grpc"
+    thread_name                       exporter thread name (string)
+    endpoint                          OTLP/gRPC endpoint URL (string)
+    use_ssl_credentials               enable SSL channel credentials (boolean)
+    ssl_credentials_cacert_path       CA certificate file path (string)
+    ssl_credentials_cacert_as_string  CA certificate as inline string (string)
+    ssl_client_key_path               client private key file path (string)
+    ssl_client_key_string             client private key as inline string (string)
+    ssl_client_cert_path              client certificate file path (string)
+    ssl_client_cert_string            client certificate as inline string (string)
+    timeout                           export timeout in seconds (integer)
+    user_agent                        User-Agent header value (string)
+    max_threads                       maximum exporter threads (integer)
+    compression                       compression algorithm name (string)
+    max_concurrent_requests           concurrent request limit (integer)
+
+
+  otlp_http - Export via OTLP over HTTP (JSON or Protobuf).
+    type (*)                        "otlp_http"
+    thread_name                     exporter thread name (string)
+    endpoint                        OTLP/HTTP endpoint URL (string)
+    content_type                    payload format: "json" or "protobuf"
+    json_bytes_mapping              binary encoding: "hexid", "utf8" or "base64"
+    debug                           enable debug output (boolean)
+    timeout                         export timeout in seconds (integer)
+    http_headers                    custom HTTP headers (list of key: value)
+    max_concurrent_requests         concurrent request limit (integer)
+    max_requests_per_connection     request limit per connection (integer)
+    ssl_insecure_skip_verify        skip TLS certificate verification (boolean)
+    ssl_ca_cert_path                CA certificate file path (string)
+    ssl_ca_cert_string              CA certificate as inline string (string)
+    ssl_client_key_path             client private key file path (string)
+    ssl_client_key_string           client private key as inline string (string)
+    ssl_client_cert_path            client certificate file path (string)
+    ssl_client_cert_string          client certificate as inline string (string)
+    ssl_min_tls                     minimum TLS version (string)
+    ssl_max_tls                     maximum TLS version (string)
+    ssl_cipher                      TLS cipher list (string)
+    ssl_cipher_suite                TLS 1.3 cipher suite list (string)
+    compression                     compression algorithm name (string)
+
+
+  otlp_file - Export to local files in OTLP format.
+    type (*)                        "otlp_file"
+    thread_name                     exporter thread name (string)
+    file_pattern                    output filename pattern (string)
+    alias_pattern                   symlink pattern for latest file (string)
+    flush_interval                  flush interval in microseconds (integer)
+    flush_count                     spans per flush (integer)
+    file_size                       maximum file size in bytes (integer)
+    rotate_size                     number of rotated files to keep (integer)
+
+
+  ostream - Write to a file (text output, useful for debugging).
+    type (*)                        "ostream"
+    filename                        output file path (string)
+
+
+  memory - In-memory buffer (useful for testing).
+    type (*)                        "memory"
+    buffer_size                     maximum buffered items (integer)
+
+
+  zipkin - Export to Zipkin-compatible backends.
+    type (*)                        "zipkin"
+    endpoint                        Zipkin collector URL (string)
+    format                          payload format: "json" or "protobuf"
+    service_name                    service name reported to Zipkin (string)
+    ipv4                            service IPv4 address (string)
+    ipv6                            service IPv6 address (string)
+
+
+  elasticsearch - Export to Elasticsearch.
+    type (*)                        "elasticsearch"
+    host                            Elasticsearch hostname (string)
+    port                            Elasticsearch port (integer)
+    index                           Elasticsearch index name (string)
+    response_timeout                response timeout in seconds (integer)
+    debug                           enable debug output (boolean)
+    http_headers                    custom HTTP headers (list of key: value)
+
+
+4.2. Samplers
+--------------
+
+Samplers control which traces are recorded.  Each sampler has a user-chosen
+name and a 'type' that determines its behavior.
+
+Supported types:
+
+  always_on - Sample every trace.
+    type (*)                        "always_on"
+
+
+  always_off - Sample no traces.
+    type (*)                        "always_off"
+
+
+  trace_id_ratio_based - Sample a fraction of traces.
+    type (*)                        "trace_id_ratio_based"
+    ratio                           sampling ratio, 0.0 to 1.0 (float)
+
+
+  parent_based - Inherit sampling decision from parent span.
+    type (*)                        "parent_based"
+    delegate                        fallback sampler name (string)
+
+
+4.3. Processors
+----------------
+
+Processors define how telemetry data is handled before export.  Each
+processor has a user-chosen name and a 'type' that determines its behavior.
+
+Supported types:
+
+  batch - Batch spans before exporting.
+    type (*)                        "batch"
+    thread_name                     processor thread name (string)
+    max_queue_size                  maximum queued spans (integer)
+    schedule_delay                  export interval in milliseconds (integer)
+    max_export_batch_size           maximum spans per export call (integer)
+
+    When the queue reaches half capacity, a preemptive notification triggers
+    an early export.
+
+  single - Export each span individually (no batching).
+    type (*)                        "single"
+
+
+4.4. Readers
+-------------
+
+Readers define how metrics are collected and exported.  Each reader has a
+user-chosen name.
+
+    thread_name                     reader thread name (string)
+    export_interval                 collection interval in milliseconds (integer)
+    export_timeout                  export timeout in milliseconds (integer)
+
+
+4.5. Providers
+---------------
+
+Providers define resource attributes attached to all telemetry data.  Each
+provider has a user-chosen name.
+
+    resources                       key-value resource attributes (list)
+
+Standard resource attribute keys include service.name, service.version,
+service.instance.id and service.namespace.
+
+
+4.6. Signals
+-------------
+
+Signals bind exporters, samplers, processors, readers and providers together
+for each telemetry type.  The supported signal names are "traces", "metrics"
+and "logs".
+
+    scope_name                      instrumentation scope name (string)
+    exporters                       exporter name reference (string)
+    samplers                        sampler name reference (string, traces only)
+    processors                      processor name reference (string, traces/logs)
+    readers                         reader name reference (string, metrics only)
+    providers                       provider name reference (string)
+    min_severity                    minimum log severity level (string, logs only)
+
+The "min_severity" option controls which log records are emitted.  Only log
+records whose severity is equal to or higher than the configured minimum are
+passed to the exporter.  The value is a severity name as listed under the
+"log-record" keyword (e.g. "trace", "debug", "info", "warn", "error", "fatal").
+If omitted, the logger accepts all severity levels.
+
+
+5. HAProxy rule integration
+----------------------------
+
+Groups defined in the OTel configuration file can be triggered from HAProxy
+TCP/HTTP rules using the 'otel-group' action keyword:
+
+  http-request        otel-group <filter-id> <group> [condition]
+  http-response       otel-group <filter-id> <group> [condition]
+  http-after-response otel-group <filter-id> <group> [condition]
+  tcp-request         otel-group <filter-id> <group> [condition]
+  tcp-response        otel-group <filter-id> <group> [condition]
+
+This allows running specific groups of scopes based on ACL conditions defined
+in the HAProxy configuration.
+
+Example (from test/sa/haproxy.cfg):
+
+  acl acl-http-status-ok status 100:399
+
+  filter opentelemetry id otel-test-sa config sa/otel.cfg
+
+  # Run response scopes for successful responses
+  http-response otel-group otel-test-sa http_response_group if acl-http-status-ok
+
+  # Run after-response scopes for error responses
+  http-after-response otel-group otel-test-sa http_after_response_group if !acl-http-status-ok
+
+
+6. Complete examples
+---------------------
+
+The test directory contains several complete example configurations.  Each
+subdirectory contains an OTel configuration file (otel.cfg), a YAML file
+(otel.yml) and a HAProxy configuration file (haproxy.cfg).
+
+
+6.1. Standalone example (sa)
+------------------------------
+
+The most comprehensive example.  All possible events are used, with spans,
+attributes, events, links, baggage, status, metrics and groups demonstrated.
+
+--- test/sa/otel.cfg (excerpt) -----------------------------------------
+
+[otel-test-sa]
+    otel-instrumentation otel-test-instrumentation
+        config sa/otel.yml
+        option dontlog-normal
+        option hard-errors
+        no option disabled
+        rate-limit 100.0
+
+        groups http_response_group
+        groups http_after_response_group
+
+        scopes on_stream_start
+        scopes on_stream_stop
+        scopes client_session_start
+        scopes frontend_tcp_request
+        ...
+        scopes server_session_end
+
+    otel-group http_response_group
+        scopes http_response_1
+        scopes http_response_2
+
+    otel-scope http_response_1
+        span "HTTP response"
+            event "event_content" "hdr.content" res.hdr("content-type") str("; length: ") res.hdr("content-length") str(" bytes")
+
+    otel-scope on_stream_start
+        instrument udcnt_int "haproxy.sessions.active" desc "Active sessions" value int(1) unit "{session}"
+        span "HAProxy session" root
+            baggage "haproxy_id" var(sess.otel.uuid)
+            event "event_ip" "src" src str(":") src_port
+        acl acl-test-src-ip src 127.0.0.1
+        otel-event on-stream-start if acl-test-src-ip
+
+    otel-scope on_stream_stop
+        finish *
+        otel-event on-stream-stop
+
+    otel-scope client_session_start
+        span "Client session" parent "HAProxy session"
+        otel-event on-client-session-start
+
+    otel-scope frontend_http_request
+        span "Frontend HTTP request" parent "HTTP body request" link "HAProxy session"
+            attribute "http.method" method
+            attribute "http.url" url
+            attribute "http.version" str("HTTP/") req.ver
+        finish "HTTP body request"
+        otel-event on-frontend-http-request
+
+    otel-scope server_session_start
+        span "Server session" parent "HAProxy session"
+        link "HAProxy session" "Client session"
+        finish "Process sticking rules request"
+        otel-event on-server-session-start
+
+    otel-scope server_session_end
+        finish *
+        otel-event on-server-session-end
+
+---------------------------------------------------------------------
+
+
+6.2. Frontend / backend example (fe/be)
+-----------------------------------------
+
+Demonstrates distributed tracing across two cascaded HAProxy instances using
+inject/extract to propagate the span context via HTTP headers.
+
+The frontend HAProxy (test/fe) creates the root trace and injects context:
+
+--- test/fe/otel.cfg (excerpt) -----------------------------------------
+
+    otel-scope backend_http_request
+        span "Backend HTTP request" parent "Backend TCP request"
+        finish "Backend TCP request"
+        span "HAProxy session"
+            inject "otel-ctx" use-headers
+        otel-event on-backend-http-request
+
+---------------------------------------------------------------------
+
+The backend HAProxy (test/be) extracts the context and continues the trace:
+
+--- test/be/otel.cfg (excerpt) -----------------------------------------
+
+    otel-scope frontend_http_request
+        extract "otel-ctx" use-headers
+        span "HAProxy session" parent "otel-ctx" root
+            baggage "haproxy_id" var(sess.otel.uuid)
+        span "Client session" parent "HAProxy session"
+        span "Frontend HTTP request" parent "Client session"
+            attribute "http.method" method
+            attribute "http.url" url
+            attribute "http.version" str("HTTP/") req.ver
+        otel-event on-frontend-http-request
+
+---------------------------------------------------------------------
+
+
+6.3. Context propagation example (ctx)
+----------------------------------------
+
+Similar to 'sa', but spans are opened using extracted span contexts as parent
+references instead of direct span names.  This demonstrates the inject/extract
+mechanism using HAProxy variables.
+
+--- test/ctx/otel.cfg (excerpt) ----------------------------------------
+
+    otel-scope client_session_start_1
+        span "HAProxy session" root
+            inject "otel_ctx_1" use-headers use-vars
+            baggage "haproxy_id" var(sess.otel.uuid)
+        otel-event on-client-session-start
+
+    otel-scope client_session_start_2
+        extract "otel_ctx_1" use-vars
+        span "Client session" parent "otel_ctx_1"
+            inject "otel_ctx_2" use-headers use-vars
+        otel-event on-client-session-start
+
+    otel-scope frontend_tcp_request
+        extract "otel_ctx_2" use-vars
+        span "Frontend TCP request" parent "otel_ctx_2"
+            inject "otel_ctx_3" use-headers use-vars
+        otel-event on-frontend-tcp-request
+
+    otel-scope http_wait_request
+        extract "otel_ctx_3" use-vars
+        span "HTTP wait request" parent "otel_ctx_3"
+        finish "Frontend TCP request" "otel_ctx_3"
+        otel-event on-http-wait-request
+
+---------------------------------------------------------------------
+
+
+6.4. Comparison example (cmp)
+-------------------------------
+
+A configuration made for comparison purposes with other tracing implementations.
+It uses a simplified span hierarchy without context propagation.
+
+--- test/cmp/otel.cfg (excerpt) ----------------------------------------
+
+    otel-scope client_session_start
+        span "HAProxy session" root
+            baggage "haproxy_id" var(sess.otel.uuid)
+        span "Client session" parent "HAProxy session"
+        otel-event on-client-session-start
+
+    otel-scope http_response-error
+        span "HTTP response"
+            status "error" str("!acl-http-status-ok")
+        otel-event on-http-response if !acl-http-status-ok
+
+    otel-scope server_session_end
+        finish "HTTP response" "Server session"
+        otel-event on-http-response
+
+    otel-scope client_session_end
+        finish "*"
+        otel-event on-http-response
+
+---------------------------------------------------------------------
+
+
+6.5. Empty / minimal example (empty)
+--------------------------------------
+
+The minimal valid OTel configuration.  The filter is initialized but no events
+are triggered:
+
+--- test/empty/otel.cfg -------------------------------------------------
+
+  otel-instrumentation otel-test-instrumentation
+      config empty/otel.yml
+
+---------------------------------------------------------------------
+
+This is useful for testing the OTel filter initialization behavior without any
+actual telemetry processing.

addons/otel/README-design

@@ -0,0 +1,725 @@
+OpenTelemetry filter -- design patterns
+==========================================================================
+
+This document describes the cross-cutting design patterns used throughout
+the OTel filter implementation.  It complements README-implementation
+(component-by-component architecture) with a pattern-oriented view of the
+mechanisms that span multiple source files.
+
+
+1  X-Macro Code Generation
+----------------------------------------------------------------------
+
+The filter uses X-macro lists extensively to generate enums, keyword tables,
+event metadata and configuration init/free functions from a single definition.
+Each X-macro list is a preprocessor define containing repeated invocations of
+a helper macro whose name is supplied by the expansion context.
+
+1.1  Event Definitions
+
+FLT_OTEL_EVENT_DEFINES (event.h) drives the event system.  Each entry has the
+form:
+
+  FLT_OTEL_EVENT_DEF(NAME, CHANNEL, REQ_AN, RES_AN, HTTP_INJ, "string")
+
+The same list is expanded twice:
+
+  - In enum FLT_OTEL_EVENT_enum (event.h) to produce symbolic constants
+    (FLT_OTEL_EVENT_NONE, FLT_OTEL_EVENT_REQ_STREAM_START, etc.) followed by
+    the FLT_OTEL_EVENT_MAX sentinel.
+
+  - In the flt_otel_event_data[] initializer (event.c) to produce a const table
+    of struct flt_otel_event_data entries carrying the analyzer bit, sample
+    fetch direction, valid fetch locations, HTTP injection flag and event name
+    string.
+
+Adding a new event requires a single line in the X-macro list.
+
+1.2  Parser Keyword Definitions
+
+Three X-macro lists drive the configuration parser:
+
+  FLT_OTEL_PARSE_INSTR_DEFINES   (parser.h, 9 keywords)
+  FLT_OTEL_PARSE_GROUP_DEFINES   (parser.h, 2 keywords)
+  FLT_OTEL_PARSE_SCOPE_DEFINES   (parser.h, 15 keywords)
+
+Each entry has the form:
+
+  FLT_OTEL_PARSE_DEF(ENUM, flag, check, min, max, "name", "usage")
+
+Each list is expanded to:
+
+  - An enum for keyword indices (FLT_OTEL_PARSE_INSTR_ID, etc.).
+  - A static parse_data[] table of struct flt_otel_parse_data entries carrying
+    the keyword index, flag_check_id, check_name type, argument count bounds,
+    keyword name string and usage string.
+
+The section parsers (flt_otel_parse_cfg_instr, _group, _scope) look up args[0]
+in their parse_data table via flt_otel_parse_cfg_check(), which validates
+argument counts and character constraints before dispatching to
+the keyword-specific handler.
+
+Additional X-macro lists generate:
+
+  FLT_OTEL_PARSE_SCOPE_STATUS_DEFINES      Span status codes.
+  FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEFINES  Instrument type keywords.
+  FLT_OTEL_HTTP_METH_DEFINES               HTTP method name table.
+  FLT_OTEL_GROUP_DEFINES                   Group action metadata.
+
+1.3  Configuration Init/Free Generation
+
+Two macros in conf_funcs.h generate init and free functions for all
+configuration structure types:
+
+  FLT_OTEL_CONF_FUNC_INIT(_type_, _id_, _func_)
+  FLT_OTEL_CONF_FUNC_FREE(_type_, _id_, _func_)
+
+The _type_ parameter names the structure (e.g. "span"), _id_ names the
+identifier field within the FLT_OTEL_CONF_HDR (e.g. "id", "key", "str"), and
+_func_ is a brace-enclosed code block executed after the boilerplate allocation
+(for init) or before the boilerplate teardown (for free).
+
+The generated init function:
+  1. Validates the identifier is non-NULL and non-empty.
+  2. Checks the length against FLT_OTEL_ID_MAXLEN (64).
+  3. Detects duplicates in the target list.
+  4. Handles auto-generated IDs (FLT_OTEL_CONF_HDR_SPECIAL prefix).
+  5. Allocates with OTELC_CALLOC, duplicates the ID with OTELC_STRDUP.
+  6. Appends to the parent list via LIST_APPEND.
+  7. Executes the custom _func_ body.
+
+The generated free function:
+  1. Executes the custom _func_ body (typically list destruction).
+  2. Frees the identifier string.
+  3. Removes the node from its list.
+  4. Frees the structure with OTELC_SFREE_CLEAR.
+
+conf.c instantiates these macros for all 13 configuration types: hdr, str, ph,
+sample_expr, sample, link, context, span, scope, instrument, log_record, group,
+instr.  The more complex types (span, scope, instr) carry non-trivial _func_
+bodies that initialize sub-lists or set default values.
+
+
+2  Type-Safe Generic Macros
+----------------------------------------------------------------------
+
+define.h provides utility macros that use typeof() and statement expressions
+for type-safe generic programming without C++ templates.
+
+2.1  Safe Pointer Dereferencing
+
+  FLT_OTEL_PTR_SAFE(a, b)
+    Returns 'a' if non-NULL, otherwise the default value 'b'.  Uses typeof(*(a))
+    to verify type compatibility at compile time.
+
+  FLT_OTEL_DEREF(p, m, v)
+    Safely dereferences p->m, returning 'v' if 'p' is NULL.
+
+  FLT_OTEL_DDEREF(a, m, v)
+    Safely double-dereferences *a->m, returning 'v' if either 'a' or '*a' is
+    NULL.
+
+These macros eliminate repetitive NULL checks while preserving the correct
+pointer types through typeof().
+
+2.2  String Comparison
+
+  FLT_OTEL_STR_CMP(S, s)
+    Compares a runtime string 's' against a compile-time string literal 'S'.
+    Expands to a call with the literal's address and computed length, avoiding
+    repeated strlen() on known constants.
+
+  FLT_OTEL_CONF_STR_CMP(s, S)
+    Compares two configuration strings using their cached length fields (from
+    FLT_OTEL_CONF_STR / FLT_OTEL_CONF_HDR).  Falls through to memcmp() only when
+    lengths match, providing an early-out fast path.
+
+2.3  List Operations
+
+  FLT_OTEL_LIST_ISVALID(a)
+    Checks whether a list head has been initialized (both prev and next are
+    non-NULL).
+
+  FLT_OTEL_LIST_DEL(a)
+    Safely deletes a list element only if the list head is valid.
+
+  FLT_OTEL_LIST_DESTROY(t, h)
+    Destroys all elements in a typed configuration list by iterating with
+    list_for_each_entry_safe and calling flt_otel_conf_<t>_free() for each
+    entry.  The type 't' is used to derive both the structure type and the
+    free function name.
+
+2.4  Thread-Local Rotating Buffers
+
+  FLT_OTEL_BUFFER_THR(b, m, n, p)
+    Declares a thread-local pool of 'n' string buffers, each of size 'm'.
+    The pool index rotates on each invocation, avoiding the need for explicit
+    allocation in debug formatting functions.  Each call returns a pointer to
+    the next buffer via the output parameter 'p'.
+
+    Used primarily in debug-only functions (flt_otel_analyzer,
+    flt_otel_list_dump) where temporary strings must survive until their caller
+    finishes with them.
+
+
+3  Error Handling Architecture
+----------------------------------------------------------------------
+
+3.1  Error Accumulation Macros
+
+Three macros in define.h manage error messages:
+
+  FLT_OTEL_ERR(f, ...)
+    Formats an error message via memprintf() into the caller's char **err
+    pointer, but only if *err is still NULL.  Prevents overwriting the first
+    error with a cascading secondary error.
+
+  FLT_OTEL_ERR_APPEND(f, ...)
+    Unconditionally appends to the error message regardless of prior content.
+    Used when a function must report multiple issues.
+
+  FLT_OTEL_ERR_FREE(p)
+    Logs the accumulated error message at WARNING level via FLT_OTEL_ALERT,
+    then frees the string and NULLs the pointer.
+
+All source functions that can fail accept a char **err parameter.  The
+convention is: set *err on error, leave it alone on success.  Callers check
+both the return value and *err to detect problems.
+
+3.2  Parse-Time Error Reporting
+
+Configuration parsing (parser.c) uses additional macros:
+
+  FLT_OTEL_PARSE_ERR(e, f, ...)
+    Sets the error string and ORs ERR_ABORT | ERR_ALERT into the return value.
+    Used inside section parser switch statements.
+
+  FLT_OTEL_PARSE_ALERT(f, ...)
+    Issues a ha_alert() with the current file and line, then sets the error
+    flags.  Used when the error message should appear immediately.
+
+  FLT_OTEL_POST_PARSE_ALERT(f, ...)
+    Same as PARSE_ALERT but uses cfg_file instead of file, for post-parse
+    validation that runs after the parser has moved on.
+
+  FLT_OTEL_PARSE_IFERR_ALERT()
+    Checks whether *err was set by a called function, and if so, issues an
+    alert and clears the error.  This bridges between functions that use the
+    char **err convention and the parser's own alert mechanism.
+
+3.3  Runtime Error Modes
+
+Two helper functions in filter.c implement the runtime error policy:
+
+  flt_otel_return_int(f, err, retval)
+  flt_otel_return_void(f, err)
+
+If an error is detected (retval == FLT_OTEL_RET_ERROR or *err != NULL):
+
+  Hard-error mode (rt_ctx->flag_harderr):
+    Sets rt_ctx->flag_disabled = 1, disabling the filter for the remainder of
+    the stream.  Atomically increments the disabled counter.  The error is
+    logged as "filter hard-error (disabled)".
+
+  Soft-error mode (default):
+    The error is logged as "filter soft-error" and processing continues.  The
+    tracing data for the current event may be incomplete but the stream is not
+    affected.
+
+In both modes, FLT_OTEL_RET_OK is always returned to HAProxy.  A tracing failure
+never interrupts stream processing.
+
+3.4  Disabled State Checking
+
+flt_otel_is_disabled() (filter.c) is called at the top of every filter callback
+that processes events.  It checks three conditions:
+
+  1. rt_ctx is NULL (filter was never attached or already detached).
+  2. rt_ctx->flag_disabled is set (hard-error disabled the filter).
+  3. conf->instr->flag_disabled is set (globally disabled via CLI).
+
+All three are loaded via _HA_ATOMIC_LOAD() for thread safety.  When disabled,
+the callback returns immediately without processing.
+
+
+4  Thread Safety Model
+----------------------------------------------------------------------
+
+The filter runs within HAProxy's multi-threaded worker model.  Each stream is
+bound to a single thread, so per-stream state (the runtime context, spans and
+contexts) is accessed without locking.  Cross-stream shared state uses atomic
+operations.
+
+4.1  Atomic Fields
+
+The following fields are accessed atomically across threads:
+
+  conf->instr->flag_disabled  Toggled by CLI "otel enable/disable".  Checked in
+                              flt_otel_ops_attach() and flt_otel_is_disabled().
+
+  conf->instr->flag_harderr   Toggled by CLI "otel hard-errors/soft-errors".
+                              Copied to rt_ctx at attach time.
+
+  conf->instr->rate_limit     Set by CLI "otel rate".
+                              Read in flt_otel_ops_attach().
+
+  conf->instr->logging        Set by CLI "otel logging".
+                              Copied to rt_ctx at attach time.
+
+  flt_otel_drop_cnt           Incremented in flt_otel_log_handler_cb().
+                              Read by CLI "otel status".
+
+  conf->cnt.disabled[]        Incremented in flt_otel_return_int/void().
+  conf->cnt.attached[]        Incremented in flt_otel_ops_attach().
+
+All use _HA_ATOMIC_LOAD(), _HA_ATOMIC_STORE(), _HA_ATOMIC_INC() or
+_HA_ATOMIC_ADD() from HAProxy's atomic primitives.
+
+4.2  Metric Instrument Creation (CAS Pattern)
+
+Metric instruments are shared across all threads but created lazily on first
+use.  The creation uses a compare-and-swap pattern to ensure exactly one thread
+performs the creation:
+
+  int64_t expected = OTELC_METRIC_INSTRUMENT_UNSET;  /* -1 */
+  if (HA_ATOMIC_CAS(&instr->idx, &expected, OTELC_METRIC_INSTRUMENT_PENDING)) {
+      /* This thread won the race -- create the instrument. */
+      idx = meter->create_instrument(...);
+      HA_ATOMIC_STORE(&instr->idx, idx);
+  }
+
+The three states are:
+  UNSET   (-1)  Not yet created.  The CAS target.
+  PENDING (-2)  Creation in progress by another thread.
+  >= 0          Valid meter index.  Ready for recording.
+
+Threads that lose the CAS skip creation.  Update-form instruments check that the
+referenced create-form's idx is >= 0 before recording; if it is still PENDING or
+UNSET, the measurement is silently skipped.
+
+4.3  Per-Thread Initialization Guard
+
+flt_otel_ops_init_per_thread() uses the FLT_CFG_FL_HTX flag on fconf as a
+one-shot guard: the tracer, meter and logger background threads are started only
+on the first call.  Subsequent calls from other proxies sharing the same filter
+configuration skip the start sequence.
+
+4.4  CLI Update Propagation
+
+CLI set commands (cli.c) iterate all OTel filter instances across all proxies
+using the FLT_OTEL_PROXIES_LIST_START / FLT_OTEL_PROXIES_LIST_END macros
+(util.h) and atomically update the target field on each instance.  This ensures
+that "otel disable" takes effect globally, not just on one proxy.
+
+
+5  Sample Evaluation Pipeline
+----------------------------------------------------------------------
+
+Sample expressions bridge HAProxy's runtime data (headers, variables, connection
+properties) into OTel attributes, events, baggage, status, metric values and log
+record bodies.
+
+5.1  Two Evaluation Paths
+
+The parser detects which path to use based on the presence of "%[" in the sample
+value argument:
+
+  Log-format path (sample->lf_used == true):
+    The value is parsed via parse_logformat_string() and stored in
+    sample->lf_expr.  At runtime, build_logline() evaluates the expression into
+    a temporary buffer of global.tune.bufsize bytes.  The result is always a
+    string.
+
+  Bare sample path (sample->lf_used == false):
+    Each whitespace-separated token is parsed via sample_parse_expr() and
+    stored as an flt_otel_conf_sample_expr in sample->exprs.  At runtime, each
+    expression is evaluated via sample_process().  If there is exactly one
+    expression, the native HAProxy sample type is preserved (bool, int, IP
+    address, string).  If there are multiple expressions, their string
+    representations are concatenated.
+
+5.2  Type Conversion Chain
+
+flt_otel_sample_to_value() (util.c) converts HAProxy sample types to OTel value
+types:
+
+  SMP_T_BOOL  ->  OTELC_VALUE_BOOL
+  SMP_T_SINT  ->  OTELC_VALUE_INT64
+  Other       ->  OTELC_VALUE_DATA (string, via flt_otel_sample_to_str)
+
+flt_otel_sample_to_str() handles the string conversion for non-trivial types:
+
+  SMP_T_BOOL     "0" or "1"
+  SMP_T_SINT     snprintf decimal
+  SMP_T_IPV4     inet_ntop
+  SMP_T_IPV6     inet_ntop
+  SMP_T_STR      direct copy
+  SMP_T_METH     lookup from static HTTP method table, or raw string for
+                 HTTP_METH_OTHER
+
+For metric instruments, string values are rejected -- the meter requires
+OTELC_VALUE_INT64.  If the sample evaluates to a string, otelc_value_strtonum()
+attempts numeric conversion as a last resort.
+
+5.3  Dispatch to Data Structures
+
+flt_otel_sample_add() (util.c) is the top-level evaluator.  After converting the
+sample to an otelc_value, it dispatches based on type:
+
+  FLT_OTEL_EVENT_SAMPLE_ATTRIBUTE
+    -> flt_otel_sample_add_kv(&data->attributes, key, &value)
+
+  FLT_OTEL_EVENT_SAMPLE_BAGGAGE
+    -> flt_otel_sample_add_kv(&data->baggage, key, &value)
+
+  FLT_OTEL_EVENT_SAMPLE_EVENT
+    -> flt_otel_sample_add_event(&data->events, sample, &value)
+       Groups attributes by event name; creates a new flt_otel_scope_data_event
+       node if the event name is not yet present.
+
+  FLT_OTEL_EVENT_SAMPLE_STATUS
+    -> flt_otel_sample_set_status(&data->status, sample, &value, err)
+       Sets the status code from sample->extra.num and the description from the
+       evaluated value.  Rejects duplicate status settings.
+
+5.4  Growable Key-Value Arrays
+
+Attribute and baggage arrays use a lazy-allocation / grow-on-demand pattern via
+flt_otel_sample_add_kv() (util.c):
+
+  - Initial allocation: FLT_OTEL_ATTR_INIT_SIZE (8) elements via otelc_kv_new().
+  - Growth: FLT_OTEL_ATTR_INC_SIZE (4) additional elements via otelc_kv_resize()
+    when the array is full.
+  - The cnt field tracks used elements; size tracks total capacity.
+
+Event attribute arrays follow the same pattern within each
+flt_otel_scope_data_event node.
+
+
+6  Rate Limiting and Filtering
+----------------------------------------------------------------------
+
+6.1  Rate Limit Representation
+
+The rate limit is configured as a floating-point percentage (0.0 to 100.0) but
+stored internally as a uint32_t for lock-free comparison:
+
+  FLT_OTEL_FLOAT_U32(a)  Converts a percentage to a uint32 value:
+                          (uint32_t)((a / 100.0) * UINT32_MAX)
+
+  FLT_OTEL_U32_FLOAT(a)  Converts back for display:
+                          ((double)(a) / UINT32_MAX) * 100.0
+
+At attach time, the filter compares a fresh ha_random32() value against the
+stored rate_limit.  If the random value exceeds the threshold, the filter
+returns FLT_OTEL_RET_IGNORE and does not attach to the stream.  This provides
+uniform sampling without floating-point arithmetic on the hot path.
+
+6.2  ACL-Based Filtering
+
+Each scope may carry an ACL condition (if/unless) evaluated at scope
+execution time via acl_exec_cond().  ACL references are resolved through
+a priority chain in flt_otel_parse_acl() (parser.c):
+
+  1. Scope-local ACLs (declared within the otel-scope section).
+  2. Instrumentation ACLs (declared in the otel-instrumentation section).
+  3. Proxy ACLs (declared in the HAProxy frontend/backend section).
+
+The first list that produces a successful build_acl_cond() result is used.
+If the condition fails at runtime:
+
+  - If the scope contains a root span, the entire stream is disabled
+    (rt_ctx->flag_disabled = 1) to avoid orphaned child spans.
+  - Otherwise, the scope is simply skipped.
+
+6.3  Global Disable
+
+The filter can be disabled globally via the CLI ("otel disable") or the
+configuration ("option disabled").  The flag_disabled field on the
+instrumentation configuration is checked atomically in flt_otel_ops_attach()
+before any per-stream allocation occurs.
+
+
+7  Memory Management Strategy
+----------------------------------------------------------------------
+
+7.1  Pool-Based Allocation
+
+Four HAProxy memory pools are registered for frequently allocated structures
+(pool.c):
+
+  pool_head_otel_scope_span       Per-stream span entries.
+  pool_head_otel_scope_context    Per-stream context entries.
+  pool_head_otel_runtime_context  Per-stream runtime context.
+  pool_head_otel_span_context     OTel SDK objects (via C wrapper allocator
+                                  callback).
+
+Pool registration is conditional on compile-time flags (USE_POOL_OTEL_* in
+config.h).  flt_otel_pool_alloc() attempts pool allocation first and falls back
+to heap allocation (OTELC_MALLOC) when the pool is NULL or the requested size
+exceeds the pool's element size.
+
+The C wrapper library's memory allocations are redirected through
+flt_otel_mem_malloc() / flt_otel_mem_free() (filter.c), which use the
+otel_span_context pool via otelc_ext_init().  This keeps OTel SDK objects in
+HAProxy's pool allocator for cache-friendly allocation.
+
+7.2  Trash Buffers
+
+flt_otel_trash_alloc() (pool.c) provides temporary scratch buffers of
+global.tune.bufsize bytes.  When USE_TRASH_CHUNK is defined, it uses HAProxy's
+alloc_trash_chunk(); otherwise it manually allocates a buffer structure and data
+area.  Trash buffers are used for:
+
+  - Log-format evaluation in metric recording and log record emission.
+  - HTTP header name construction in flt_otel_http_header_set().
+  - Temporary string assembly in sample evaluation.
+
+7.3  Scope Data Lifecycle
+
+flt_otel_scope_data (scope.h) is initialized and freed within a single span
+processing block in flt_otel_scope_run().  It is stack-conceptual data:
+allocated at the start of each span's processing, populated during sample
+evaluation, consumed by flt_otel_scope_run_span(), and freed immediately after.
+The key-value arrays within it are heap-allocated via otelc_kv_new() and freed
+via otelc_kv_destroy().
+
+
+8  Context Propagation Mechanism
+----------------------------------------------------------------------
+
+8.1  Carrier Abstraction
+
+The OTel C wrapper uses a carrier pattern for context propagation.  Two carrier
+types exist, each with writer and reader variants:
+
+  otelc_text_map_writer / otelc_text_map_reader
+  otelc_http_headers_writer / otelc_http_headers_reader
+
+otelc.c provides callback functions that the C wrapper invokes during
+inject/extract operations:
+
+  Injection (writer callbacks):
+    flt_otel_text_map_writer_set_cb()
+    flt_otel_http_headers_writer_set_cb()
+    Both append key-value pairs to the carrier's text_map via
+    OTELC_TEXT_MAP_ADD.
+
+  Extraction (reader callbacks):
+    flt_otel_text_map_reader_foreach_key_cb()
+    flt_otel_http_headers_reader_foreach_key_cb()
+    Both iterate the text_map's key-value pairs, invoking a handler function
+    for each entry.  Iteration stops early if the handler returns -1.
+
+8.2  HTTP Header Storage
+
+flt_otel_http_headers_get() (http.c) reads headers from the HTX buffer with
+prefix matching.  The prefix is stripped from header names in the returned
+text_map.  A special prefix character ('-') matches all headers without prefix
+filtering.
+
+flt_otel_http_header_set() constructs a "prefix-name" header, removes all
+existing occurrences via an http_find_header / http_remove_header loop, then
+adds the new value via http_add_header.
+
+8.3  Variable Storage
+
+When USE_OTEL_VARS is enabled, span context can also be stored in HAProxy
+transaction-scoped variables.  Variable names are normalized
+(flt_otel_normalize_name in vars.c):
+
+  Dashes    -> 'D'  (FLT_OTEL_VAR_CHAR_DASH)
+  Spaces    -> 'S'  (FLT_OTEL_VAR_CHAR_SPACE)
+  Uppercase -> lowercase
+
+Full variable names are constructed as "scope.prefix.name" with dots as
+component separators.
+
+Two implementation paths exist based on the USE_OTEL_VARS_NAME compile flag:
+
+  With USE_OTEL_VARS_NAME:
+    A binary tracking buffer (stored as a HAProxy variable) records the names
+    of all context variables.  flt_otel_ctx_loop() iterates length-prefixed
+    entries in this buffer, calling a callback for each.  This enables efficient
+    enumeration without scanning the full variable store.
+
+  Without USE_OTEL_VARS_NAME:
+    Direct CEB tree traversal on the HAProxy variable store with prefix
+    matching.  This is simpler but potentially slower for large variable sets.
+
+The choice is auto-detected at build time by checking whether struct var has
+a 'name' member.
+
+
+9  Debug Infrastructure
+----------------------------------------------------------------------
+
+9.1  Conditional Compilation
+
+When OTEL_DEBUG=1 is set at build time, -DDEBUG_OTEL is added to the compiler
+flags.  This enables:
+
+  - Additional flt_ops callbacks: deinit_per_thread, http_payload, http_reset,
+    tcp_payload.  In non-debug builds these are NULL.
+
+  - FLT_OTEL_USE_COUNTERS (config.h), which activates the per-event counters in
+    flt_otel_counters (attached[], disabled[] arrays).
+
+  - Debug-only functions throughout the codebase, marked with [D] in
+    README-func: flt_otel_scope_data_dump, flt_otel_http_headers_dump,
+    flt_otel_vars_dump, flt_otel_args_dump, flt_otel_filters_dump, etc.
+
+  - The OTELC_DBG() macro for level-gated debug output.
+
+9.2  Debug Level Bitmask
+
+The debug level is a uint stored in conf->instr and controllable at runtime via
+"otel debug <level>".  The default value is FLT_OTEL_DEBUG_LEVEL (0b11101111111
+in config.h).  Each bit enables a category of debug output.
+
+9.3  Logging Integration
+
+The FLT_OTEL_LOG macro (debug.h) integrates with HAProxy's send_log() system.
+Its behavior depends on the logging flags:
+
+  FLT_OTEL_LOGGING_OFF (0):
+    No log messages are emitted.
+
+  FLT_OTEL_LOGGING_ON (1 << 0):
+    Log messages are sent to the log servers configured in the instrumentation
+    block via parse_logger().
+
+  FLT_OTEL_LOGGING_NOLOGNORM (1 << 1):
+    Combined with ON, suppresses normal-level messages (only warnings and above
+    are emitted).
+
+These flags are set via the "option dontlog-normal" configuration keyword or the
+"otel logging" CLI command.
+
+9.4  Counter System
+
+When FLT_OTEL_USE_COUNTERS is defined, the flt_otel_counters structure (conf.h)
+maintains:
+
+  attached[4]   Counters for attach outcomes, incremented atomically in
+                flt_otel_ops_attach().
+  disabled[2]   Counters for hard-error disables, incremented atomically in
+                flt_otel_return_int() / flt_otel_return_void().
+
+The counters are reported by the "otel status" CLI command and dumped at deinit
+time in debug builds.
+
+
+10  Idle Timeout Mechanism
+----------------------------------------------------------------------
+
+The idle timeout fires periodic events on idle streams, enabling heartbeat-style
+span updates or metric recordings.
+
+10.1  Configuration
+
+Each otel-scope bound to the "on-idle-timeout" event must declare an
+idle-timeout interval.  At check time (flt_otel_ops_check), the minimum idle
+timeout across all scopes is stored in conf->instr->idle_timeout.
+
+10.2  Initialization
+
+In flt_otel_ops_stream_start(), the runtime context's idle_timeout and idle_exp
+fields are initialized from the precomputed minimum.  The expiration tick is
+merged into the request channel's analyse_exp to ensure the stream task wakes
+at the right time.
+
+10.3  Firing
+
+flt_otel_ops_check_timeouts() checks tick_is_expired(rt_ctx->idle_exp).
+When expired:
+  - The on-idle-timeout event fires via flt_otel_event_run().
+  - The timer is rescheduled for the next interval.
+  - If analyse_exp itself has expired (which would cause a tight loop), it is
+    reset before the new idle_exp is merged.
+  - STRM_EVT_MSG is set on stream->pending_events to ensure the stream is
+    re-evaluated.
+
+
+11  Group Action Integration Pattern
+----------------------------------------------------------------------
+
+The "otel-group" action integrates OTel scopes with HAProxy's rule system
+(http-request, http-response, http-after-response, tcp-request, tcp-response).
+
+11.1  Registration
+
+group.c registers action keywords via INITCALL1 macros for all five action
+contexts.  Each registration points to flt_otel_group_parse() as the parse
+function.
+
+11.2  Parse-Check-Execute Cycle
+
+  Parse (flt_otel_group_parse):
+    Stores the filter ID and group ID as string duplicates in rule->arg.act.p[].
+    Sets the check, action and release callbacks.
+
+  Check (flt_otel_group_check):
+    Resolves the string IDs to configuration pointers by scanning the proxy's
+    filter list.  Replaces the string pointers with resolved flt_conf,
+    flt_otel_conf and flt_otel_conf_ph pointers.  Frees the original string
+    duplicates.
+
+  Execute (flt_otel_group_action):
+    Finds the filter instance in the stream's filter list.  Validates rule->from
+    against the flt_otel_group_data[] table to determine the sample fetch
+    direction and valid fetch locations.  Iterates all scopes in the group and
+    calls flt_otel_scope_run() for each.  Always returns ACT_RET_CONT -- a group
+    action never interrupts rule processing.
+
+11.3  Group Data Table
+
+The flt_otel_group_data[] table (group.c) maps each HAProxy action context
+(ACT_F_*) to:
+
+  act_from     The action context enum value.
+  smp_val      The valid sample fetch location (FE or BE).
+  smp_opt_dir  The sample fetch direction (REQ or RES).
+
+This table is generated from the FLT_OTEL_GROUP_DEFINES X-macro list (group.h).
+
+
+12  CLI Runtime Control Architecture
+----------------------------------------------------------------------
+
+cli.c registers commands under the "otel" prefix.  The command table maps
+keyword sequences to handler functions with access level requirements.
+
+12.1  Command Table
+
+  "otel status"       No access restriction.  Read-only status report.
+  "otel enable"       ACCESS_LVL_ADMIN.  Clears flag_disabled.
+  "otel disable"      ACCESS_LVL_ADMIN.  Sets flag_disabled.
+  "otel hard-errors"  ACCESS_LVL_ADMIN.  Sets flag_harderr.
+  "otel soft-errors"  ACCESS_LVL_ADMIN.  Clears flag_harderr.
+  "otel logging"      ACCESS_LVL_ADMIN for setting; any for reading.
+  "otel rate"         ACCESS_LVL_ADMIN for setting; any for reading.
+  "otel debug"        ACCESS_LVL_ADMIN.  DEBUG_OTEL only.
+
+The "otel enable" and "otel disable" commands share the same handler
+(flt_otel_cli_parse_disabled) with the private argument distinguishing the
+operation (1 for disable, 0 for enable).  The same pattern is used for
+hard-errors / soft-errors.
+
+12.2  Global Propagation
+
+All set operations iterate every OTel filter instance across all proxies using
+FLT_OTEL_PROXIES_LIST_START / FLT_OTEL_PROXIES_LIST_END macros and atomically
+update the target field.  A single "otel disable" command disables the filter
+in every proxy that has it configured.
+
+12.3  Status Report
+
+The "otel status" command assembles a dynamic string via memprintf() containing:
+
+  - Library versions (C++ SDK and C wrapper).
+  - Debug level (DEBUG_OTEL only).
+  - Dropped diagnostic message count.
+  - Per-proxy: config file, group/scope counts, instrumentation details, rate
+    limit, error mode, disabled state, logging state, analyzer bitmask, and
+    counters (if FLT_OTEL_USE_COUNTERS).

addons/otel/README-func

@@ -0,0 +1,723 @@
+OpenTelemetry filter -- function reference
+==========================================================================
+
+Functions are grouped by source file.  Functions marked with [D] are only
+compiled when DEBUG_OTEL is defined.
+
+
+src/filter.c
+----------------------------------------------------------------------
+
+Filter lifecycle callbacks and helpers registered in flt_otel_ops.
+
+  flt_otel_mem_malloc
+      Allocator callback for the OTel C wrapper library.  Uses the HAProxy
+      pool_head_otel_span_context pool.
+
+  flt_otel_mem_free
+      Deallocator callback for the OTel C wrapper library.
+
+  flt_otel_log_handler_cb
+      Diagnostic callback for the OTel C wrapper library.  Counts SDK internal
+      diagnostic messages.
+
+  flt_otel_thread_id
+      Returns the current HAProxy thread ID (tid).
+
+  flt_otel_lib_init
+      Initializes the OTel C wrapper library: verifies the library version,
+      constructs the configuration path, calls otelc_init(), and creates the
+      tracer, meter and logger instances.
+
+  flt_otel_is_disabled
+      Checks whether the filter instance is disabled for the current stream.
+      Logs the event name when DEBUG_OTEL is enabled.
+
+  flt_otel_return_int
+      Error handler for callbacks returning int.  In hard-error mode, disables
+      the filter; in soft-error mode, clears the error and returns OK.
+
+  flt_otel_return_void
+      Error handler for callbacks returning void.  Same logic as
+      flt_otel_return_int but without a return value.
+
+  flt_otel_ops_init
+      Filter init callback (flt_ops.init).  Called once per proxy to initialize
+      the OTel library via flt_otel_lib_init() and register CLI keywords.
+
+  flt_otel_ops_deinit
+      Filter deinit callback (flt_ops.deinit).  Destroys the tracer, meter and
+      logger, frees the configuration, and calls otelc_deinit().
+
+  flt_otel_ops_check
+      Filter check callback (flt_ops.check).  Validates the parsed
+      configuration: checks for duplicate filter IDs, resolves group/scope
+      placeholder references, verifies root span count, and sets analyzer bits.
+
+  flt_otel_ops_init_per_thread
+      Per-thread init callback (flt_ops.init_per_thread).  Starts the OTel
+      tracer thread and enables HTX filtering.
+
+  flt_otel_ops_deinit_per_thread [D]
+      Per-thread deinit callback (flt_ops.deinit_per_thread).
+
+  flt_otel_ops_attach
+      Filter attach callback (flt_ops.attach).  Called when a filter instance is
+      attached to a stream.  Applies rate limiting, creates the runtime context,
+      and sets analyzer bits.
+
+  flt_otel_ops_stream_start
+      Stream start callback (flt_ops.stream_start).  Fires the
+      on-stream-start event before any channel processing begins.  The channel
+      argument is NULL.  After the event, initializes the idle timer in the
+      runtime context from the precomputed minimum idle_timeout in the
+      instrumentation configuration.
+
+  flt_otel_ops_stream_set_backend
+      Stream set-backend callback (flt_ops.stream_set_backend).  Fires the
+      on-backend-set event when a backend is assigned to the stream.
+
+  flt_otel_ops_stream_stop
+      Stream stop callback (flt_ops.stream_stop).  Fires the
+      on-stream-stop event after all channel processing ends.  The channel
+      argument is NULL.
+
+  flt_otel_ops_detach
+      Filter detach callback (flt_ops.detach).  Frees the runtime context when
+      the filter is detached from a stream.
+
+  flt_otel_ops_check_timeouts
+      Timeout callback (flt_ops.check_timeouts).  When the idle-timeout timer
+      has expired, fires the on-idle-timeout event and reschedules the timer
+      for the next interval.  Sets the STRM_EVT_MSG pending event flag on the
+      stream.
+
+  flt_otel_ops_channel_start_analyze
+      Channel start-analyze callback.  Registers analyzers on the channel and
+      runs the client/server session start event.  Propagates the idle-timeout
+      expiry to the channel's analyse_exp so the stream task keeps waking.
+
+  flt_otel_ops_channel_pre_analyze
+      Channel pre-analyze callback.  Maps the analyzer bit to an event index and
+      runs the corresponding event.
+
+  flt_otel_ops_channel_post_analyze
+      Channel post-analyze callback.  Non-resumable; called once when a
+      filterable analyzer finishes.
+
+  flt_otel_ops_channel_end_analyze
+      Channel end-analyze callback.  Runs the client/server session end event.
+      For the request channel, also fires the server-unavailable event if no
+      response was processed.
+
+  flt_otel_ops_http_headers
+      HTTP headers callback (flt_ops.http_headers).  Fires
+      on-http-headers-request or on-http-headers-response depending on the
+      channel direction.
+
+  flt_otel_ops_http_payload [D]
+      HTTP payload callback (flt_ops.http_payload).
+
+  flt_otel_ops_http_end
+      HTTP end callback (flt_ops.http_end).  Fires on-http-end-request or
+      on-http-end-response depending on the channel direction.
+
+  flt_otel_ops_http_reset [D]
+      HTTP reset callback (flt_ops.http_reset).
+
+  flt_otel_ops_http_reply
+      HTTP reply callback (flt_ops.http_reply).  Fires the on-http-reply event
+      when HAProxy generates an internal reply.
+
+  flt_otel_ops_tcp_payload [D]
+      TCP payload callback (flt_ops.tcp_payload).
+
+
+src/event.c
+----------------------------------------------------------------------
+
+Event dispatching, metrics recording and scope/span execution engine.
+
+  flt_otel_scope_run_instrument_record
+      Records a measurement for a synchronous metric instrument.  Evaluates
+      update-form attributes via flt_otel_sample_eval() and
+      flt_otel_sample_add_kv(), evaluates the sample expression from the
+      create-form instrument (instr_ref), and submits the value to the meter
+      via update_instrument_kv_n().
+
+  flt_otel_scope_run_instrument
+      Processes all metric instruments for a scope.  Runs in two passes: the
+      first lazily creates create-form instruments via the meter, using
+      HA_ATOMIC_CAS to guarantee thread-safe one-time initialization; the second
+      iterates update-form instruments and records measurements via
+      flt_otel_scope_run_instrument_record().  Instruments whose index is still
+      negative (UNUSED or PENDING) are skipped.
+
+  flt_otel_scope_run_log_record
+      Emits log records for a scope.  Iterates over the configured log-record
+      list, skipping entries whose severity is below the logger threshold.
+      Evaluates the body from sample fetch expressions or a log-format string,
+      optionally resolves a span reference against the runtime context, and
+      emits the record via the logger.  A missing span is non-fatal -- the
+      record is emitted without span correlation.
+
+  flt_otel_scope_run_span
+      Executes a single span: creates the OTel span on first call, adds links,
+      baggage, attributes, events and status, then injects the context into HTTP
+      headers or HAProxy variables.
+
+  flt_otel_scope_run
+      Executes a complete scope: evaluates ACL conditions, extracts contexts,
+      iterates over configured spans (resolving links, evaluating sample
+      expressions), calls flt_otel_scope_run_span for each, processes metric
+      instruments via flt_otel_scope_run_instrument(), emits log records via
+      flt_otel_scope_run_log_record(), then marks and finishes completed spans.
+
+  flt_otel_event_run
+      Top-level event dispatcher.  Called from filter callbacks, iterates over
+      all scopes matching the event index and calls flt_otel_scope_run() for
+      each.
+
+
+src/scope.c
+----------------------------------------------------------------------
+
+Runtime context, span and context lifecycle management.
+
+  flt_otel_pools_info [D]
+      Logs the sizes of all registered HAProxy memory pools used by the OTel
+      filter.
+
+  flt_otel_runtime_context_init
+      Allocates and initializes the per-stream runtime context.  Generates a
+      UUID and stores it in the sess.otel.uuid HAProxy variable.
+
+  flt_otel_runtime_context_free
+      Frees the runtime context: ends all active spans, destroys all extracted
+      contexts, and releases pool memory.
+
+  flt_otel_scope_span_init
+      Finds an existing scope span by name or creates a new one.  Resolves the
+      parent reference (span or extracted context).
+
+  flt_otel_scope_span_free
+      Frees a scope span entry if its OTel span has been ended.  Refuses to free
+      an active (non-NULL) span.
+
+  flt_otel_scope_context_init
+      Finds an existing scope context by name or creates a new one by extracting
+      the span context from a text map.
+
+  flt_otel_scope_context_free
+      Frees a scope context entry and destroys the underlying OTel span context.
+
+  flt_otel_scope_data_dump [D]
+      Dumps scope data contents (baggage, attributes, events, links, status) for
+      debugging.
+
+  flt_otel_scope_data_init
+      Zero-initializes a scope data structure and its event/link lists.
+
+  flt_otel_scope_data_free
+      Frees all scope data contents: key-value arrays, event entries, link
+      entries, and status description.
+
+  flt_otel_scope_finish_mark
+      Marks spans and contexts for finishing.  Supports wildcard ("*"),
+      channel-specific ("req"/"res"), and named targets.
+
+  flt_otel_scope_finish_marked
+      Ends all spans and destroys all contexts that have been marked for
+      finishing by flt_otel_scope_finish_mark().
+
+  flt_otel_scope_free_unused
+      Removes scope spans with NULL OTel span and scope contexts with NULL OTel
+      context.  Cleans up associated HTTP headers and variables.
+
+
+src/parser.c
+----------------------------------------------------------------------
+
+Configuration file parsing for otel-instrumentation, otel-group and otel-scope
+sections.
+
+  flt_otel_parse_strdup
+      Duplicates a string with error handling; optionally stores the string
+      length.
+
+  flt_otel_parse_keyword
+      Parses a single keyword argument: checks for duplicates and missing
+      values, then stores via flt_otel_parse_strdup().
+
+  flt_otel_parse_invalid_char
+      Validates characters in a name according to the specified type
+      (identifier, domain, context prefix, variable).
+
+  flt_otel_parse_cfg_check
+      Common validation for config keywords: looks up the keyword, checks
+      argument count and character validity, verifies that the parent section ID
+      is set.
+
+  flt_otel_parse_cfg_sample_expr
+      Parses a single HAProxy sample expression within a sample definition.
+      Calls sample_parse_expr().
+
+  flt_otel_parse_cfg_sample
+      Parses a complete sample definition (key plus one or more sample
+      expressions).
+
+  flt_otel_parse_cfg_str
+      Parses one or more string arguments into a conf_str list (used for the
+      "finish" keyword).
+
+  flt_otel_parse_cfg_file
+      Parses and validates a file path argument; checks that the file exists and
+      is readable.
+
+  flt_otel_parse_check_scope
+      Checks whether the current config parsing is within the correct HAProxy
+      configuration scope (cfg_scope filtering).
+
+  flt_otel_parse_cfg_instr
+      Section parser for the otel-instrumentation block.  Handles keywords:
+      otel-instrumentation ID, log, config, groups, scopes, acl, rate-limit,
+      option, debug-level.
+
+  flt_otel_post_parse_cfg_instr
+      Post-parse callback for otel-instrumentation.  Links the instrumentation
+      to the config and checks that a config file is specified.
+
+  flt_otel_parse_cfg_group
+      Section parser for the otel-group block.  Handles keywords: otel-group ID,
+      scopes.
+
+  flt_otel_post_parse_cfg_group
+      Post-parse callback for otel-group.  Checks that at least one scope is
+      defined.
+
+  flt_otel_parse_cfg_scope_ctx
+      Parses the context storage type argument ("use-headers" or "use-vars") for
+      inject/extract keywords.
+
+  flt_otel_parse_acl
+      Builds an ACL condition by trying multiple ACL lists in order
+      (scope-local, instrumentation, proxy).
+
+  flt_otel_parse_bounds
+      Parses a space-separated string of numbers into a dynamically allocated
+      array of doubles for histogram bucket boundaries.  Sorts the values
+      internally.
+
+  flt_otel_parse_cfg_instrument
+      Parses the "instrument" keyword inside an otel-scope section.  Supports
+      both "update" form (referencing an existing instrument) and "create" form
+      (defining a new metric instrument with type, name, optional aggregation
+      type, description, unit, value, and optional histogram bounds).
+
+  flt_otel_parse_cfg_scope
+      Section parser for the otel-scope block.  Handles keywords: otel-scope ID,
+      span, link, attribute, event, baggage, status, inject, extract, finish,
+      instrument, log-record, acl, otel-event.
+
+  flt_otel_post_parse_cfg_scope
+      Post-parse callback for otel-scope.  Checks that HTTP header injection is
+      only used on events that support it.
+
+  flt_otel_parse_cfg
+      Parses the OTel filter configuration file.  Backs up current sections,
+      registers temporary otel-instrumentation/group/scope section parsers,
+      loads and parses the file, then restores the original sections.
+
+  flt_otel_parse
+      Main filter parser entry point, registered for the "otel" filter keyword.
+      Parses the filter ID and configuration file path from the HAProxy config
+      line.
+
+
+src/conf.c
+----------------------------------------------------------------------
+
+Configuration structure allocation and deallocation.  Most init/free pairs are
+generated by the FLT_OTEL_CONF_FUNC_INIT and FLT_OTEL_CONF_FUNC_FREE macros.
+
+  flt_otel_conf_hdr_init
+      Allocates and initializes a conf_hdr structure.
+
+  flt_otel_conf_hdr_free
+      Frees a conf_hdr structure and removes it from its list.
+
+  flt_otel_conf_str_init
+      Allocates and initializes a conf_str structure.
+
+  flt_otel_conf_str_free
+      Frees a conf_str structure and removes it from its list.
+
+  flt_otel_conf_link_init
+      Allocates and initializes a conf_link structure (span link).
+
+  flt_otel_conf_link_free
+      Frees a conf_link structure and removes it from its list.
+
+  flt_otel_conf_ph_init
+      Allocates and initializes a conf_ph (placeholder) structure.
+
+  flt_otel_conf_ph_free
+      Frees a conf_ph structure and removes it from its list.
+
+  flt_otel_conf_sample_expr_init
+      Allocates and initializes a conf_sample_expr structure.
+
+  flt_otel_conf_sample_expr_free
+      Frees a conf_sample_expr structure and releases the parsed sample
+      expression.
+
+  flt_otel_conf_sample_init
+      Allocates and initializes a conf_sample structure.
+
+  flt_otel_conf_sample_init_ex
+      Extended sample initialization: sets the key, extra data (event name or
+      status code), concatenated value string, and expression count.
+
+  flt_otel_conf_sample_free
+      Frees a conf_sample structure including its value, extra data, and all
+      sample expressions.
+
+  flt_otel_conf_context_init
+      Allocates and initializes a conf_context structure.
+
+  flt_otel_conf_context_free
+      Frees a conf_context structure and removes it from its list.
+
+  flt_otel_conf_span_init
+      Allocates and initializes a conf_span structure with empty lists for
+      links, attributes, events, baggages and statuses.
+
+  flt_otel_conf_span_free
+      Frees a conf_span structure and all its child lists.
+
+  flt_otel_conf_instrument_init
+      Allocates and initializes a conf_instrument structure.
+
+  flt_otel_conf_instrument_free
+      Frees a conf_instrument structure and removes it from its list.
+
+  flt_otel_conf_log_record_init
+      Allocates and initializes a conf_log_record structure with empty
+      attributes and samples lists.
+
+  flt_otel_conf_log_record_free
+      Frees a conf_log_record structure: event_name, span, attributes and
+      samples list.
+
+  flt_otel_conf_scope_init
+      Allocates and initializes a conf_scope structure with empty lists for
+      ACLs, contexts, spans, spans_to_finish and instruments.
+
+  flt_otel_conf_scope_free
+      Frees a conf_scope structure, ACLs, condition, and all child lists.
+
+  flt_otel_conf_group_init
+      Allocates and initializes a conf_group structure with an empty placeholder
+      scope list.
+
+  flt_otel_conf_group_free
+      Frees a conf_group structure and its placeholder scope list.
+
+  flt_otel_conf_instr_init
+      Allocates and initializes a conf_instr structure.  Sets the default rate
+      limit to 100%, initializes the proxy_log, and creates empty ACL and
+      placeholder lists.
+
+  flt_otel_conf_instr_free
+      Frees a conf_instr structure including ACLs, loggers, config path, and
+      placeholder lists.
+
+  flt_otel_conf_init
+      Allocates and initializes the top-level flt_otel_conf structure with empty
+      group and scope lists.
+
+  flt_otel_conf_free
+      Frees the top-level flt_otel_conf structure and all of its children
+      (instrumentation, groups, scopes).
+
+
+src/cli.c
+----------------------------------------------------------------------
+
+HAProxy CLI command handlers for runtime filter management.
+
+  cmn_cli_set_msg
+      Sets the CLI appctx response message and state.
+
+  flt_otel_cli_parse_debug [D]
+      CLI handler for "otel debug [level]".  Gets or sets the debug level.
+
+  flt_otel_cli_parse_disabled
+      CLI handler for "otel enable" and "otel disable".
+
+  flt_otel_cli_parse_option
+      CLI handler for "otel soft-errors" and "otel hard-errors".
+
+  flt_otel_cli_parse_logging
+      CLI handler for "otel logging [state]".  Gets or sets the logging state
+      (off/on/nolognorm).
+
+  flt_otel_cli_parse_rate
+      CLI handler for "otel rate [value]".  Gets or sets the rate limit
+      percentage.
+
+  flt_otel_cli_parse_status
+      CLI handler for "otel status".  Displays filter configuration and runtime
+      state for all OTel filter instances.
+
+  flt_otel_cli_init
+      Registers the OTel CLI keywords with HAProxy.
+
+
+src/otelc.c
+----------------------------------------------------------------------
+
+OpenTelemetry context propagation bridge (inject/extract) between HAProxy and
+the OTel C wrapper library.
+
+  flt_otel_text_map_writer_set_cb
+      Writer callback for text map injection.  Appends a key-value pair to the
+      text map.
+
+  flt_otel_http_headers_writer_set_cb
+      Writer callback for HTTP headers injection.  Appends a key-value pair to
+      the text map.
+
+  flt_otel_inject_text_map
+      Injects span context into a text map carrier.
+
+  flt_otel_inject_http_headers
+      Injects span context into an HTTP headers carrier.
+
+  flt_otel_text_map_reader_foreach_key_cb
+      Reader callback for text map extraction.  Iterates over all key-value
+      pairs in the text map.
+
+  flt_otel_http_headers_reader_foreach_key_cb
+      Reader callback for HTTP headers extraction.  Iterates over all key-value
+      pairs in the text map.
+
+  flt_otel_extract_text_map
+      Extracts a span context from a text map carrier via the tracer.
+
+  flt_otel_extract_http_headers
+      Extracts a span context from an HTTP headers carrier via the tracer.
+
+
+src/http.c
+----------------------------------------------------------------------
+
+HTTP header manipulation for context propagation.
+
+  flt_otel_http_headers_dump [D]
+      Dumps all HTTP headers from the channel's HTX buffer.
+
+  flt_otel_http_headers_get
+      Extracts HTTP headers matching a prefix into a text map.  Used by the
+      "extract" keyword to read span context from incoming request headers.
+
+  flt_otel_http_header_set
+      Sets or removes an HTTP header.  Combines prefix and name into the full
+      header name, removes all existing occurrences, then adds the new value
+      (if non-NULL).
+
+  flt_otel_http_headers_remove
+      Removes all HTTP headers matching a prefix.  Wrapper around
+      flt_otel_http_header_set() with NULL name and value.
+
+
+src/vars.c
+----------------------------------------------------------------------
+
+HAProxy variable integration for context propagation and storage.  Only compiled
+when USE_OTEL_VARS is defined.
+
+  flt_otel_vars_scope_dump [D]
+      Dumps all variables for a single HAProxy variable scope.
+
+  flt_otel_vars_dump [D]
+      Dumps all variables across all scopes (PROC, SESS, TXN, REQ/RES).
+
+  flt_otel_smp_init
+      Initializes a sample structure with stream ownership and optional string
+      data.
+
+  flt_otel_smp_add
+      Appends a context variable name to the binary sample data buffer used for
+      tracking registered context variables.
+
+  flt_otel_normalize_name
+      Normalizes a variable name: replaces dashes with 'D' and spaces with 'S',
+      converts to lowercase.
+
+  flt_otel_denormalize_name
+      Reverses the normalization applied by flt_otel_normalize_name().  Restores
+      dashes from 'D' and spaces from 'S'.
+
+  flt_otel_var_name
+      Constructs a full variable name from scope, prefix and name components,
+      separated by dots.
+
+  flt_otel_ctx_loop
+      Iterates over all context variable names stored in the binary sample data,
+      calling a callback for each.
+
+  flt_otel_ctx_set_cb
+      Callback for flt_otel_ctx_loop() that checks whether a context variable
+      name already exists.
+
+  flt_otel_ctx_set
+      Registers a context variable name in the binary tracking buffer if it is
+      not already present.
+
+  flt_otel_var_register
+      Registers a HAProxy variable via vars_check_arg() so it can be used at
+      runtime.
+
+  flt_otel_var_set
+      Sets a HAProxy variable value.  For context-scope variables, also
+      registers the name in the context tracking buffer.
+
+  flt_otel_vars_unset_cb
+      Callback for flt_otel_ctx_loop() that unsets each context variable.
+
+  flt_otel_vars_unset
+      Unsets all context variables for a given prefix and removes the tracking
+      variable itself.
+
+  flt_otel_vars_get_scope
+      Resolves a scope name string ("proc", "sess", "txn", "req", "res") to the
+      corresponding HAProxy variable store.
+
+  flt_otel_vars_get_cb
+      Callback for flt_otel_ctx_loop() that reads each context variable value
+      and adds it to a text map.
+
+  flt_otel_vars_get
+      Reads all context variables for a prefix into a text map.  Used by the
+      "extract" keyword with variable storage.
+
+
+src/pool.c
+----------------------------------------------------------------------
+
+Memory pool and trash buffer helpers.
+
+  flt_otel_pool_alloc
+      Allocates memory from a HAProxy pool (if available) or from the heap.
+      Optionally zero-fills the allocated block.
+
+  flt_otel_pool_strndup
+      Duplicates a string using a HAProxy pool (if available) or the heap.
+
+  flt_otel_pool_free
+      Returns memory to a HAProxy pool or frees it from the heap.
+
+  flt_otel_trash_alloc
+      Allocates a trash buffer chunk, optionally zero-filled.
+
+  flt_otel_trash_free
+      Frees a trash buffer chunk.
+
+
+src/util.c
+----------------------------------------------------------------------
+
+Utility and conversion functions.
+
+  flt_otel_args_dump [D]
+      Dumps configuration arguments array to stderr.
+
+  flt_otel_filters_dump [D]
+      Dumps all OTel filter instances across all proxies.
+
+  flt_otel_chn_label [D]
+      Returns "REQuest" or "RESponse" based on channel flags.
+
+  flt_otel_pr_mode [D]
+      Returns "HTTP" or "TCP" based on proxy mode.
+
+  flt_otel_stream_pos [D]
+      Returns "frontend" or "backend" based on stream flags.
+
+  flt_otel_type [D]
+      Returns "frontend" or "backend" based on filter flags.
+
+  flt_otel_analyzer [D]
+      Returns the analyzer name string for a given analyzer bit.
+
+  flt_otel_list_dump [D]
+      Returns a summary string for a list (empty, single, count).
+
+  flt_otel_args_count
+      Counts the number of valid (non-NULL) arguments in an args array, handling
+      gaps from blank arguments.
+
+  flt_otel_args_concat
+      Concatenates arguments starting from a given index into a single
+      space-separated string.
+
+  flt_otel_strtod
+      Parses a string to double with range validation.
+
+  flt_otel_strtoll
+      Parses a string to int64 with range validation.
+
+  flt_otel_sample_to_str
+      Converts sample data to its string representation.  Handles bool, sint,
+      IPv4, IPv6, str, and HTTP method types.
+
+  flt_otel_sample_to_value
+      Converts sample data to an otelc_value.  Preserves native types (bool,
+      int64) where possible; falls back to string.
+
+  flt_otel_sample_add_event
+      Adds a sample value as a span event attribute.  Groups attributes by event
+      name; dynamically grows the attribute array.
+
+  flt_otel_sample_set_status
+      Sets the span status code and description from sample data.
+
+  flt_otel_sample_add_kv
+      Adds a sample value as a key-value attribute or baggage entry.
+      Dynamically grows the key-value array.
+
+  flt_otel_sample_eval
+      Evaluates all sample expressions for a configured sample definition and
+      stores the result in an otelc_value.  Supports both log-format and bare
+      sample expression paths.  When flag_native is true and the sample has
+      exactly one expression, the native HAProxy sample type is preserved;
+      otherwise results are concatenated into a string.
+
+  flt_otel_sample_add
+      Top-level sample evaluator and dispatcher.  Calls flt_otel_sample_eval()
+      to evaluate the sample, then dispatches the result to the appropriate
+      handler (attribute, event, baggage, status).
+
+
+src/group.c
+----------------------------------------------------------------------
+
+Group action support for http-response / http-after-response / tcp-request /
+tcp-response rules.
+
+  flt_otel_group_action
+      Action callback (action_ptr) for the otel-group rule.  Finds the filter
+      instance on the current stream and runs all scopes defined in the group.
+
+  flt_otel_group_check
+      Check callback (check_ptr) for the otel-group rule.  Resolves filter ID
+      and group ID references against the proxy's filter configuration.
+
+  flt_otel_group_release
+      Release callback (release_ptr) for the otel-group rule.
+
+  flt_otel_group_parse
+      Parses the "otel-group" action keyword from HAProxy config rules.
+      Registered for tcp-request, tcp-response, http-request, http-response and
+      http-after-response action contexts.

addons/otel/README-misc

@@ -0,0 +1,101 @@
+OpenTelemetry filter -- miscellaneous notes
+==============================================================================
+
+1  Parsing sample expressions in HAProxy
+------------------------------------------------------------------------------
+
+HAProxy provides two entry points for turning a configuration string into an
+evaluable sample expression.
+
+
+1.1  sample_parse_expr()
+..............................................................................
+
+Parses a bare sample-fetch name with an optional converter chain.  The input is
+the raw expression without any surrounding syntax.
+
+  Declared in:  include/haproxy/sample.h
+  Defined in:   src/sample.c
+
+  struct sample_expr *sample_parse_expr(char **str, int *idx, const char *file, int line, char **err_msg, struct arg_list *al, char **endptr);
+
+The function reads from str[*idx] and advances *idx past the consumed tokens.
+
+Configuration example (otel-scope instrument keyword):
+
+  instrument my_counter "name" desc req.hdr(host),lower ...
+
+Here "req.hdr(host),lower" is a single configuration token that
+sample_parse_expr() receives directly.  It recognises the fetch "req.hdr(host)"
+and the converter "lower" separated by a comma.
+
+
+1.2  parse_logformat_string()
+..............................................................................
+
+Parses a log-format string that may contain literal text mixed with sample
+expressions wrapped in %[...] delimiters.
+
+  Declared in:  include/haproxy/log.h
+  Defined in:   src/log.c
+
+  int parse_logformat_string(const char *fmt, struct proxy *curproxy, struct lf_expr *lf_expr, int options, int cap, char **err);
+
+Configuration example (HAProxy log-format directive):
+
+  log-format "host=%[req.hdr(host),lower] status=%[status]"
+
+The %[...] wrapper tells parse_logformat_string() where each embedded sample
+expression begins and ends.  The text outside the brackets ("host=", " status=")
+is emitted as-is.
+
+
+1.3  Which one to use
+..............................................................................
+
+Use sample_parse_expr() when the configuration token is a single, standalone
+sample expression (no surrounding text).  This is the case for the otel filter
+keywords such as "attribute", "event", "baggage", "status", "value", and
+similar.
+
+Use parse_logformat_string() when the value is a free-form string that may mix
+literal text with zero or more embedded expressions.
+
+
+2  Signal keywords
+------------------------------------------------------------------------------
+
+The OTel filter configuration uses one keyword per signal to create or update
+signal-specific objects.  The keyword names follow the OpenTelemetry
+specification's own terminology rather than using informal synonyms.
+
+  Signal      Keyword        Creates / updates
+  --------    -----------    ------------------------------------------
+  Tracing     span           A trace span.
+  Metrics     instrument     A metric instrument (counter, gauge, ...).
+  Logging     log-record     A log record.
+
+The tracing keyword follows the same logic.  A "trace" is the complete
+end-to-end path of a request through a distributed system, composed of one or
+more "spans".  Each span represents a single unit of work within that trace.
+The configuration operates at the span level: it creates individual spans, sets
+their parent-child relationships, and attaches attributes and events.  Using
+"trace" as the keyword would be imprecise because one does not configure a trace
+directly; one configures the spans that collectively form a trace.
+
+The metrics keyword is analogous.  In the OpenTelemetry data model the
+terminology is layered: a "metric" is the aggregated output that the SDK
+produces after processing recorded measurements, while an "instrument" is the
+concrete object through which those measurements are recorded -- a counter,
+histogram, gauge, or up-down counter.  The configuration operates at the
+instrument level: it creates an instrument of a specific type and records values
+through it.  Using "metric" as the keyword would be imprecise because one does
+not configure a metric directly; one configures an instrument that yields
+metrics.
+
+The logging keyword follows the same pattern.  A "log" is the broad signal
+category, while a "log record" is a single discrete entry within that signal.
+The configuration operates at the log-record level: it creates individual log
+records with a severity, a body, and optional attributes and span context.
+Using "log" as the keyword would be imprecise because one does not configure a
+log stream directly; one configures the individual log records that comprise it.

addons/otel/README.md

@@ -0,0 +1,288 @@
+## HAProxy OpenTelemetry Filter (OTel)
+
+The OTel filter enables HAProxy to emit telemetry data -- traces, metrics and
+logs -- to any OpenTelemetry-compatible backend via the OpenTelemetry protocol
+(OTLP).
+
+It is the successor to the OpenTracing (OT) filter, built on the OpenTelemetry
+standard which unifies distributed tracing, metrics and logging into a single
+observability framework.
+
+### Features
+
+- **Distributed tracing** -- spans with parent-child relationships, context
+  propagation via HTTP headers or HAProxy variables, links, baggage and status.
+- **Metrics** -- counter, histogram, up-down counter and gauge instruments with
+  configurable aggregation and bucket boundaries.
+- **Logging** -- log records with severity levels, optional span correlation and
+  runtime-evaluated attributes.
+- **Rate limiting** -- percentage-based sampling (0.0--100.0) for controlling
+  overhead.
+- **ACL integration** -- fine-grained conditional execution at instrumentation,
+  scope and event levels.
+- **CLI management** -- runtime enable/disable, rate adjustment, error mode
+  switching and status inspection.
+- **Context propagation** -- inject/extract span contexts between cascaded
+  HAProxy instances or external services.
+
+### Dependencies
+
+The filter requires the
+[OpenTelemetry C Wrapper](https://github.com/haproxytech/opentelemetry-c-wrapper)
+library, which wraps the OpenTelemetry C++ SDK.
+
+### Building
+
+The OTel filter is compiled together with HAProxy by adding `USE_OTEL=1` to the
+make command.
+
+#### Using pkg-config
+
+```
+PKG_CONFIG_PATH=/opt/lib/pkgconfig make -j8 USE_OTEL=1 TARGET=linux-glibc
+```
+
+#### Explicit paths
+
+```
+make -j8 USE_OTEL=1 OTEL_INC=/opt/include OTEL_LIB=/opt/lib TARGET=linux-glibc
+```
+
+#### Build options
+
+| Variable        | Description                                         |
+|-----------------|-----------------------------------------------------|
+| `USE_OTEL`      | Enable the OpenTelemetry filter                     |
+| `OTEL_DEBUG`    | Compile in debug mode                               |
+| `OTEL_INC`      | Force path to opentelemetry-c-wrapper include files |
+| `OTEL_LIB`      | Force path to opentelemetry-c-wrapper library       |
+| `OTEL_RUNPATH`  | Add opentelemetry-c-wrapper RUNPATH to executable   |
+| `OTEL_USE_VARS` | Enable context propagation via HAProxy variables    |
+
+#### Debug mode
+
+```
+PKG_CONFIG_PATH=/opt/lib/pkgconfig make -j8 USE_OTEL=1 OTEL_DEBUG=1 TARGET=linux-glibc
+```
+
+#### Variable-based context propagation
+
+```
+PKG_CONFIG_PATH=/opt/lib/pkgconfig make -j8 USE_OTEL=1 OTEL_USE_VARS=1 TARGET=linux-glibc
+```
+
+#### Verifying the build
+
+```
+./haproxy -vv | grep -i opentelemetry
+```
+
+If the filter is built in, the output contains:
+
+```
+Built with OpenTelemetry support (C++ version 1.26.0, C Wrapper version 1.0.0-842).
+	[OTEL] opentelemetry
+```
+
+#### Library path at runtime
+
+When pkg-config is not used, the executable may not find the library at startup.
+Use `LD_LIBRARY_PATH` or build with `OTEL_RUNPATH=1`:
+
+```
+LD_LIBRARY_PATH=/opt/lib ./haproxy ...
+```
+
+```
+make -j8 USE_OTEL=1 OTEL_RUNPATH=1 OTEL_INC=/opt/include OTEL_LIB=/opt/lib TARGET=linux-glibc
+```
+
+### Configuration
+
+The filter uses a two-file configuration model:
+
+1. **OTel configuration file** (`.cfg`) -- defines the telemetry model:
+   instrumentation settings, scopes and groups.
+2. **YAML configuration file** (`.yml`) -- defines the OpenTelemetry SDK
+   pipeline: exporters, samplers, processors, providers and signal routing.
+
+#### Activating the filter
+
+The OTel filter requires the `insecure-fork-wanted` keyword in the HAProxy
+`global` section.  This is necessary because the OpenTelemetry C++ SDK creates
+background threads for data export and batch processing.  HAProxy will refuse
+to load the configuration if this keyword is missing.
+
+```
+global
+    insecure-fork-wanted
+    ...
+```
+
+Add the filter to a HAProxy proxy section (frontend/listen/backend):
+
+```
+frontend my-frontend
+    ...
+    filter opentelemetry [id <id>] config <file>
+    ...
+```
+
+If no filter id is specified, `otel-filter` is used as default.
+
+#### OTel configuration file structure
+
+The OTel configuration file contains three section types:
+
+- `otel-instrumentation` -- mandatory; references the YAML file, sets rate
+  limits, error modes, logging and declares groups and scopes.
+- `otel-scope` -- defines actions (spans, attributes, metrics, logs) triggered
+  by stream events or from groups.
+- `otel-group` -- a named collection of scopes triggered from HAProxy TCP/HTTP
+  rules.
+
+#### Minimal YAML configuration
+
+```yaml
+exporters:
+  my_exporter:
+    type:     otlp_http
+    endpoint: "http://localhost:4318/v1/traces"
+
+samplers:
+  my_sampler:
+    type: always_on
+
+processors:
+  my_processor:
+    type: batch
+
+providers:
+  my_provider:
+    resources:
+      - service.name: "haproxy"
+
+signals:
+  traces:
+    scope_name: "HAProxy OTel"
+    exporters:  my_exporter
+    samplers:   my_sampler
+    processors: my_processor
+    providers:  my_provider
+```
+
+#### Supported YAML exporters
+
+| Type            | Description                           |
+|-----------------|---------------------------------------|
+| `otlp_grpc`     | OTLP over gRPC                        |
+| `otlp_http`     | OTLP over HTTP (JSON or Protobuf)     |
+| `otlp_file`     | Local files in OTLP format            |
+| `zipkin`        | Zipkin-compatible backends            |
+| `elasticsearch` | Elasticsearch                         |
+| `ostream`       | Text output to a file (for debugging) |
+| `memory`        | In-memory buffer (for testing)        |
+
+### Scope keywords
+
+| Keyword        | Description                                             |
+|----------------|---------------------------------------------------------|
+| `span`         | Create or reference a span                              |
+| `attribute`    | Set key-value span attributes                           |
+| `event`        | Add timestamped span events                             |
+| `baggage`      | Set context propagation data                            |
+| `status`       | Set span status (ok/error/ignore/unset)                 |
+| `link`         | Add span links to related spans                         |
+| `inject`       | Inject context into headers or variables                |
+| `extract`      | Extract context from headers or variables               |
+| `finish`       | Close spans (supports wildcards: `*`, `*req*`, `*res*`) |
+| `instrument`   | Create or update metric instruments                     |
+| `log-record`   | Emit a log record with severity                         |
+| `otel-event`   | Bind scope to a filter event with optional ACL          |
+| `idle-timeout` | Set periodic event interval for idle streams            |
+
+### CLI commands
+
+Available via the HAProxy CLI socket (prefix: `flt-otel`):
+
+| Command                    | Description                        |
+|----------------------------|------------------------------------|
+| `flt-otel status`          | Show filter status                 |
+| `flt-otel enable`          | Enable the filter                  |
+| `flt-otel disable`         | Disable the filter                 |
+| `flt-otel hard-errors`     | Enable hard-errors mode            |
+| `flt-otel soft-errors`     | Disable hard-errors mode           |
+| `flt-otel logging [state]` | Set logging state                  |
+| `flt-otel rate [value]`    | Set or show the rate limit         |
+| `flt-otel debug [level]`   | Set debug level (debug build only) |
+
+When invoked without arguments, `rate`, `logging` and `debug` display the
+current value.
+
+### Performance
+
+Benchmark results from the standalone (`sa`) configuration, which exercises all
+events (worst-case scenario):
+
+| Rate limit | Req/s  | Avg latency | Overhead |
+|------------|--------|-------------|----------|
+| 100.0%     | 38,202 | 213.08 us   | 21.6%    |
+| 50.0%      | 42,777 | 190.49 us   | 12.2%    |
+| 25.0%      | 45,302 | 180.46 us   | 7.0%     |
+| 10.0%      | 46,879 | 174.69 us   | 3.7%     |
+| 2.5%       | 47,993 | 170.58 us   | 1.4%     |
+| disabled   | 48,788 | 167.74 us   | ~0       |
+| off        | 48,697 | 168.00 us   | baseline |
+
+With a rate limit of 10% or less, the performance impact is negligible.
+Detailed methodology and additional results are in the `test/` directory.
+
+### Test configurations
+
+The `test/` directory contains ready-to-run example configurations:
+
+- **sa** -- standalone; the most comprehensive example, demonstrating spans,
+  attributes, events, links, baggage, status, metrics, log records, ACL
+  conditions and idle-timeout events.
+- **fe/be** -- distributed tracing across two cascaded HAProxy instances using
+  HTTP header-based context propagation.
+- **ctx** -- context propagation via HAProxy variables using the inject/extract
+  mechanism.
+- **cmp** -- minimal configuration for benchmarking comparison.
+- **empty** -- filter initialized with no active telemetry.
+
+#### Quick start with Jaeger
+
+Start a Jaeger all-in-one container:
+
+```
+docker run -d --name jaeger -p 4317:4317 -p 4318:4318 -p 16686:16686 jaegertracing/all-in-one:latest
+```
+
+Run one of the test configurations:
+
+```
+./test/run-sa.sh
+```
+
+Open the Jaeger UI at `http://localhost:16686` to view traces.
+
+### Documentation
+
+Detailed documentation is available in the following files:
+
+- [README](README) -- complete reference documentation
+- [README-configuration](README-configuration) -- configuration guide
+- [README-conf](README-conf) -- configuration details
+- [README-design](README-design) -- cross-cutting design patterns
+- [README-implementation](README-implementation) -- component architecture
+- [README-func](README-func) -- function reference
+- [README-misc](README-misc) -- miscellaneous notes
+
+### Copyright
+
+Copyright 2026 HAProxy Technologies
+
+### Author
+
+Miroslav Zagorac <mzagorac@haproxy.com>

addons/otel/include/cli.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_CLI_H_
+#define _OTEL_CLI_H_
+
+#define FLT_OTEL_CLI_CMD                 "flt-otel"
+
+#define FLT_OTEL_CLI_LOGGING_OFF         "off"
+#define FLT_OTEL_CLI_LOGGING_ON          "on"
+#define FLT_OTEL_CLI_LOGGING_NOLOGNORM   "dontlog-normal"
+#define FLT_OTEL_CLI_LOGGING_STATE(a)    (((a) & FLT_OTEL_LOGGING_ON) ? (((a) & FLT_OTEL_LOGGING_NOLOGNORM) ? "enabled, " FLT_OTEL_CLI_LOGGING_NOLOGNORM : "enabled") : "disabled")
+
+#define FLT_OTEL_CLI_MSG_CAT(a)          (((a) == NULL) ? "" : (a)), (((a) == NULL) ? "" : "\n")
+
+
+/* Register CLI keywords for the OTel filter. */
+void flt_otel_cli_init(void);
+
+#endif /* _OTEL_CLI_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/conf.h

@@ -0,0 +1,313 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_CONF_H_
+#define _OTEL_CONF_H_
+
+/* Extract the OTel filter configuration from a filter instance. */
+#define FLT_OTEL_CONF(f)              ((struct flt_otel_conf *)FLT_CONF(f))
+
+/* Expand to a string pointer and its length for a named member. */
+#define FLT_OTEL_STR_HDR_ARGS(p,m)    (p)->m, (p)->m##_len
+/***
+ * It should be noted that the macro FLT_OTEL_CONF_HDR_ARGS() does not have
+ * all the parameters defined that would correspond to the format found in
+ * the FLT_OTEL_CONF_HDR_FMT macro (first pointer is missing).
+ *
+ * This is because during the expansion of the OTELC_DBG_STRUCT() macro, an
+ * incorrect conversion is performed and instead of the first correct code,
+ * a second incorrect code is generated:
+ *
+ * do {
+ *    if ((p) == NULL)
+ *    ..
+ * } while (0)
+ *
+ * do {
+ *    if ((p), (int) (p)->id_len, (p)->id, (p)->id_len, (p)->cfg_line == NULL)
+ *    ..
+ * } while (0)
+ *
+ */
+#define FLT_OTEL_CONF_HDR_FMT         "%p:{ { '%.*s' %zu %d } "
+#define FLT_OTEL_CONF_HDR_ARGS(p,m)   (int)(p)->m##_len, (p)->m, (p)->m##_len, (p)->cfg_line
+
+/*
+ * Special two-byte prefix that triggers automatic id generation in
+ * FLT_OTEL_CONF_FUNC_INIT(): the text after the prefix is combined
+ * with the configuration line number to form a unique identifier.
+ */
+#define FLT_OTEL_CONF_HDR_SPECIAL     "\x1e\x1f"
+
+#define FLT_OTEL_CONF_STR_CMP(s,S)    ((s##_len == S##_len) && (memcmp(s, S, S##_len) == 0))
+
+#define FLT_OTEL_DBG_CONF_SAMPLE_EXPR(h,p) \
+	OTELC_DBG(DEBUG, h "%p:{ '%s' %p }", (p), (p)->fmt_expr, (p)->expr)
+
+#define FLT_OTEL_DBG_CONF_SAMPLE(h,p)                                             \
+	OTELC_DBG(DEBUG, h "%p:{ '%s' '%s' %s %s %d %p %hhu }", (p),              \
+	          (p)->key, (p)->fmt_string, otelc_value_dump(&((p)->extra), ""), \
+	          flt_otel_list_dump(&((p)->exprs)), (p)->num_exprs, &((p)->lf_expr), (p)->lf_used)
+
+#define FLT_OTEL_DBG_CONF_HDR(h,p,i) \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "}", (p), FLT_OTEL_CONF_HDR_ARGS(p, i))
+
+#define FLT_OTEL_DBG_CONF_CONTEXT(h,p) \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "0x%02hhx }", (p), FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->flags)
+
+#define FLT_OTEL_DBG_CONF_SPAN(h,p)                                                                           \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "'%s' %zu %s' %zu %hhu 0x%02hhx %s %s %s %s %s }", \
+	                 (p), FLT_OTEL_CONF_HDR_ARGS(p, id), FLT_OTEL_STR_HDR_ARGS(p, ref_id),                \
+	                 FLT_OTEL_STR_HDR_ARGS(p, ctx_id), (p)->flag_root, (p)->ctx_flags,                    \
+	                 flt_otel_list_dump(&((p)->links)), flt_otel_list_dump(&((p)->attributes)),           \
+	                 flt_otel_list_dump(&((p)->events)), flt_otel_list_dump(&((p)->baggages)),            \
+	                 flt_otel_list_dump(&((p)->statuses)))
+
+#define FLT_OTEL_DBG_CONF_SCOPE(h,p)                                                                        \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "%hhu %d %u %s %p %s %s %s %s %s }", (p),        \
+	                 FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->flag_used, (p)->event, (p)->idle_timeout,      \
+	                 flt_otel_list_dump(&((p)->acls)), (p)->cond, flt_otel_list_dump(&((p)->contexts)), \
+	                 flt_otel_list_dump(&((p)->spans)), flt_otel_list_dump(&((p)->spans_to_finish)),    \
+	                 flt_otel_list_dump(&((p)->instruments)), flt_otel_list_dump(&((p)->log_records)))
+
+#define FLT_OTEL_DBG_CONF_GROUP(h,p)                                         \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "%hhu %s }", (p), \
+	                 FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->flag_used, flt_otel_list_dump(&((p)->ph_scopes)))
+
+#define FLT_OTEL_DBG_CONF_PH(h,p) \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "%p }", (p), FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->ptr)
+
+#define FLT_OTEL_DBG_CONF_INSTR(h,p)                                                                                         \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "'%s' %p %p %p %u %hhu %hhu 0x%02hhx %p:%s 0x%08x %u %s %s %s }", \
+	                 (p), FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->config, (p)->tracer, (p)->meter, (p)->logger,              \
+	                 (p)->rate_limit, (p)->flag_harderr, (p)->flag_disabled, (p)->logging, &((p)->proxy_log),            \
+	                 flt_otel_list_dump(&((p)->proxy_log.loggers)), (p)->analyzers, (p)->idle_timeout,                   \
+	                 flt_otel_list_dump(&((p)->acls)), flt_otel_list_dump(&((p)->ph_groups)),                            \
+	                 flt_otel_list_dump(&((p)->ph_scopes)))
+
+#define FLT_OTEL_DBG_CONF_INSTRUMENT(h,p)                                                                                     \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "%" PRId64 " %d %d '%s' '%s' %s %s %p %zu %p }", (p),              \
+	                 FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->idx, (p)->type, (p)->aggr_type, OTELC_STR_ARG((p)->description), \
+	                 OTELC_STR_ARG((p)->unit), flt_otel_list_dump(&((p)->samples)), flt_otel_list_dump(&((p)->attributes)), \
+	                 (p)->ref, (p)->bounds_num, (p)->bounds)
+
+#define FLT_OTEL_DBG_CONF_LOG_RECORD(h,p)                                                                             \
+	OTELC_DBG_STRUCT(DEBUG, h, h FLT_OTEL_CONF_HDR_FMT "%d %" PRId64 " '%s' '%s' %s %s }", (p),                  \
+	                 FLT_OTEL_CONF_HDR_ARGS(p, id), (p)->severity, (p)->event_id, OTELC_STR_ARG((p)->event_name), \
+	                 OTELC_STR_ARG((p)->span), flt_otel_list_dump(&((p)->attributes)), flt_otel_list_dump(&((p)->samples)))
+
+#define FLT_OTEL_DBG_CONF(h,p)                                    \
+	OTELC_DBG(DEBUG, h "%p:{ %p '%s' '%s' %p %s %s }", (p),   \
+	          (p)->proxy, (p)->id, (p)->cfg_file, (p)->instr, \
+	          flt_otel_list_dump(&((p)->groups)), flt_otel_list_dump(&((p)->scopes)))
+
+/* Anonymous struct containing a string pointer and its length. */
+#define FLT_OTEL_CONF_STR(p)     \
+	struct {                 \
+		char   *p;       \
+		size_t  p##_len; \
+	}
+
+/* Common header embedded in all configuration structures. */
+#define FLT_OTEL_CONF_HDR(p)          \
+	struct {                      \
+		FLT_OTEL_CONF_STR(p); \
+		int         cfg_line; \
+		struct list list;     \
+	}
+
+
+/* Generic configuration header used for simple named list entries. */
+struct flt_otel_conf_hdr {
+	FLT_OTEL_CONF_HDR(id); /* A list containing header names. */
+};
+
+/* flt_otel_conf_sample->exprs */
+struct flt_otel_conf_sample_expr {
+	FLT_OTEL_CONF_HDR(fmt_expr); /* The original sample expression format string. */
+	struct sample_expr *expr;    /* The sample expression. */
+};
+
+/*
+ * flt_otel_conf_span->attributes
+ * flt_otel_conf_span->events (event_name -> OTELC_VALUE_STR(&extra))
+ * flt_otel_conf_span->baggages
+ * flt_otel_conf_span->statuses (status_code -> extra.u.value_int32)
+ * flt_otel_conf_instrument->samples
+ * flt_otel_conf_log_record->samples
+ */
+struct flt_otel_conf_sample {
+	FLT_OTEL_CONF_HDR(key);         /* The list containing sample names. */
+	char               *fmt_string; /* All sample-expression arguments are combined into a single string. */
+	struct otelc_value  extra;      /* Optional supplementary data. */
+	struct list         exprs;      /* Used to chain sample expressions. */
+	int                 num_exprs;  /* Number of defined expressions. */
+	struct lf_expr      lf_expr;    /* The log-format expression. */
+	bool                lf_used;    /* Whether lf_expr is used instead of exprs. */
+};
+
+/*
+ * flt_otel_conf_scope->spans_to_finish
+ *
+ * It can be seen that this structure is actually identical to the structure
+ * flt_otel_conf_hdr.
+ */
+struct flt_otel_conf_str {
+	FLT_OTEL_CONF_HDR(str); /* A list containing character strings. */
+};
+
+/* flt_otel_conf_scope->contexts */
+struct flt_otel_conf_context {
+	FLT_OTEL_CONF_HDR(id); /* The name of the context. */
+	uint8_t flags;         /* The type of storage from which the span context is extracted.  */
+};
+
+/* flt_otel_conf_span->links */
+struct flt_otel_conf_link {
+	FLT_OTEL_CONF_HDR(span); /* The list containing link names. */
+};
+
+/*
+ * Span configuration within a scope.
+ *   flt_otel_conf_scope->spans
+ */
+struct flt_otel_conf_span {
+	FLT_OTEL_CONF_HDR(id);     /* The name of the span. */
+	FLT_OTEL_CONF_STR(ref_id); /* The reference name, if used. */
+	FLT_OTEL_CONF_STR(ctx_id); /* The span context name, if used. */
+	uint8_t     ctx_flags;     /* The type of storage used for the span context. */
+	bool        flag_root;     /* Whether this is a root span. */
+	struct list links;         /* The set of linked span names. */
+	struct list attributes;    /* The set of key:value attributes. */
+	struct list events;        /* The set of events with key-value attributes. */
+	struct list baggages;      /* The set of key:value baggage items. */
+	struct list statuses;      /* Span status code and description (only one per list). */
+};
+
+/*
+ * Metric instrument configuration within a scope.
+ *   flt_otel_conf_scope->instruments
+ */
+struct flt_otel_conf_instrument {
+	FLT_OTEL_CONF_HDR(id);                          /* The name of the instrument. */
+	int64_t                            idx;         /* Meter instrument index (-1 if not yet created). */
+	otelc_metric_instrument_t          type;        /* Instrument type (or UPDATE). */
+	otelc_metric_aggregation_type_t    aggr_type;   /* Aggregation type for the view (create only). */
+	char                              *description; /* Instrument description (create only). */
+	char                              *unit;        /* Instrument unit (create only). */
+	struct list                        samples;     /* Sample expressions for the value. */
+	double                            *bounds;      /* Histogram bucket boundaries (create only). */
+	size_t                             bounds_num;  /* Number of histogram bucket boundaries. */
+	struct list                        attributes;  /* Instrument attributes (update only, flt_otel_conf_sample). */
+	struct flt_otel_conf_instrument   *ref;         /* Resolved create-form instrument (update only). */
+};
+
+/*
+ * Log record configuration within a scope.
+ *   flt_otel_conf_scope->log_records
+ */
+struct flt_otel_conf_log_record {
+	FLT_OTEL_CONF_HDR(id);            /* Required by macro; member <id> is not used directly. */
+	otelc_log_severity_t  severity;   /* The severity level. */
+	int64_t               event_id;   /* Optional event identifier. */
+	char                 *event_name; /* Optional event name. */
+	char                 *span;       /* Optional span reference. */
+	struct list           attributes; /* Log record attributes (flt_otel_conf_sample). */
+	struct list           samples;    /* Sample expressions for the body. */
+};
+
+/* Configuration for a single event scope. */
+struct flt_otel_conf_scope {
+	FLT_OTEL_CONF_HDR(id);            /* The scope name. */
+	bool             flag_used;       /* The indication that the scope is being used. */
+	int              event;           /* FLT_OTEL_EVENT_* */
+	uint             idle_timeout;    /* Idle timeout interval in milliseconds (0 = off). */
+	struct list      acls;            /* ACLs declared on this scope. */
+	struct acl_cond *cond;            /* ACL condition to meet. */
+	struct list      contexts;        /* Declared contexts. */
+	struct list      spans;           /* Declared spans. */
+	struct list      spans_to_finish; /* The list of spans scheduled for finishing. */
+	struct list      instruments;     /* The list of metric instruments. */
+	struct list      log_records;     /* The list of log records. */
+};
+
+/* Configuration for a named group of scopes. */
+struct flt_otel_conf_group {
+	FLT_OTEL_CONF_HDR(id); /* The group name. */
+	bool        flag_used; /* The indication that the group is being used. */
+	struct list ph_scopes; /* List of all used scopes. */
+};
+
+/* Placeholder referencing a scope or group by name. */
+struct flt_otel_conf_ph {
+	FLT_OTEL_CONF_HDR(id); /* The scope/group name. */
+	void *ptr;             /* Pointer to real placeholder structure. */
+};
+#define flt_otel_conf_ph_group        flt_otel_conf_ph
+#define flt_otel_conf_ph_scope        flt_otel_conf_ph
+
+/* Top-level OTel instrumentation settings (tracer, meter, options). */
+struct flt_otel_conf_instr {
+	FLT_OTEL_CONF_HDR(id);              /* The OpenTelemetry instrumentation name. */
+	char                *config;        /* The OpenTelemetry configuration file name. */
+	struct otelc_tracer *tracer;        /* The OpenTelemetry tracer handle. */
+	struct otelc_meter  *meter;         /* The OpenTelemetry meter handle. */
+	struct otelc_logger *logger;        /* The OpenTelemetry logger handle. */
+	uint32_t             rate_limit;    /* [0 2^32-1] <-> [0.0 100.0] */
+	bool                 flag_harderr;  /* [0 1] */
+	bool                 flag_disabled; /* [0 1] */
+	uint8_t              logging;       /* [0 1 3] */
+	struct proxy         proxy_log;     /* The log server list. */
+	uint                 analyzers;     /* Defined channel analyzers. */
+	uint                 idle_timeout;  /* Minimum idle timeout across scopes (ms, 0 = off). */
+	struct list          acls;          /* ACLs declared on this tracer. */
+	struct list          ph_groups;     /* List of all used groups. */
+	struct list          ph_scopes;     /* List of all used scopes. */
+};
+
+/* Runtime counters for filter diagnostics. */
+struct flt_otel_counters {
+#ifdef DEBUG_OTEL
+	struct {
+		bool     flag_used; /* Whether this event is used. */
+		uint64_t htx[2];    /* htx_is_empty() function result counter. */
+	} event[FLT_OTEL_EVENT_MAX];
+#endif
+
+#ifdef FLT_OTEL_USE_COUNTERS
+	uint64_t attached[4];       /* [run rate-limit disabled error] */
+	uint64_t disabled[2];       /* How many times stream processing is disabled. */
+#endif
+};
+
+/* The OpenTelemetry filter configuration. */
+struct flt_otel_conf {
+	struct proxy               *proxy;    /* Proxy owning the filter. */
+	char                       *id;       /* The OpenTelemetry filter id. */
+	char                       *cfg_file; /* The OpenTelemetry filter configuration file name. */
+	struct flt_otel_conf_instr *instr;    /* The OpenTelemetry instrumentation settings. */
+	struct list                 groups;   /* List of all available groups. */
+	struct list                 scopes;   /* List of all available scopes. */
+	struct flt_otel_counters    cnt;      /* Various counters related to filter operation. */
+	struct list                 smp_args; /* Deferred OTEL sample fetch args to resolve. */
+};
+
+
+/* Allocate and initialize a sample from parsed arguments. */
+struct flt_otel_conf_sample *flt_otel_conf_sample_init_ex(const char **args, int idx, int n, const struct otelc_value *extra, int line, struct list *head, char **err);
+
+/* Allocate and initialize the top-level OTel filter configuration. */
+struct flt_otel_conf        *flt_otel_conf_init(struct proxy *px);
+
+/* Free the top-level OTel filter configuration. */
+void                         flt_otel_conf_free(struct flt_otel_conf **ptr);
+
+#endif /* _OTEL_CONF_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/conf_funcs.h

@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_CONF_FUNCS_H_
+#define _OTEL_CONF_FUNCS_H_
+
+/*
+ * Macro that generates a flt_otel_conf_<type>_init() function.  The generated
+ * function allocates and initializes a configuration structure of the given
+ * type, checks for duplicate names in the list, and optionally runs a custom
+ * initializer body.
+ */
+#define FLT_OTEL_CONF_FUNC_INIT(_type_, _id_, _func_)                                                                         \
+	struct flt_otel_conf_##_type_ *flt_otel_conf_##_type_##_init(const char *id, int line, struct list *head, char **err) \
+	{                                                                                                                     \
+		struct flt_otel_conf_##_type_ *retptr = NULL;                                                                 \
+		struct flt_otel_conf_##_type_ *ptr;                                                                           \
+		char                           id_buffer[FLT_OTEL_ID_MAXLEN + 16];                                            \
+		size_t                         _id_##_len;                                                                    \
+		                                                                                                              \
+		OTELC_FUNC("\"%s\", %d, %p, %p:%p", OTELC_STR_ARG(id), line, head, OTELC_DPTR_ARGS(err));                     \
+		                                                                                                              \
+		if ((id == NULL) || (*id == '\0')) {                                                                          \
+			FLT_OTEL_ERR("name not set");                                                                         \
+		                                                                                                              \
+			OTELC_RETURN_PTR(retptr);                                                                             \
+		}                                                                                                             \
+		else if ((id[0] == FLT_OTEL_CONF_HDR_SPECIAL[0]) && (id[1] == FLT_OTEL_CONF_HDR_SPECIAL[1])) {                \
+			(void)snprintf(id_buffer, sizeof(id_buffer), "%s:%d", id + 2, line);                                  \
+		                                                                                                              \
+			id = id_buffer;                                                                                       \
+		}                                                                                                             \
+		                                                                                                              \
+		_id_##_len = strlen(id);                                                                                      \
+		if (_id_##_len >= FLT_OTEL_ID_MAXLEN) {                                                                       \
+			FLT_OTEL_ERR("'%s' : name too long", id);                                                             \
+		                                                                                                              \
+			OTELC_RETURN_PTR(retptr);                                                                             \
+		}                                                                                                             \
+		                                                                                                              \
+		if (head != NULL)                                                                                             \
+			list_for_each_entry(ptr, head, list)                                                                  \
+				if (strcmp(ptr->_id_, id) == 0) {                                                             \
+					FLT_OTEL_ERR("'%s' : already defined", id);                                           \
+		                                                                                                              \
+					OTELC_RETURN_PTR(retptr);                                                             \
+				}                                                                                             \
+		                                                                                                              \
+		retptr = OTELC_CALLOC(1, sizeof(*retptr));                                                                    \
+		if (retptr != NULL) {                                                                                         \
+			retptr->cfg_line   = line;                                                                            \
+			retptr->_id_##_len = _id_##_len;                                                                      \
+			retptr->_id_       = OTELC_STRDUP(id);                                                                \
+			if (retptr->_id_ != NULL) {                                                                           \
+				if (head != NULL)                                                                             \
+					LIST_APPEND(head, &(retptr->list));                                                   \
+		                                                                                                              \
+				FLT_OTEL_DBG_CONF_HDR("- conf_" #_type_ " init ", retptr, _id_);                              \
+			}                                                                                                     \
+			else                                                                                                  \
+				OTELC_SFREE_CLEAR(retptr);                                                                    \
+		}                                                                                                             \
+		                                                                                                              \
+		if (retptr != NULL) {                                                                                         \
+			_func_                                                                                                \
+		}                                                                                                             \
+		                                                                                                              \
+		if (retptr == NULL)                                                                                           \
+			FLT_OTEL_ERR("out of memory");                                                                        \
+		                                                                                                              \
+		OTELC_RETURN_PTR(retptr);                                                                                     \
+	}
+
+/*
+ * Macro that generates a flt_otel_conf_<type>_free() function.  The generated
+ * function runs a custom cleanup body, then frees the name string, removes the
+ * structure from its list, and frees the structure.
+ */
+#define FLT_OTEL_CONF_FUNC_FREE(_type_, _id_, _func_)                           \
+	void flt_otel_conf_##_type_##_free(struct flt_otel_conf_##_type_ **ptr) \
+	{                                                                       \
+		OTELC_FUNC("%p:%p", OTELC_DPTR_ARGS(ptr));                      \
+		                                                                \
+		if ((ptr == NULL) || (*ptr == NULL))                            \
+			OTELC_RETURN();                                         \
+		                                                                \
+		{ _func_ }                                                      \
+		                                                                \
+		OTELC_SFREE((*ptr)->_id_);                                      \
+		FLT_OTEL_LIST_DEL(&((*ptr)->list));                             \
+		OTELC_SFREE_CLEAR(*ptr);                                        \
+		                                                                \
+		OTELC_RETURN();                                                 \
+	}
+
+
+/* The FLT_OTEL_LIST_DESTROY() macro uses the following two definitions. */
+#define flt_otel_conf_ph_group_free    flt_otel_conf_ph_free
+#define flt_otel_conf_ph_scope_free    flt_otel_conf_ph_free
+
+/* Declare init/free function prototypes for a configuration type. */
+#define FLT_OTEL_CONF_FUNC_DECL(_type_)                                                                                        \
+	struct flt_otel_conf_##_type_ *flt_otel_conf_##_type_##_init(const char *id, int line, struct list *head, char **err); \
+	void                           flt_otel_conf_##_type_##_free(struct flt_otel_conf_##_type_ **ptr);
+
+FLT_OTEL_CONF_FUNC_DECL(hdr)
+FLT_OTEL_CONF_FUNC_DECL(str)
+FLT_OTEL_CONF_FUNC_DECL(ph)
+FLT_OTEL_CONF_FUNC_DECL(sample_expr)
+FLT_OTEL_CONF_FUNC_DECL(sample)
+FLT_OTEL_CONF_FUNC_DECL(link)
+FLT_OTEL_CONF_FUNC_DECL(context)
+FLT_OTEL_CONF_FUNC_DECL(span)
+FLT_OTEL_CONF_FUNC_DECL(scope)
+FLT_OTEL_CONF_FUNC_DECL(instrument)
+FLT_OTEL_CONF_FUNC_DECL(log_record)
+FLT_OTEL_CONF_FUNC_DECL(group)
+FLT_OTEL_CONF_FUNC_DECL(instr)
+
+#endif /* _OTEL_CONF_FUNCS_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/config.h

@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_CONFIG_H_
+#define _OTEL_CONFIG_H_
+
+/* Memory pool selection flags. */
+#define USE_POOL_BUFFER
+#define USE_POOL_OTEL_SPAN_CONTEXT
+#define USE_POOL_OTEL_SCOPE_SPAN
+#define USE_POOL_OTEL_SCOPE_CONTEXT
+#define USE_POOL_OTEL_RUNTIME_CONTEXT
+#define USE_TRASH_CHUNK
+
+/* Enable per-event and per-stream diagnostic counters in debug builds. */
+#if defined(DEBUG_OTEL) && !defined(FLT_OTEL_USE_COUNTERS)
+#  define FLT_OTEL_USE_COUNTERS
+#endif
+
+#define FLT_OTEL_ID_MAXLEN        64            /* Maximum identifier length. */
+#define FLT_OTEL_DEBUG_LEVEL   0b11101111111 /* Default debug bitmask. */
+
+#define FLT_OTEL_ATTR_INIT_SIZE   8 /* Initial attribute array capacity. */
+#define FLT_OTEL_ATTR_INC_SIZE    4 /* Attribute array growth increment. */
+
+#endif /* _OTEL_CONFIG_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/debug.h

@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_DEBUG_H_
+#define _OTEL_DEBUG_H_
+
+#ifdef DEBUG_FULL
+#  define DEBUG_OTEL
+#endif
+
+/*
+ * FLT_OTEL_DBG_ARGS - include extra debug-only function parameters.
+ * FLT_OTEL_DBG_BUF  - dump a buffer structure for debugging.
+ *
+ * When DEBUG_OTEL is not defined, these expand to nothing.
+ */
+#ifdef DEBUG_OTEL
+#  define FLT_OTEL_DBG_ARGS(a, ...)   a, ##__VA_ARGS__
+#  define FLT_OTEL_DBG_BUF(l,a)       OTELC_DBG(l, "%p:{ %zu %p %zu %zu }", (a), (a)->size, (a)->area, (a)->data, (a)->head)
+#else
+#  define FLT_OTEL_DBG_ARGS(...)
+#  define FLT_OTEL_DBG_BUF(...)       while (0)
+#endif /* DEBUG_OTEL */
+
+/*
+ *  ON  | NOLOGNORM |
+ * -----+-----------+-------------
+ *   0  |     0     |  no log
+ *   0  |     1     |  no log
+ *   1  |     0     |  log all
+ *   1  |     1     |  log errors
+ * -----+-----------+-------------
+ */
+#define FLT_OTEL_LOG(l,f, ...)                                                                                                   \
+	do {                                                                                                                     \
+		if (!(conf->instr->logging & FLT_OTEL_LOGGING_ON))                                                               \
+			OTELC_DBG(DEBUG, "NOLOG[%d]: [" FLT_OTEL_SCOPE "]: [%s] " f, (l), conf->id, ##__VA_ARGS__);              \
+		else if ((conf->instr->logging & FLT_OTEL_LOGGING_NOLOGNORM) && ((l) > LOG_ERR))                                 \
+			OTELC_DBG(NOTICE, "NOLOG[%d]: [" FLT_OTEL_SCOPE "]: [%s] " f, (l), conf->id, ##__VA_ARGS__);             \
+		else {                                                                                                           \
+			send_log(&(conf->instr->proxy_log), (l), "[" FLT_OTEL_SCOPE "]: [%s] " f "\n", conf->id, ##__VA_ARGS__); \
+			                                                                                                         \
+			OTELC_DBG(INFO, "LOG[%d]: %s", (l), logline);                                                            \
+		}                                                                                                                \
+	} while (0)
+
+#endif /* _OTEL_DEBUG_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/define.h

@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_DEFINE_H_
+#define _OTEL_DEFINE_H_
+
+/* Safe pointer dereference with default value. */
+#define FLT_OTEL_DEREF(p,m,v)        (((p) != NULL) ? (p)->m : (v))
+
+/* Check whether argument at index n is in range, non-NULL and non-empty. */
+#define FLT_OTEL_ARG_ISVALID(n)      ({ typeof(n) _n = (n); OTELC_IN_RANGE(_n, 0, MAX_LINE_ARGS - 1) && (args[_n] != NULL) && (*args[_n] != '\0'); })
+
+/* Convert a uint32_t rate value to a floating-point percentage. */
+#define FLT_OTEL_U32_FLOAT(a)        ((a) * 100.0 / UINT32_MAX)
+
+/* Convert a floating-point percentage to a uint32_t rate value. */
+#define FLT_OTEL_FLOAT_U32(a)        ((uint32_t)((a) / 100.0 * UINT32_MAX + 0.5))
+
+#define FLT_OTEL_STR_DASH_72         "------------------------------------------------------------------------"
+#define FLT_OTEL_STR_DASH_78         FLT_OTEL_STR_DASH_72 "------"
+#define FLT_OTEL_STR_FLAG_YN(a)      ((a) ? "yes" : "no")
+
+/* Compile-time string length excluding the null terminator. */
+#define FLT_OTEL_STR_SIZE(a)         (sizeof(a) - 1)
+
+/* Expand to address and length pair for a string literal. */
+#define FLT_OTEL_STR_ADDRSIZE(a)     (a), FLT_OTEL_STR_SIZE(a)
+
+/* Compare a runtime string against a compile-time string literal. */
+#define FLT_OTEL_STR_CMP(S,s)        ((s##_len == FLT_OTEL_STR_SIZE(S)) && (memcmp((s), FLT_OTEL_STR_ADDRSIZE(S)) == 0))
+
+/* Tolerance for double comparison in flt_otel_qsort_compar_double(). */
+#define FLT_OTEL_DBL_EPSILON         1e-9
+
+/* Execute a statement exactly once across all invocations. */
+#define FLT_OTEL_RUN_ONCE(f)         do { static bool _f = 1; if (_f) { _f = 0; { f; } } } while (0)
+
+/* Check whether a list head has been initialized. */
+#define FLT_OTEL_LIST_ISVALID(a)     ({ typeof(a) _a = (a); (_a != NULL) && (_a->n != NULL) && (_a->p != NULL); })
+
+/* Safely delete a list element if its list head is valid. */
+#define FLT_OTEL_LIST_DEL(a)         do { if (FLT_OTEL_LIST_ISVALID(a)) LIST_DELETE(a); } while (0)
+
+/* Destroy all elements in a typed configuration list. */
+#define FLT_OTEL_LIST_DESTROY(t,h)                                                     \
+	do {                                                                           \
+		struct flt_otel_conf_##t *_ptr, *_back;                                \
+		                                                                       \
+		if (!FLT_OTEL_LIST_ISVALID(h) || LIST_ISEMPTY(h))                      \
+			break;                                                         \
+		                                                                       \
+		OTELC_DBG(NOTICE, "- deleting " #t " list %s", flt_otel_list_dump(h)); \
+		                                                                       \
+		list_for_each_entry_safe(_ptr, _back, (h), list)                       \
+			flt_otel_conf_##t##_free(&_ptr);                               \
+	} while (0)
+
+/* Declare a rotating thread-local string buffer pool. */
+#define FLT_OTEL_BUFFER_THR(b,m,n,p)              \
+	static THREAD_LOCAL char    b[m][n];      \
+	static THREAD_LOCAL size_t  __idx = 0;    \
+	char                       *p = b[__idx]; \
+	__idx = (__idx + 1) % (m)
+
+/* Format an error message if none has been set yet. */
+#define FLT_OTEL_ERR(f, ...)                                    \
+	do {                                                    \
+		if ((err != NULL) && (*err == NULL)) {          \
+			(void)memprintf(err, f, ##__VA_ARGS__); \
+		                                                \
+			OTELC_DBG(DEBUG, "err: '%s'", *err);    \
+		}                                               \
+	} while (0)
+/* Append to an existing error message unconditionally. */
+#define FLT_OTEL_ERR_APPEND(f, ...)                             \
+	do {                                                    \
+		if (err != NULL)                                \
+			(void)memprintf(err, f, ##__VA_ARGS__); \
+	} while (0)
+/* Log an error message and free its memory. */
+#define FLT_OTEL_ERR_FREE(p)                                                 \
+	do {                                                                 \
+		if ((p) == NULL)                                             \
+			break;                                               \
+		                                                             \
+		OTELC_DBG(LOG, "%s:%d: ERROR: %s", __func__, __LINE__, (p)); \
+		OTELC_SFREE_CLEAR(p);                                        \
+	} while (0)
+
+#endif /* _OTEL_DEFINE_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/event.h

@@ -0,0 +1,152 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_EVENT_H_
+#define _OTEL_EVENT_H_
+
+/*
+ * This must be defined in order for macro FLT_OTEL_EVENT_DEFINES
+ * and structure flt_otel_event_data to have the correct contents.
+ */
+#define AN__NONE                    0
+#define AN__STREAM_START            0     /* on-stream-start */
+#define AN__STREAM_STOP             0     /* on-stream-stop */
+#define AN__IDLE_TIMEOUT            0     /* on-idle-timeout */
+#define AN__BACKEND_SET             0     /* on-backend-set */
+#define AN_REQ_HTTP_HEADERS         0     /* on-http-headers-request */
+#define AN_RES_HTTP_HEADERS         0     /* on-http-headers-response */
+#define AN_REQ_HTTP_END             0     /* on-http-end-request */
+#define AN_RES_HTTP_END             0     /* on-http-end-response */
+#define AN_RES_HTTP_REPLY           0     /* on-http-reply */
+#define AN_REQ_CLIENT_SESS_START    0
+#define AN_REQ_SERVER_UNAVAILABLE   0
+#define AN_REQ_CLIENT_SESS_END      0
+#define AN_RES_SERVER_SESS_START    0
+#define AN_RES_SERVER_SESS_END      0
+#define SMP_VAL_FE_                 0
+#define SMP_VAL_BE_                 0
+#define SMP_OPT_DIR_                0xff
+
+/*
+ * Event names are selected to be somewhat compatible with the SPOE filter,
+ * from which the following names are taken:
+ *   - on-client-session -> on-client-session-start
+ *   - on-frontend-tcp-request
+ *   - on-frontend-http-request
+ *   - on-backend-tcp-request
+ *   - on-backend-http-request
+ *   - on-server-session -> on-server-session-start
+ *   - on-tcp-response
+ *   - on-http-response
+ *
+ * FLT_OTEL_EVENT_NONE is used as an index for 'otel-scope' sections that do not
+ * have an event defined.  The 'otel-scope' sections thus defined can be used
+ * within the 'otel-group' section.
+ *
+ * A description of the macro arguments can be found in the structure
+ * flt_otel_event_data definition.
+ *
+ * The following table is derived from the definitions AN_REQ_* and AN_RES_*
+ * found in the HAProxy include file include/haproxy/channel-t.h.
+ */
+#define FLT_OTEL_EVENT_DEFINES                                                                                \
+	/* Stream lifecycle pseudo-events (an_bit = 0, not tied to a channel analyzer) */                     \
+	FLT_OTEL_EVENT_DEF(              NONE,    ,        ,        , 0, "")                                  \
+	FLT_OTEL_EVENT_DEF(      STREAM_START,    ,        ,        , 0, "on-stream-start")                   \
+	FLT_OTEL_EVENT_DEF(       STREAM_STOP,    ,        ,        , 0, "on-stream-stop")                    \
+	FLT_OTEL_EVENT_DEF( CLIENT_SESS_START, REQ, CON_ACC,        , 1, "on-client-session-start")           \
+	FLT_OTEL_EVENT_DEF(      IDLE_TIMEOUT,    ,        ,        , 0, "on-idle-timeout")                   \
+	FLT_OTEL_EVENT_DEF(       BACKEND_SET,    ,        ,        , 0, "on-backend-set")                    \
+	                                                                                                      \
+	/* Request analyzers */                                                                               \
+/*	FLT_OTEL_EVENT_DEF(      FLT_START_FE, REQ,        ,        ,  , "on-filter-start") */                \
+	FLT_OTEL_EVENT_DEF(        INSPECT_FE, REQ, REQ_CNT,        , 1, "on-frontend-tcp-request")           \
+	FLT_OTEL_EVENT_DEF(         WAIT_HTTP, REQ,        ,        , 1, "on-http-wait-request")              \
+	FLT_OTEL_EVENT_DEF(         HTTP_BODY, REQ,        ,        , 1, "on-http-body-request")              \
+	FLT_OTEL_EVENT_DEF(   HTTP_PROCESS_FE, REQ, HRQ_HDR,        , 1, "on-frontend-http-request")          \
+	FLT_OTEL_EVENT_DEF(   SWITCHING_RULES, REQ,        ,        , 1, "on-switching-rules-request")        \
+/*	FLT_OTEL_EVENT_DEF(      FLT_START_BE, REQ,        ,        ,  , "") */                               \
+	FLT_OTEL_EVENT_DEF(        INSPECT_BE, REQ, REQ_CNT, REQ_CNT, 1, "on-backend-tcp-request")            \
+	FLT_OTEL_EVENT_DEF(   HTTP_PROCESS_BE, REQ, HRQ_HDR, HRQ_HDR, 1, "on-backend-http-request")           \
+/*	FLT_OTEL_EVENT_DEF(       HTTP_TARPIT, REQ,        ,        , 1, "on-http-tarpit-request") */         \
+	FLT_OTEL_EVENT_DEF(         SRV_RULES, REQ,        ,        , 1, "on-process-server-rules-request")   \
+	FLT_OTEL_EVENT_DEF(        HTTP_INNER, REQ,        ,        , 1, "on-http-process-request")           \
+	FLT_OTEL_EVENT_DEF(   PRST_RDP_COOKIE, REQ,        ,        , 1, "on-tcp-rdp-cookie-request")         \
+	FLT_OTEL_EVENT_DEF(    STICKING_RULES, REQ,        ,        , 1, "on-process-sticking-rules-request") \
+/*	FLT_OTEL_EVENT_DEF(     FLT_HTTP_HDRS, REQ,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(    HTTP_XFER_BODY, REQ,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(          WAIT_CLI, REQ,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(     FLT_XFER_DATA, REQ,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(           FLT_END, REQ,        ,        ,  , "") */                               \
+	FLT_OTEL_EVENT_DEF(      HTTP_HEADERS, REQ, HRQ_HDR, HRQ_HDR, 1, "on-http-headers-request")           \
+	FLT_OTEL_EVENT_DEF(          HTTP_END, REQ,        ,        , 1, "on-http-end-request")               \
+	FLT_OTEL_EVENT_DEF(   CLIENT_SESS_END, REQ,        ,        , 0, "on-client-session-end")             \
+	FLT_OTEL_EVENT_DEF(SERVER_UNAVAILABLE, REQ,        ,        , 0, "on-server-unavailable")             \
+	                                                                                                      \
+	/* Response analyzers */                                                                              \
+	FLT_OTEL_EVENT_DEF( SERVER_SESS_START, RES,        , SRV_CON, 0, "on-server-session-start")           \
+/*	FLT_OTEL_EVENT_DEF(      FLT_START_FE, RES,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(      FLT_START_BE, RES,        ,        ,  , "") */                               \
+	FLT_OTEL_EVENT_DEF(           INSPECT, RES, RES_CNT, RES_CNT, 0, "on-tcp-response")                   \
+	FLT_OTEL_EVENT_DEF(         WAIT_HTTP, RES,        ,        , 1, "on-http-wait-response")             \
+	FLT_OTEL_EVENT_DEF(       STORE_RULES, RES,        ,        , 1, "on-process-store-rules-response")   \
+	FLT_OTEL_EVENT_DEF(   HTTP_PROCESS_BE, RES, HRS_HDR, HRS_HDR, 1, "on-http-response")                  \
+	FLT_OTEL_EVENT_DEF(      HTTP_HEADERS, RES, HRS_HDR, HRS_HDR, 1, "on-http-headers-response")          \
+	FLT_OTEL_EVENT_DEF(          HTTP_END, RES,        ,        , 0, "on-http-end-response")              \
+	FLT_OTEL_EVENT_DEF(        HTTP_REPLY, RES,        ,        , 0, "on-http-reply")                     \
+/*	FLT_OTEL_EVENT_DEF(   HTTP_PROCESS_FE, RES,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(     FLT_HTTP_HDRS, RES,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(    HTTP_XFER_BODY, RES,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(          WAIT_CLI, RES,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(     FLT_XFER_DATA, RES,        ,        ,  , "") */                               \
+/*	FLT_OTEL_EVENT_DEF(           FLT_END, RES,        ,        ,  , "") */                               \
+	FLT_OTEL_EVENT_DEF(   SERVER_SESS_END, RES,        ,        , 0, "on-server-session-end")
+
+enum FLT_OTEL_EVENT_enum {
+#define FLT_OTEL_EVENT_DEF(a,b,c,d,e,f)   FLT_OTEL_EVENT_##b##_##a,
+	FLT_OTEL_EVENT_DEFINES
+	FLT_OTEL_EVENT_MAX
+#undef FLT_OTEL_EVENT_DEF
+};
+
+/* Sample data types associated with a scope event. */
+enum FLT_OTEL_EVENT_SAMPLE_enum {
+	FLT_OTEL_EVENT_SAMPLE_ATTRIBUTE = 0,
+	FLT_OTEL_EVENT_SAMPLE_EVENT,
+	FLT_OTEL_EVENT_SAMPLE_BAGGAGE,
+	FLT_OTEL_EVENT_SAMPLE_STATUS,
+};
+
+/* Per-event metadata mapping analyzer bits to filter event names. */
+struct flt_otel_event_data {
+	uint        an_bit;           /* Used channel analyser. */
+	const char *an_name;          /* Channel analyser name. */
+	uint        smp_opt_dir;      /* Fetch direction (request/response). */
+	uint        smp_val_fe;       /* Valid FE fetch location. */
+	uint        smp_val_be;       /* Valid BE fetch location. */
+	bool        flag_http_inject; /* Span context injection allowed. */
+	const char *name;             /* Filter event name. */
+};
+
+struct flt_otel_conf_scope;
+
+
+/* Per-event metadata table indexed by FLT_OTEL_EVENT_* constants. */
+extern const struct flt_otel_event_data flt_otel_event_data[FLT_OTEL_EVENT_MAX];
+
+
+/* Execute a single scope: create spans, record instruments, evaluate samples. */
+int flt_otel_scope_run(struct stream *s, struct filter *f, struct channel *chn, struct flt_otel_conf_scope *conf_scope, const struct timespec *ts_steady, const struct timespec *ts_system, uint dir, char **err);
+
+/* Run all scopes matching a filter event on the given stream and channel. */
+int flt_otel_event_run(struct stream *s, struct filter *f, struct channel *chn, int event, char **err);
+
+#endif /* _OTEL_EVENT_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/filter.h

@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_FILTER_H_
+#define _OTEL_FILTER_H_
+
+#define FLT_OTEL_FMT_NAME           "'" FLT_OTEL_OPT_NAME "' : "
+#define FLT_OTEL_FMT_TYPE           "'filter' : "
+#define FLT_OTEL_VAR_UUID           "sess", "otel", "uuid"
+#define FLT_OTEL_ALERT(f, ...)      ha_alert(FLT_OTEL_FMT_TYPE FLT_OTEL_FMT_NAME f "\n", ##__VA_ARGS__)
+
+#define FLT_OTEL_CONDITION_IF       "if"
+#define FLT_OTEL_CONDITION_UNLESS   "unless"
+
+/* Return codes for OTel filter operations. */
+enum FLT_OTEL_RET_enum {
+	FLT_OTEL_RET_ERROR  = -1,
+	FLT_OTEL_RET_WAIT   = 0,
+	FLT_OTEL_RET_IGNORE = 0,
+	FLT_OTEL_RET_OK     = 1,
+};
+
+/* Dump or iterate a named configuration list for debugging. */
+#define FLT_OTEL_DBG_LIST(d,m,p,t,v,f)                               \
+	do {                                                         \
+		if (LIST_ISEMPTY(&((d)->m##s))) {                    \
+			OTELC_DBG(DEBUG, p "- no " #m "s " t);       \
+		} else {                                             \
+			const struct flt_otel_conf_##m *v;           \
+			                                             \
+			OTELC_DBG(DEBUG, p "- " t " " #m "s: %s",    \
+			          flt_otel_list_dump(&((d)->m##s))); \
+			list_for_each_entry(v, &((d)->m##s), list)   \
+				do { f; } while (0);                 \
+		}                                                    \
+	} while (0)
+
+
+extern const char     *otel_flt_id;
+extern uint64_t        flt_otel_drop_cnt;
+extern struct flt_ops  flt_otel_ops;
+
+
+/* Check whether the OTel filter is disabled for a stream. */
+bool flt_otel_is_disabled(const struct filter *f FLT_OTEL_DBG_ARGS(, int event));
+
+#endif /* _OTEL_FILTER_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/group.h

@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_GROUP_H_
+#define _OTEL_GROUP_H_
+
+#define FLT_OTEL_ACTION_GROUP   "otel-group"
+
+/* Argument indices for the otel-group action rule. */
+enum FLT_OTEL_ARG_enum {
+	FLT_OTEL_ARG_FILTER_ID = 0,
+	FLT_OTEL_ARG_GROUP_ID,
+
+	FLT_OTEL_ARG_FLT_CONF = 0,
+	FLT_OTEL_ARG_CONF,
+	FLT_OTEL_ARG_GROUP,
+};
+
+/*
+ * A description of the macro arguments can be found in the structure
+ * flt_otel_group_data definition
+ */
+#define FLT_OTEL_GROUP_DEFINES                                                     \
+	FLT_OTEL_GROUP_DEF(ACT_F_TCP_REQ_CON, SMP_VAL_FE_CON_ACC, SMP_OPT_DIR_REQ) \
+	FLT_OTEL_GROUP_DEF(ACT_F_TCP_REQ_SES, SMP_VAL_FE_SES_ACC, SMP_OPT_DIR_REQ) \
+	FLT_OTEL_GROUP_DEF(ACT_F_TCP_REQ_CNT, SMP_VAL_FE_REQ_CNT, SMP_OPT_DIR_REQ) \
+	FLT_OTEL_GROUP_DEF(ACT_F_TCP_RES_CNT, SMP_VAL_BE_RES_CNT, SMP_OPT_DIR_RES) \
+	FLT_OTEL_GROUP_DEF(ACT_F_HTTP_REQ,    SMP_VAL_FE_HRQ_HDR, SMP_OPT_DIR_REQ) \
+	FLT_OTEL_GROUP_DEF(ACT_F_HTTP_RES,    SMP_VAL_BE_HRS_HDR, SMP_OPT_DIR_RES)
+
+/* Per-action-from metadata mapping action types to fetch directions. */
+struct flt_otel_group_data {
+	enum act_from act_from;    /* ACT_F_* */
+	uint          smp_val;     /* Valid FE/BE fetch location. */
+	uint          smp_opt_dir; /* Fetch direction (request/response). */
+};
+
+#endif /* _OTEL_GROUP_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/http.h

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_HTTP_H_
+#define _OTEL_HTTP_H_
+
+#ifndef DEBUG_OTEL
+#  define flt_otel_http_headers_dump(...)   while (0)
+#else
+/* Dump all HTTP headers from a channel for debugging. */
+void                   flt_otel_http_headers_dump(const struct channel *chn);
+#endif
+
+/* Extract HTTP headers matching a prefix into a text map. */
+struct otelc_text_map *flt_otel_http_headers_get(struct channel *chn, const char *prefix, size_t len, char **err);
+
+/* Set or replace an HTTP header in a channel. */
+int                    flt_otel_http_header_set(struct channel *chn, const char *prefix, const char *name, const char *value, char **err);
+
+/* Remove all HTTP headers matching a prefix from a channel. */
+int                    flt_otel_http_headers_remove(struct channel *chn, const char *prefix, char **err);
+
+#endif /* _OTEL_HTTP_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/include.h

@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_INCLUDE_H_
+#define _OTEL_INCLUDE_H_
+
+#include <errno.h>
+#include <stdbool.h>
+#include <math.h>
+#include <values.h>
+
+#include <haproxy/api.h>
+#include <haproxy/cfgparse.h>
+#include <haproxy/acl.h>
+#include <haproxy/cli.h>
+#include <haproxy/clock.h>
+#include <haproxy/filters.h>
+#include <haproxy/http_htx.h>
+#include <haproxy/http_rules.h>
+#include <haproxy/log.h>
+#include <haproxy/proxy.h>
+#include <haproxy/sample.h>
+#include <haproxy/tcp_rules.h>
+#include <haproxy/tools.h>
+#include <haproxy/vars.h>
+
+#include <opentelemetry-c-wrapper/include.h>
+
+#include "config.h"
+#include "debug.h"
+#include "define.h"
+#include "cli.h"
+#include "event.h"
+#include "conf.h"
+#include "conf_funcs.h"
+#include "filter.h"
+#include "group.h"
+#include "http.h"
+#include "otelc.h"
+#include "parser.h"
+#include "pool.h"
+#include "scope.h"
+#include "util.h"
+#include "vars.h"
+
+#endif /* _OTEL_INCLUDE_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/otelc.h

@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_OTELC_H_
+#define _OTEL_OTELC_H_
+
+/* Inject span context into a text map carrier. */
+int                        flt_otel_inject_text_map(const struct otelc_span *span, struct otelc_text_map_writer *carrier);
+
+/* Inject span context into an HTTP headers carrier. */
+int                        flt_otel_inject_http_headers(const struct otelc_span *span, struct otelc_http_headers_writer *carrier);
+
+/* Extract span context from a text map carrier. */
+struct otelc_span_context *flt_otel_extract_text_map(struct otelc_tracer *tracer, struct otelc_text_map_reader *carrier, const struct otelc_text_map *text_map);
+
+/* Extract span context from an HTTP headers carrier. */
+struct otelc_span_context *flt_otel_extract_http_headers(struct otelc_tracer *tracer, struct otelc_http_headers_reader *carrier, const struct otelc_text_map *text_map);
+
+#endif /* _OTEL_OTELC_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/parser.h

@@ -0,0 +1,221 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_PARSER_H_
+#define _OTEL_PARSER_H_
+
+#define FLT_OTEL_SCOPE                        "OTEL"
+
+/*
+ * filter FLT_OTEL_OPT_NAME FLT_OTEL_OPT_FILTER_ID <FLT_OTEL_OPT_FILTER_ID_DEFAULT> FLT_OTEL_OPT_CONFIG <file>
+ */
+#define FLT_OTEL_OPT_NAME                     "opentelemetry"
+#define FLT_OTEL_OPT_FILTER_ID                "id"
+#define FLT_OTEL_OPT_FILTER_ID_DEFAULT        "otel-filter"
+#define FLT_OTEL_OPT_CONFIG                   "config"
+
+#define FLT_OTEL_PARSE_SECTION_INSTR_ID       "otel-instrumentation"
+#define FLT_OTEL_PARSE_SECTION_GROUP_ID       "otel-group"
+#define FLT_OTEL_PARSE_SECTION_SCOPE_ID       "otel-scope"
+
+#define FLT_OTEL_PARSE_SPAN_ROOT              "root"
+#define FLT_OTEL_PARSE_SPAN_PARENT            "parent"
+#define FLT_OTEL_PARSE_SPAN_LINK              "link"
+#define FLT_OTEL_PARSE_INSTRUMENT_DESC        "desc"
+#define FLT_OTEL_PARSE_INSTRUMENT_VALUE       "value"
+#define FLT_OTEL_PARSE_INSTRUMENT_ATTR        "attr"
+#define FLT_OTEL_PARSE_INSTRUMENT_UNIT        "unit"
+#define FLT_OTEL_PARSE_INSTRUMENT_BOUNDS      "bounds"
+#define FLT_OTEL_PARSE_INSTRUMENT_AGGR        "aggr"
+#define FLT_OTEL_PARSE_LOG_RECORD_ID          "id"
+#define FLT_OTEL_PARSE_LOG_RECORD_EVENT       "event"
+#define FLT_OTEL_PARSE_LOG_RECORD_SPAN        "span"
+#define FLT_OTEL_PARSE_LOG_RECORD_ATTR        "attr"
+#define FLT_OTEL_PARSE_CTX_AUTONAME           "-"
+#define FLT_OTEL_PARSE_CTX_IGNORE_NAME        '-'
+#define FLT_OTEL_PARSE_CTX_USE_HEADERS        "use-headers"
+#define FLT_OTEL_PARSE_CTX_USE_VARS           "use-vars"
+#define FLT_OTEL_PARSE_OPTION_HARDERR         "hard-errors"
+#define FLT_OTEL_PARSE_OPTION_DISABLED        "disabled"
+#define FLT_OTEL_PARSE_OPTION_NOLOGNORM       "dontlog-normal"
+
+/*
+ * A description of the macro arguments can be found in the structure
+ * flt_otel_parse_data definition
+ */
+#define FLT_OTEL_PARSE_INSTR_DEFINES                                                                                                                                      \
+	FLT_OTEL_PARSE_INSTR_DEF(         ID, 0, CHAR, 2, 2, "otel-instrumentation", " <name>")                                                                           \
+	FLT_OTEL_PARSE_INSTR_DEF(        ACL, 0, CHAR, 3, 0, "acl",                  " <name> <criterion> [flags] [operator] <value> ...")                                \
+	FLT_OTEL_PARSE_INSTR_DEF(        LOG, 0, CHAR, 2, 0, "log",                  " { global | <addr> [len <len>] [format <fmt>] <facility> [<level> [<minlevel>]] }") \
+	FLT_OTEL_PARSE_INSTR_DEF(     CONFIG, 0, NONE, 2, 2, "config",               " <file>")                                                                           \
+	FLT_OTEL_PARSE_INSTR_DEF(     GROUPS, 0, NONE, 2, 0, "groups",               " <name> ...")                                                                       \
+	FLT_OTEL_PARSE_INSTR_DEF(     SCOPES, 0, NONE, 2, 0, "scopes",               " <name> ...")                                                                       \
+	FLT_OTEL_PARSE_INSTR_DEF( RATE_LIMIT, 0, NONE, 2, 2, "rate-limit",           " <value>")                                                                          \
+	FLT_OTEL_PARSE_INSTR_DEF(     OPTION, 0, NONE, 2, 2, "option",               " { disabled | dontlog-normal | hard-errors }")                                      \
+	FLT_OTEL_PARSE_INSTR_DEF(DEBUG_LEVEL, 0, NONE, 2, 2, "debug-level",          " <value>")
+
+#define FLT_OTEL_PARSE_GROUP_DEFINES                                             \
+	FLT_OTEL_PARSE_GROUP_DEF(    ID, 0, CHAR, 2, 2, "otel-group", " <name>") \
+	FLT_OTEL_PARSE_GROUP_DEF(SCOPES, 0, NONE, 2, 0, "scopes",   " <name> ...")
+
+#ifdef USE_OTEL_VARS
+#  define FLT_OTEL_PARSE_SCOPE_INJECT_HELP    " <name-prefix> [use-vars] [use-headers]"
+#  define FLT_OTEL_PARSE_SCOPE_EXTRACT_HELP   " <name-prefix> [use-vars | use-headers]"
+#else
+#  define FLT_OTEL_PARSE_SCOPE_INJECT_HELP    " <name-prefix> [use-headers]"
+#  define FLT_OTEL_PARSE_SCOPE_EXTRACT_HELP   " <name-prefix> [use-headers]"
+#endif
+
+/*
+ * The first argument of the FLT_OTEL_PARSE_SCOPE_STATUS_DEF() macro is defined
+ * as otelc_span_status_t in <opentelemetry-c-wrapper/span.h> .
+ */
+#define FLT_OTEL_PARSE_SCOPE_STATUS_DEFINES               \
+	FLT_OTEL_PARSE_SCOPE_STATUS_DEF(IGNORE, "ignore") \
+	FLT_OTEL_PARSE_SCOPE_STATUS_DEF( UNSET, "unset" ) \
+	FLT_OTEL_PARSE_SCOPE_STATUS_DEF(    OK, "ok"    ) \
+	FLT_OTEL_PARSE_SCOPE_STATUS_DEF( ERROR, "error" )
+
+/* Sentinel: instrument has not been created yet. */
+#define OTELC_METRIC_INSTRUMENT_UNSET         -1
+
+/* Sentinel: instrument creation is in progress by another thread. */
+#define OTELC_METRIC_INSTRUMENT_PENDING       -2
+
+/* Sentinel: update-form instrument (re-evaluates an existing one). */
+#define OTELC_METRIC_INSTRUMENT_UPDATE        0xff
+
+#define OTELC_METRIC_AGGREGATION_UNSET        -1
+
+/*
+ * Observable (asynchronous) instruments are not supported.  The OTel SDK
+ * invokes their callbacks from an external background thread that is not a
+ * HAProxy thread.  HAProxy sample fetches rely on internal per-thread-group
+ * state and return incorrect results when called from a non-HAProxy thread.
+ *
+ * Double-precision instruments are not supported because HAProxy sample fetches
+ * do not return double values.
+ */
+#define FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEFINES                            \
+	FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEF(UPDATE,           "update"   ) \
+	FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEF(COUNTER_UINT64,   "cnt_int"  ) \
+	FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEF(HISTOGRAM_UINT64, "hist_int" ) \
+	FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEF(UDCOUNTER_INT64,  "udcnt_int") \
+	FLT_OTEL_PARSE_SCOPE_INSTRUMENT_DEF(GAUGE_INT64,      "gauge_int")
+
+/*
+ * In case the possibility of working with OpenTelemetry context via HAProxy
+ * variables is not used, args_max member of the structure flt_otel_parse_data
+ * should be reduced for 'inject' keyword.  However, this is not critical
+ * because in this case the 'use-vars' argument cannot be entered anyway,
+ * so I will not complicate it here with additional definitions.
+ */
+#define FLT_OTEL_PARSE_SCOPE_DEFINES                                                                                                                                           \
+	FLT_OTEL_PARSE_SCOPE_DEF(          ID, 0, CHAR, 2, 2, "otel-scope",   " <name>")                                                                                       \
+	FLT_OTEL_PARSE_SCOPE_DEF(        SPAN, 0, NONE, 2, 7, "span",         " <name> [<reference>] [<link>] [root]")                                                         \
+	FLT_OTEL_PARSE_SCOPE_DEF(        LINK, 1, NONE, 2, 0,   "link",       " <span> ...")                                                                                   \
+	FLT_OTEL_PARSE_SCOPE_DEF(   ATTRIBUTE, 1, NONE, 3, 0,   "attribute",  " <key> <sample> ...")                                                                           \
+	FLT_OTEL_PARSE_SCOPE_DEF(       EVENT, 1, NONE, 4, 0,   "event",      " <name> <key> <sample> ...")                                                                    \
+	FLT_OTEL_PARSE_SCOPE_DEF(     BAGGAGE, 1,  VAR, 3, 0,   "baggage",    " <key> <sample> ...")                                                                           \
+	FLT_OTEL_PARSE_SCOPE_DEF(      INJECT, 1,  CTX, 2, 4,   "inject",     FLT_OTEL_PARSE_SCOPE_INJECT_HELP)                                                                \
+	FLT_OTEL_PARSE_SCOPE_DEF(     EXTRACT, 0,  CTX, 2, 3,   "extract",    FLT_OTEL_PARSE_SCOPE_EXTRACT_HELP)                                                               \
+	FLT_OTEL_PARSE_SCOPE_DEF(      STATUS, 1, NONE, 2, 0,   "status",     " <code> [<sample> ...]")                                                                        \
+	FLT_OTEL_PARSE_SCOPE_DEF(      FINISH, 0, NONE, 2, 0,   "finish",     " <name> ...")                                                                                   \
+	FLT_OTEL_PARSE_SCOPE_DEF(  INSTRUMENT, 0, NONE, 3, 0, "instrument",   " { update <name> [<attr> ...] | <type> <name> [<aggr>] [<desc>] [<unit>] <value> [<bounds>] }") \
+	FLT_OTEL_PARSE_SCOPE_DEF(  LOG_RECORD, 0, NONE, 3, 0, "log-record",   " <severity> [<id>] [<event>] [<span>] [<attr>] <sample> ...")                                   \
+	FLT_OTEL_PARSE_SCOPE_DEF(IDLE_TIMEOUT, 0, NONE, 2, 2, "idle-timeout", " <time>")                                                                                       \
+	FLT_OTEL_PARSE_SCOPE_DEF(         ACL, 0, CHAR, 3, 0, "acl",          " <name> <criterion> [flags] [operator] <value> ...")                                            \
+	FLT_OTEL_PARSE_SCOPE_DEF(    ON_EVENT, 0, NONE, 2, 0, "otel-event",   " <name> [{ if | unless } <condition>]")
+
+/* Invalid character check modes for identifier validation. */
+enum FLT_OTEL_PARSE_INVCHAR_enum {
+	FLT_OTEL_PARSE_INVALID_NONE,
+	FLT_OTEL_PARSE_INVALID_CHAR,
+	FLT_OTEL_PARSE_INVALID_DOM,
+	FLT_OTEL_PARSE_INVALID_CTX,
+	FLT_OTEL_PARSE_INVALID_VAR,
+};
+
+enum FLT_OTEL_PARSE_INSTR_enum {
+#define FLT_OTEL_PARSE_INSTR_DEF(a,b,c,d,e,f,g)   FLT_OTEL_PARSE_INSTR_##a,
+	FLT_OTEL_PARSE_INSTR_DEFINES
+#undef FLT_OTEL_PARSE_INSTR_DEF
+};
+
+enum FLT_OTEL_PARSE_GROUP_enum {
+#define FLT_OTEL_PARSE_GROUP_DEF(a,b,c,d,e,f,g)   FLT_OTEL_PARSE_GROUP_##a,
+	FLT_OTEL_PARSE_GROUP_DEFINES
+#undef FLT_OTEL_PARSE_GROUP_DEF
+};
+
+enum FLT_OTEL_PARSE_SCOPE_enum {
+#define FLT_OTEL_PARSE_SCOPE_DEF(a,b,c,d,e,f,g)   FLT_OTEL_PARSE_SCOPE_##a,
+	FLT_OTEL_PARSE_SCOPE_DEFINES
+#undef FLT_OTEL_PARSE_SCOPE_DEF
+};
+
+/* Context storage type flags for inject/extract operations. */
+enum FLT_OTEL_CTX_USE_enum {
+	FLT_OTEL_CTX_USE_VARS    = 1 << 0,
+	FLT_OTEL_CTX_USE_HEADERS = 1 << 1,
+};
+
+/* Logging state flags for the OTel filter. */
+enum FLT_OTEL_LOGGING_enum {
+	FLT_OTEL_LOGGING_OFF       = 0,
+	FLT_OTEL_LOGGING_ON        = 1 << 0,
+	FLT_OTEL_LOGGING_NOLOGNORM = 1 << 1,
+};
+
+/* Keyword metadata used by the configuration section parsers. */
+struct flt_otel_parse_data {
+	int         keyword;       /* Keyword index. */
+	bool        flag_check_id; /* Whether the group ID must be defined for the keyword. */
+	int         check_name;    /* Checking allowed characters in the name. */
+	int         args_min;      /* The minimum number of arguments required. */
+	int         args_max;      /* The maximum number of arguments allowed. */
+	const char *name;          /* Keyword name. */
+	const char *usage;         /* Usage text to be printed in case of an error. */
+};
+
+#define FLT_OTEL_PARSE_KEYWORD(n,s)           (strcmp(args[n], (s)) == 0)
+
+#define FLT_OTEL_PARSE_WARNING(f, ...) \
+	ha_warning("parsing [%s:%d] : " FLT_OTEL_FMT_TYPE FLT_OTEL_FMT_NAME "'" f "'\n", ##__VA_ARGS__);
+
+#define FLT_OTEL_PARSE_ALERT(f, ...)                                                                           \
+	do {                                                                                                   \
+		ha_alert("parsing [%s:%d] : " FLT_OTEL_FMT_TYPE FLT_OTEL_FMT_NAME "'" f "'\n", ##__VA_ARGS__); \
+		                                                                                               \
+		retval |= ERR_ABORT | ERR_ALERT;                                                               \
+	} while (0)
+
+#define FLT_OTEL_POST_PARSE_ALERT(f, ...) \
+	FLT_OTEL_PARSE_ALERT(f, flt_otel_current_config->cfg_file, ##__VA_ARGS__)
+
+#define FLT_OTEL_PARSE_ERR(e,f, ...)                            \
+	do {                                                    \
+		if (*(e) == NULL)                               \
+			(void)memprintf((e), f, ##__VA_ARGS__); \
+		                                                \
+		retval |= ERR_ABORT | ERR_ALERT;                \
+	} while (0)
+
+#define FLT_OTEL_PARSE_IFERR_ALERT()                         \
+	do {                                                 \
+		if (err == NULL)                             \
+			break;                               \
+		                                             \
+		FLT_OTEL_PARSE_ALERT("%s", file, line, err); \
+		FLT_OTEL_ERR_FREE(err);                      \
+	} while (0)
+
+#endif /* _OTEL_PARSER_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/pool.h

@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_POOL_H_
+#define _OTEL_POOL_H_
+
+#define FLT_OTEL_POOL_INIT(p,n,s,r)                                                       \
+	do {                                                                              \
+		if (((r) == FLT_OTEL_RET_OK) && ((p) == NULL)) {                          \
+			(p) = create_pool(n, (s), MEM_F_SHARED);                          \
+			if ((p) == NULL)                                                  \
+				(r) = FLT_OTEL_RET_ERROR;                                 \
+			                                                                  \
+			OTELC_DBG(DEBUG, #p " %p %u", (p), FLT_OTEL_DEREF((p), size, 0)); \
+		}                                                                         \
+	} while (0)
+
+#define FLT_OTEL_POOL_DESTROY(p)                                       \
+	do {                                                           \
+		if ((p) != NULL) {                                     \
+			OTELC_DBG(DEBUG, #p " %p %u", (p), (p)->size); \
+			                                               \
+			pool_destroy(p);                               \
+			(p) = NULL;                                    \
+		}                                                      \
+	} while (0)
+
+
+extern struct pool_head *pool_head_otel_scope_span __read_mostly;
+extern struct pool_head *pool_head_otel_scope_context __read_mostly;
+extern struct pool_head *pool_head_otel_runtime_context __read_mostly;
+extern struct pool_head *pool_head_otel_span_context __read_mostly;
+
+
+/* Allocate memory from a pool with optional zeroing. */
+void          *flt_otel_pool_alloc(struct pool_head *pool, size_t size, bool flag_clear, char **err);
+
+/* Duplicate a string into pool-allocated memory. */
+void          *flt_otel_pool_strndup(struct pool_head *pool, const char *s, size_t size, char **err);
+
+/* Release pool-allocated memory and clear the pointer. */
+void           flt_otel_pool_free(struct pool_head *pool, void **ptr);
+
+/* Initialize OTel filter memory pools. */
+int            flt_otel_pool_init(void);
+
+/* Destroy OTel filter memory pools. */
+void           flt_otel_pool_destroy(void);
+
+/* Log debug information about OTel filter memory pools. */
+#ifndef DEBUG_OTEL
+#  define flt_otel_pool_info()   while (0)
+#else
+void           flt_otel_pool_info(void);
+#endif
+
+/* Allocate a trash buffer with optional zeroing. */
+struct buffer *flt_otel_trash_alloc(bool flag_clear, char **err);
+
+/* Release a trash buffer and clear the pointer. */
+void           flt_otel_trash_free(struct buffer **ptr);
+
+#endif /* _OTEL_POOL_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/scope.h

@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_SCOPE_H_
+#define _OTEL_SCOPE_H_
+
+#define FLT_OTEL_SCOPE_SPAN_FINISH_REQ       "*req*"
+#define FLT_OTEL_SCOPE_SPAN_FINISH_RES       "*res*"
+#define FLT_OTEL_SCOPE_SPAN_FINISH_ALL       "*"
+
+#define FLT_OTEL_RT_CTX(p)                   ((struct flt_otel_runtime_context *)(p))
+
+#define FLT_OTEL_DBG_SCOPE_SPAN(h,p)                                \
+	OTELC_DBG(DEBUG, h "%p:{ '%s' %zu %u %hhu %p %p %p }", (p), \
+	          FLT_OTEL_STR_HDR_ARGS(p, id), (p)->smp_opt_dir,   \
+	          (p)->flag_finish, (p)->span, (p)->ref_span, (p)->ref_ctx)
+
+#define FLT_OTEL_DBG_SCOPE_CONTEXT(h,p)                           \
+	OTELC_DBG(DEBUG, h "%p:{ '%s' %zu %u %hhu %p }", (p),     \
+	          FLT_OTEL_STR_HDR_ARGS(p, id), (p)->smp_opt_dir, \
+	          (p)->flag_finish, (p)->context)
+
+#define FLT_OTEL_DBG_SCOPE_DATA_EVENT(h,p)                    \
+	OTELC_DBG(DEBUG, h "%p:{ '%s' %p %zu %zu %s }", &(p), \
+	          (p).name, (p).attr, (p).cnt, (p).size,      \
+	          flt_otel_list_dump(&((p).list)))
+
+#define FLT_OTEL_DBG_SCOPE_DATA_STATUS(h,p) \
+	OTELC_DBG(DEBUG, h "%p:{ %d '%s' }", (p), (p)->code, OTELC_STR_ARG((p)->description))
+
+#define FLT_OTEL_DBG_SCOPE_DATA_KV_FMT       "%p:{ %p %zu %zu }"
+#define FLT_OTEL_DBG_SCOPE_DATA_KV_ARGS(p)   &(p), (p).attr, (p).cnt, (p).size
+#define FLT_OTEL_DBG_SCOPE_DATA(h,p)                                                                                   \
+	OTELC_DBG(DEBUG, h "%p:{ " FLT_OTEL_DBG_SCOPE_DATA_KV_FMT " " FLT_OTEL_DBG_SCOPE_DATA_KV_FMT " %s %s }", (p), \
+	          FLT_OTEL_DBG_SCOPE_DATA_KV_ARGS((p)->baggage), FLT_OTEL_DBG_SCOPE_DATA_KV_ARGS((p)->attributes),    \
+	          flt_otel_list_dump(&((p)->events)), flt_otel_list_dump(&((p)->links)))
+
+#define FLT_OTEL_DBG_RUNTIME_CONTEXT(h,p)                                                     \
+	OTELC_DBG(DEBUG, h "%p:{ %p %p '%s' %hhu %hhu 0x%02hhx 0x%08x %u %d %s %s }", (p),    \
+	          (p)->stream, (p)->filter, (p)->uuid, (p)->flag_harderr, (p)->flag_disabled, \
+	          (p)->logging, (p)->analyzers, (p)->idle_timeout, (p)->idle_exp,             \
+	          flt_otel_list_dump(&((p)->spans)), flt_otel_list_dump(&((p)->contexts)))
+
+/* Anonymous struct containing a const string pointer and its length. */
+#define FLT_OTEL_CONST_STR_HDR(p)    \
+	struct {                     \
+		const char *p;       \
+		size_t      p##_len; \
+	}
+
+
+/* Growable key-value array for span attributes or baggage. */
+struct flt_otel_scope_data_kv {
+	struct otelc_kv *attr; /* Key-value array for storing attributes. */
+	size_t           cnt;  /* Number of currently used array elements. */
+	size_t           size; /* Total number of array elements. */
+};
+
+/* Named event with its own key-value attribute array. */
+struct flt_otel_scope_data_event {
+	char            *name; /* Event name, not used for other data types. */
+	struct otelc_kv *attr; /* Key-value array for storing attributes. */
+	size_t           cnt;  /* Number of currently used array elements. */
+	size_t           size; /* Total number of array elements. */
+	struct list      list; /* Used to chain this structure. */
+};
+
+/* Span link referencing another span or span context. */
+struct flt_otel_scope_data_link {
+	struct otelc_span         *span;    /* Linked span, or NULL. */
+	struct otelc_span_context *context; /* Linked span context, or NULL. */
+	struct list                list;    /* Used to chain this structure. */
+};
+
+/* Span status code and description. */
+struct flt_otel_scope_data_status {
+	int   code;        /* OTELC_SPAN_STATUS_* value. */
+	char *description; /* Span status description string. */
+};
+
+/* Aggregated runtime data collected during scope execution. */
+struct flt_otel_scope_data {
+	struct flt_otel_scope_data_kv     baggage;    /* Defined scope baggage. */
+	struct flt_otel_scope_data_kv     attributes; /* Defined scope attributes. */
+	struct list                       events;     /* Defined scope events. */
+	struct list                       links;      /* Defined scope links. */
+	struct flt_otel_scope_data_status status;     /* Defined scope status. */
+};
+
+/* flt_otel_runtime_context->spans */
+struct flt_otel_scope_span {
+	FLT_OTEL_CONST_STR_HDR(id);             /* The span operation name/len. */
+	uint                       smp_opt_dir; /* SMP_OPT_DIR_RE(Q|S) */
+	bool                       flag_finish; /* Whether the span is marked for completion. */
+	struct otelc_span         *span;        /* The current span. */
+	struct otelc_span         *ref_span;    /* Span to which the current span refers. */
+	struct otelc_span_context *ref_ctx;     /* Span context to which the current span refers. */
+	struct list                list;        /* Used to chain this structure. */
+};
+
+/* flt_otel_runtime_context->contexts */
+struct flt_otel_scope_context {
+	FLT_OTEL_CONST_STR_HDR(id);             /* The span context name/len. */
+	uint                       smp_opt_dir; /* SMP_OPT_DIR_RE(Q|S) */
+	bool                       flag_finish; /* Whether the span context is marked for completion. */
+	struct otelc_span_context *context;     /* The current span context. */
+	struct list                list;        /* Used to chain this structure. */
+};
+
+/* The runtime filter context attached to a stream. */
+struct flt_otel_runtime_context {
+	struct stream *stream;        /* The stream to which the filter is attached. */
+	struct filter *filter;        /* The OpenTelemetry filter. */
+	char           uuid[40];      /* Randomly generated UUID. */
+	bool           flag_harderr;  /* [0 1] */
+	bool           flag_disabled; /* [0 1] */
+	uint8_t        logging;       /* [0 1 3] */
+	uint           analyzers;     /* Executed channel analyzers. */
+	uint           idle_timeout;  /* Idle timeout interval in milliseconds (0 = off). */
+	int            idle_exp;      /* Tick at which the next idle timeout fires. */
+	struct list    spans;         /* The scope spans. */
+	struct list    contexts;      /* The scope contexts. */
+};
+
+
+#ifndef DEBUG_OTEL
+#  define flt_otel_scope_data_dump(...)   while (0)
+#else
+/* Dump scope data contents for debugging. */
+void                             flt_otel_scope_data_dump(const struct flt_otel_scope_data *data);
+#endif
+
+/* Allocate and initialize a runtime context for a stream. */
+struct flt_otel_runtime_context *flt_otel_runtime_context_init(struct stream *s, struct filter *f, char **err);
+
+/* Free the runtime context attached to a filter. */
+void                             flt_otel_runtime_context_free(struct filter *f);
+
+/* Allocate and initialize a scope span in the runtime context. */
+struct flt_otel_scope_span      *flt_otel_scope_span_init(struct flt_otel_runtime_context *rt_ctx, const char *id, size_t id_len, const char *ref_id, size_t ref_id_len, uint dir, char **err);
+
+/* Free a scope span and remove it from the runtime context. */
+void                             flt_otel_scope_span_free(struct flt_otel_scope_span **ptr);
+
+/* Allocate and initialize a scope context in the runtime context. */
+struct flt_otel_scope_context   *flt_otel_scope_context_init(struct flt_otel_runtime_context *rt_ctx, struct otelc_tracer *tracer, const char *id, size_t id_len, const struct otelc_text_map *text_map, uint dir, char **err);
+
+/* Free a scope context and remove it from the runtime context. */
+void                             flt_otel_scope_context_free(struct flt_otel_scope_context **ptr);
+
+/* Initialize scope data arrays and lists. */
+void                             flt_otel_scope_data_init(struct flt_otel_scope_data *ptr);
+
+/* Free all scope data contents. */
+void                             flt_otel_scope_data_free(struct flt_otel_scope_data *ptr);
+
+/* Mark a span for finishing by name in the runtime context. */
+int                              flt_otel_scope_finish_mark(const struct flt_otel_runtime_context *rt_ctx, const char *id, size_t id_len);
+
+/* End all spans that have been marked for finishing. */
+void                             flt_otel_scope_finish_marked(const struct flt_otel_runtime_context *rt_ctx, const struct timespec *ts_finish);
+
+/* Free scope spans and contexts no longer needed by a channel. */
+void                             flt_otel_scope_free_unused(struct flt_otel_runtime_context *rt_ctx, struct channel *chn);
+
+#endif /* _OTEL_SCOPE_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/util.h

@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_UTIL_H_
+#define _OTEL_UTIL_H_
+
+#define FLT_OTEL_HTTP_METH_DEFINES      \
+	FLT_OTEL_HTTP_METH_DEF(OPTIONS) \
+	FLT_OTEL_HTTP_METH_DEF(GET)     \
+	FLT_OTEL_HTTP_METH_DEF(HEAD)    \
+	FLT_OTEL_HTTP_METH_DEF(POST)    \
+	FLT_OTEL_HTTP_METH_DEF(PUT)     \
+	FLT_OTEL_HTTP_METH_DEF(DELETE)  \
+	FLT_OTEL_HTTP_METH_DEF(TRACE)   \
+	FLT_OTEL_HTTP_METH_DEF(CONNECT)
+
+/* Iterate over all OTel filter configurations across all proxies. */
+#define FLT_OTEL_PROXIES_LIST_START()                                           \
+	do {                                                                    \
+		struct flt_conf *fconf;                                         \
+		struct proxy    *px;                                            \
+		                                                                \
+		for (px = proxies_list; px != NULL; px = px->next)              \
+			list_for_each_entry(fconf, &(px->filter_configs), list) \
+				if (fconf->id == otel_flt_id) {                 \
+					struct flt_otel_conf *conf = fconf->conf;
+#define FLT_OTEL_PROXIES_LIST_END() \
+				}   \
+	} while (0)
+
+#ifdef DEBUG_OTEL
+#  define FLT_OTEL_ARGS_DUMP()   do { if (otelc_dbg_level & (1 << OTELC_DBG_LEVEL_LOG)) flt_otel_args_dump((const char **)args); } while (0)
+#else
+#  define FLT_OTEL_ARGS_DUMP()   while (0)
+#endif
+
+
+#ifndef DEBUG_OTEL
+#  define flt_otel_filters_dump()   while (0)
+#else
+/* Dump configuration arguments for debugging. */
+void        flt_otel_args_dump(const char **args);
+
+/* Dump all OTel filter configurations across all proxies. */
+void        flt_otel_filters_dump(void);
+
+/* Return a label string identifying a channel direction. */
+const char *flt_otel_chn_label(const struct channel *chn);
+
+/* Return the proxy mode string for a stream. */
+const char *flt_otel_pr_mode(const struct stream *s);
+
+/* Return the stream processing position as a string. */
+const char *flt_otel_stream_pos(const struct stream *s);
+
+/* Return the filter type string for a filter instance. */
+const char *flt_otel_type(const struct filter *f);
+
+/* Return the analyzer name string for an analyzer bit. */
+const char *flt_otel_analyzer(uint an_bit);
+
+/* Dump a linked list of configuration items as a string. */
+const char *flt_otel_list_dump(const struct list *head);
+#endif
+
+/* Count the number of non-NULL arguments in an argument array. */
+int         flt_otel_args_count(const char **args);
+
+/* Concatenate argument array elements into a single string. */
+int         flt_otel_args_concat(const char **args, int idx, int n, char **str);
+
+/* Comparator for qsort: ascending order of doubles with epsilon tolerance. */
+int         flt_otel_qsort_compar_double(const void *a, const void *b);
+
+/* Parse a string to double with range validation. */
+bool        flt_otel_strtod(const char *nptr, double *value, double limit_min, double limit_max, char **err);
+
+/* Parse a string to int64_t with range validation. */
+bool        flt_otel_strtoll(const char *nptr, int64_t *value, int64_t limit_min, int64_t limit_max, char **err);
+
+/* Convert sample data to a string representation. */
+int         flt_otel_sample_to_str(const struct sample_data *data, char *value, size_t size, char **err);
+
+/* Convert sample data to an OTel value. */
+int         flt_otel_sample_to_value(const char *key, const struct sample_data *data, struct otelc_value *value, char **err);
+
+/* Add a key-value pair to a growable key-value array. */
+int         flt_otel_sample_add_kv(struct flt_otel_scope_data_kv *kv, const char *key, const struct otelc_value *value);
+
+/* Evaluate a sample definition into an OTel value. */
+int         flt_otel_sample_eval(struct stream *s, uint dir, struct flt_otel_conf_sample *sample, bool flag_native, struct otelc_value *value, char **err);
+
+/* Evaluate a sample expression and add the result to scope data. */
+int         flt_otel_sample_add(struct stream *s, uint dir, struct flt_otel_conf_sample *sample, struct flt_otel_scope_data *data, int type, char **err);
+
+#endif /* _OTEL_UTIL_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/include/vars.h

@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#ifndef _OTEL_VARS_H_
+#define _OTEL_VARS_H_
+
+#define FLT_OTEL_VARS_SCOPE       "txn"
+#define FLT_OTEL_VAR_CHAR_DASH    'D'
+#define FLT_OTEL_VAR_CHAR_SPACE   'S'
+
+#ifndef USE_OTEL_VARS_NAME
+#  define FLT_OTEL_VAR_CTX_SIZE   int8_t
+
+/* Context buffer for storing a single variable value during iteration. */
+struct flt_otel_ctx {
+	char value[BUFSIZ]; /* Variable value string. */
+	int  value_len;     /* Length of the value string. */
+};
+
+/* Callback type invoked for each context variable during iteration. */
+typedef int (*flt_otel_ctx_loop_cb)(struct sample *, size_t, const char *, const char *, const char *, FLT_OTEL_VAR_CTX_SIZE, char **, void *);
+#endif /* !USE_OTEL_VARS_NAME */
+
+
+#ifndef DEBUG_OTEL
+#  define flt_otel_vars_dump(...)   while (0)
+#else
+/* Dump all OTel-related variables for a stream. */
+void                   flt_otel_vars_dump(struct stream *s);
+#endif
+
+/* Register a HAProxy variable for OTel context storage. */
+int                    flt_otel_var_register(const char *scope, const char *prefix, const char *name, char **err);
+
+/* Set an OTel context variable on a stream. */
+int                    flt_otel_var_set(struct stream *s, const char *scope, const char *prefix, const char *name, const char *value, uint opt, char **err);
+
+/* Unset all OTel context variables matching a prefix on a stream. */
+int                    flt_otel_vars_unset(struct stream *s, const char *scope, const char *prefix, uint opt, char **err);
+
+/* Retrieve all OTel context variables matching a prefix into a text map. */
+struct otelc_text_map *flt_otel_vars_get(struct stream *s, const char *scope, const char *prefix, uint opt, char **err);
+
+#endif /* _OTEL_VARS_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/cli.c

@@ -0,0 +1,457 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+/***
+ * NAME
+ *   flt_otel_cli_set_msg - CLI response message setter
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_set_msg(struct appctx *appctx, char *err, char *msg)
+ *
+ * ARGUMENTS
+ *   appctx - CLI application context
+ *   err    - error message string (or NULL)
+ *   msg    - informational message string (or NULL)
+ *
+ * DESCRIPTION
+ *   Sets the CLI response message and state for the given <appctx>.  If <err>
+ *   is non-NULL, it is passed to cli_dynerr() and <msg> is freed; otherwise
+ *   <msg> is passed to cli_dynmsg() at LOG_INFO severity.  When neither message
+ *   is available, the function returns 0 without changing state.
+ *
+ * RETURN VALUE
+ *   Returns 1 when a message was set, or 0 when both pointers were NULL.
+ */
+static int flt_otel_cli_set_msg(struct appctx *appctx, char *err, char *msg)
+{
+	OTELC_FUNC("%p, %p, %p", appctx, err, msg);
+
+	if ((appctx == NULL) || ((err == NULL) && (msg == NULL)))
+		OTELC_RETURN_INT(0);
+
+	if (err != NULL) {
+		OTELC_DBG(INFO, "err(%d): \"%s\"", appctx->st0, err);
+
+		OTELC_SFREE(msg);
+		OTELC_RETURN_INT(cli_dynerr(appctx, err));
+	}
+
+	OTELC_DBG(INFO, "msg(%d): \"%s\"", appctx->st0, msg);
+
+	OTELC_RETURN_INT(cli_dynmsg(appctx, LOG_INFO, msg));
+}
+
+
+#ifdef DEBUG_OTEL
+
+/***
+ * NAME
+ *   flt_otel_cli_parse_debug - CLI debug level handler
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_parse_debug(char **args, char *payload, struct appctx *appctx, void *private)
+ *
+ * ARGUMENTS
+ *   args    - CLI command arguments array
+ *   payload - CLI command payload string
+ *   appctx  - CLI application context
+ *   private - unused private data pointer
+ *
+ * DESCRIPTION
+ *   Handles the "otel debug [level]" CLI command.  When a level argument is
+ *   provided in <args[2]>, parses it as an integer in the range
+ *   [0, OTELC_DBG_LEVEL_MASK] and atomically stores it as the global debug
+ *   level.  Setting a level requires admin access level.  When no argument is
+ *   given, reports the current debug level.  The response message includes the
+ *   debug level in both decimal and hexadecimal format.
+ *
+ * RETURN VALUE
+ *   Returns 1, or 0 on memory allocation failure.
+ */
+static int flt_otel_cli_parse_debug(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	char *err = NULL, *msg = NULL;
+
+	OTELC_FUNC("%p, \"%s\", %p, %p", args, OTELC_STR_ARG(payload), appctx, private);
+
+	FLT_OTEL_ARGS_DUMP();
+
+	if (FLT_OTEL_ARG_ISVALID(2)) {
+		int64_t value;
+
+		if (!cli_has_level(appctx, ACCESS_LVL_ADMIN))
+			OTELC_RETURN_INT(1);
+
+		if (flt_otel_strtoll(args[2], &value, 0, OTELC_DBG_LEVEL_MASK, &err)) {
+			_HA_ATOMIC_STORE(&otelc_dbg_level, (int)value);
+
+			(void)memprintf(&msg, FLT_OTEL_CLI_CMD " : debug level set to %d (0x%04x)", (int)value, (int)value);
+		}
+	} else {
+		int value = _HA_ATOMIC_LOAD(&otelc_dbg_level);
+
+		(void)memprintf(&msg, FLT_OTEL_CLI_CMD " : current debug level is %d (0x%04x)", value, value);
+	}
+
+	OTELC_RETURN_INT(flt_otel_cli_set_msg(appctx, err, msg));
+}
+
+#endif /* DEBUG_OTEL */
+
+
+/***
+ * NAME
+ *   flt_otel_cli_parse_disabled - CLI enable/disable handler
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_parse_disabled(char **args, char *payload, struct appctx *appctx, void *private)
+ *
+ * ARGUMENTS
+ *   args    - CLI command arguments array
+ *   payload - CLI command payload string
+ *   appctx  - CLI application context
+ *   private - boolean flag cast to pointer (1 = disable, 0 = enable)
+ *
+ * DESCRIPTION
+ *   Handles the "otel enable" and "otel disable" CLI commands.  The <private>
+ *   parameter determines the action: a value of 1 disables the filter, 0
+ *   enables it.  Requires admin access level.  The flag_disabled field is
+ *   atomically updated for all OTel filter instances across all proxies.
+ *
+ * RETURN VALUE
+ *   Returns 1, or 0 if no OTel filter instances are configured or on memory
+ *   allocation failure.
+ */
+static int flt_otel_cli_parse_disabled(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	char *msg = NULL;
+	bool  value = (uintptr_t)private;
+
+	OTELC_FUNC("%p, \"%s\", %p, %p", args, OTELC_STR_ARG(payload), appctx, private);
+
+	FLT_OTEL_ARGS_DUMP();
+
+	if (!cli_has_level(appctx, ACCESS_LVL_ADMIN))
+		OTELC_RETURN_INT(1);
+
+	FLT_OTEL_PROXIES_LIST_START() {
+		_HA_ATOMIC_STORE(&(conf->instr->flag_disabled), value);
+
+		(void)memprintf(&msg, "%s%s" FLT_OTEL_CLI_CMD " : filter %sabled", FLT_OTEL_CLI_MSG_CAT(msg), value ? "dis" : "en");
+	} FLT_OTEL_PROXIES_LIST_END();
+
+	OTELC_RETURN_INT(flt_otel_cli_set_msg(appctx, NULL, msg));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_cli_parse_option - CLI error mode handler
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_parse_option(char **args, char *payload, struct appctx *appctx, void *private)
+ *
+ * ARGUMENTS
+ *   args    - CLI command arguments array
+ *   payload - CLI command payload string
+ *   appctx  - CLI application context
+ *   private - boolean flag cast to pointer (1 = hard-errors, 0 = soft-errors)
+ *
+ * DESCRIPTION
+ *   Handles the "otel hard-errors" and "otel soft-errors" CLI commands.  The
+ *   <private> parameter determines the error mode: a value of 1 enables
+ *   hard-error mode (filter failure aborts the stream), 0 enables soft-error
+ *   mode (failures are silently ignored).  Requires admin access level.  The
+ *   flag_harderr field is atomically updated for all OTel filter instances
+ *   across all proxies.
+ *
+ * RETURN VALUE
+ *   Returns 1, or 0 if no OTel filter instances are configured or on memory
+ *   allocation failure.
+ */
+static int flt_otel_cli_parse_option(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	char *msg = NULL;
+	bool  value = (uintptr_t)private;
+
+	OTELC_FUNC("%p, \"%s\", %p, %p", args, OTELC_STR_ARG(payload), appctx, private);
+
+	FLT_OTEL_ARGS_DUMP();
+
+	if (!cli_has_level(appctx, ACCESS_LVL_ADMIN))
+		OTELC_RETURN_INT(1);
+
+	FLT_OTEL_PROXIES_LIST_START() {
+		_HA_ATOMIC_STORE(&(conf->instr->flag_harderr), value);
+
+		(void)memprintf(&msg, "%s%s" FLT_OTEL_CLI_CMD " : filter set %s-errors", FLT_OTEL_CLI_MSG_CAT(msg), value ? "hard" : "soft");
+	} FLT_OTEL_PROXIES_LIST_END();
+
+	OTELC_RETURN_INT(flt_otel_cli_set_msg(appctx, NULL, msg));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_cli_parse_logging - CLI logging state handler
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_parse_logging(char **args, char *payload, struct appctx *appctx, void *private)
+ *
+ * ARGUMENTS
+ *   args    - CLI command arguments array
+ *   payload - CLI command payload string
+ *   appctx  - CLI application context
+ *   private - unused private data pointer
+ *
+ * DESCRIPTION
+ *   Handles the "otel logging [state]" CLI command.  When a state argument is
+ *   provided in <args[2]>, it is matched against "off", "on", or "nolognorm"
+ *   and the logging field is atomically updated for all OTel filter instances.
+ *   Setting a value requires admin access level.  When no argument is given,
+ *   reports the current logging state for all instances.  Invalid values
+ *   produce an error with the accepted options listed.
+ *
+ * RETURN VALUE
+ *   Returns 1, or 0 if no OTel filter instances are configured (and no error
+ *   occurred) or on memory allocation failure.
+ */
+static int flt_otel_cli_parse_logging(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	char    *err = NULL, *msg = NULL;
+	bool     flag_set = false;
+	uint8_t  value;
+
+	OTELC_FUNC("%p, \"%s\", %p, %p", args, OTELC_STR_ARG(payload), appctx, private);
+
+	FLT_OTEL_ARGS_DUMP();
+
+	if (FLT_OTEL_ARG_ISVALID(2)) {
+		if (!cli_has_level(appctx, ACCESS_LVL_ADMIN))
+			OTELC_RETURN_INT(1);
+
+		if (strcasecmp(args[2], FLT_OTEL_CLI_LOGGING_OFF) == 0) {
+			flag_set = true;
+			value    = FLT_OTEL_LOGGING_OFF;
+		}
+		else if (strcasecmp(args[2], FLT_OTEL_CLI_LOGGING_ON) == 0) {
+			flag_set = true;
+			value    = FLT_OTEL_LOGGING_ON;
+		}
+		else if (strcasecmp(args[2], FLT_OTEL_CLI_LOGGING_NOLOGNORM) == 0) {
+			flag_set = true;
+			value    = FLT_OTEL_LOGGING_ON | FLT_OTEL_LOGGING_NOLOGNORM;
+		}
+		else {
+			(void)memprintf(&err, "'%s' : invalid value, use <" FLT_OTEL_CLI_LOGGING_OFF " | " FLT_OTEL_CLI_LOGGING_ON " | " FLT_OTEL_CLI_LOGGING_NOLOGNORM ">", args[2]);
+		}
+
+		if (flag_set) {
+			FLT_OTEL_PROXIES_LIST_START() {
+				_HA_ATOMIC_STORE(&(conf->instr->logging), value);
+
+				(void)memprintf(&msg, "%s%s" FLT_OTEL_CLI_CMD " : logging is %s", FLT_OTEL_CLI_MSG_CAT(msg), FLT_OTEL_CLI_LOGGING_STATE(value));
+			} FLT_OTEL_PROXIES_LIST_END();
+		}
+	} else {
+		FLT_OTEL_PROXIES_LIST_START() {
+			value = _HA_ATOMIC_LOAD(&(conf->instr->logging));
+
+			(void)memprintf(&msg, "%s%s" FLT_OTEL_CLI_CMD " : logging is currently %s", FLT_OTEL_CLI_MSG_CAT(msg), FLT_OTEL_CLI_LOGGING_STATE(value));
+		} FLT_OTEL_PROXIES_LIST_END();
+	}
+
+	OTELC_RETURN_INT(flt_otel_cli_set_msg(appctx, err, msg));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_cli_parse_rate - CLI rate limit handler
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_parse_rate(char **args, char *payload, struct appctx *appctx, void *private)
+ *
+ * ARGUMENTS
+ *   args    - CLI command arguments array
+ *   payload - CLI command payload string
+ *   appctx  - CLI application context
+ *   private - unused private data pointer
+ *
+ * DESCRIPTION
+ *   Handles the "otel rate [value]" CLI command.  When a value argument is
+ *   provided in <args[2]>, it is parsed as a floating-point number in the
+ *   range [0.0, 100.0], converted to a fixed-point uint32_t representation,
+ *   and atomically stored as the rate limit for all OTel filter instances.
+ *   Setting a value requires admin access level.  When no argument is given,
+ *   reports the current rate limit percentage for all instances.
+ *
+ * RETURN VALUE
+ *   Returns 1, or 0 if no OTel filter instances are configured (and no error
+ *   occurred) or on memory allocation failure.
+ */
+static int flt_otel_cli_parse_rate(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	char *err = NULL, *msg = NULL;
+
+	OTELC_FUNC("%p, \"%s\", %p, %p", args, OTELC_STR_ARG(payload), appctx, private);
+
+	FLT_OTEL_ARGS_DUMP();
+
+	if (FLT_OTEL_ARG_ISVALID(2)) {
+		double value;
+
+		if (!cli_has_level(appctx, ACCESS_LVL_ADMIN))
+			OTELC_RETURN_INT(1);
+
+		if (flt_otel_strtod(args[2], &value, 0.0, 100.0, &err)) {
+			FLT_OTEL_PROXIES_LIST_START() {
+				_HA_ATOMIC_STORE(&(conf->instr->rate_limit), FLT_OTEL_FLOAT_U32(value));
+
+				(void)memprintf(&msg, "%s%s" FLT_OTEL_CLI_CMD " : rate limit set to %.2f", FLT_OTEL_CLI_MSG_CAT(msg), value);
+			} FLT_OTEL_PROXIES_LIST_END();
+		}
+	} else {
+		FLT_OTEL_PROXIES_LIST_START() {
+			uint32_t value = _HA_ATOMIC_LOAD(&(conf->instr->rate_limit));
+
+			(void)memprintf(&msg, "%s%s" FLT_OTEL_CLI_CMD " : current rate limit is %.2f", FLT_OTEL_CLI_MSG_CAT(msg), FLT_OTEL_U32_FLOAT(value));
+		} FLT_OTEL_PROXIES_LIST_END();
+	}
+
+	OTELC_RETURN_INT(flt_otel_cli_set_msg(appctx, err, msg));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_cli_parse_status - CLI status display handler
+ *
+ * SYNOPSIS
+ *   static int flt_otel_cli_parse_status(char **args, char *payload, struct appctx *appctx, void *private)
+ *
+ * ARGUMENTS
+ *   args    - CLI command arguments array
+ *   payload - CLI command payload string
+ *   appctx  - CLI application context
+ *   private - unused private data pointer
+ *
+ * DESCRIPTION
+ *   Handles the "otel status" CLI command.  Builds a formatted status report
+ *   for all OTel filter instances across all proxies.  The report includes
+ *   the library version, proxy name, configuration file path, group and scope
+ *   counts, disable counts, instrumentation ID, tracer and meter state, rate
+ *   limit, error mode, disabled state, logging state, and analyzer bits.  When
+ *   DEBUG_OTEL is enabled, the current debug level is also included.
+ *
+ * RETURN VALUE
+ *   Returns 1, or 0 on memory allocation failure.
+ */
+static int flt_otel_cli_parse_status(char **args, char *payload, struct appctx *appctx, void *private)
+{
+	const char *nl = "";
+	char       *msg = NULL;
+
+	OTELC_FUNC("%p, \"%s\", %p, %p", args, OTELC_STR_ARG(payload), appctx, private);
+
+	FLT_OTEL_ARGS_DUMP();
+	flt_otel_filters_dump();
+
+	(void)memprintf(&msg, " " FLT_OTEL_OPT_NAME " filter status\n" FLT_OTEL_STR_DASH_78 "\n");
+	(void)memprintf(&msg, "%s   library:       C++ " OTELCPP_VERSION ", C wrapper %s\n", msg, otelc_version());
+#ifdef DEBUG_OTEL
+	(void)memprintf(&msg, "%s   debug level:   0x%02hhx\n", msg, otelc_dbg_level);
+#endif
+	(void)memprintf(&msg, "%s   dropped count: %" PRId64 "/%" PRId64 " %" PRIu64 "\n", msg, otelc_processor_dropped_count(0), otelc_processor_dropped_count(1), _HA_ATOMIC_LOAD(&flt_otel_drop_cnt));
+
+	FLT_OTEL_PROXIES_LIST_START() {
+		struct flt_otel_conf_group *grp;
+		struct flt_otel_conf_scope *scp;
+		int                         n_groups = 0, n_scopes = 0;
+
+		list_for_each_entry(grp, &(conf->groups), list)
+			n_groups++;
+		list_for_each_entry(scp, &(conf->scopes), list)
+			n_scopes++;
+
+		(void)memprintf(&msg, "%s\n%s   proxy %s, filter %s\n", msg, nl, px->id, conf->id);
+		(void)memprintf(&msg, "%s     configuration: %s\n", msg, conf->cfg_file);
+		(void)memprintf(&msg, "%s     groups/scopes: %d/%d\n\n", msg, n_groups, n_scopes);
+		(void)memprintf(&msg, "%s       instrumentation %s\n", msg, conf->instr->id);
+		(void)memprintf(&msg, "%s       configuration: %s\n", msg, conf->instr->config);
+		(void)memprintf(&msg, "%s       tracer:        %s\n", msg, (conf->instr->tracer != NULL) ? "active" : "not initialized");
+		(void)memprintf(&msg, "%s       meter:         %s\n", msg, (conf->instr->meter != NULL) ? "active" : "not initialized");
+		(void)memprintf(&msg, "%s       logger:        %s\n", msg, (conf->instr->logger != NULL) ? "active" : "not initialized");
+		(void)memprintf(&msg, "%s       rate limit:    %.2f %%\n", msg, FLT_OTEL_U32_FLOAT(_HA_ATOMIC_LOAD(&(conf->instr->rate_limit))));
+		(void)memprintf(&msg, "%s       hard errors:   %s\n", msg, FLT_OTEL_STR_FLAG_YN(_HA_ATOMIC_LOAD(&(conf->instr->flag_harderr))));
+		(void)memprintf(&msg, "%s       disabled:      %s\n", msg, FLT_OTEL_STR_FLAG_YN(_HA_ATOMIC_LOAD(&(conf->instr->flag_disabled))));
+		(void)memprintf(&msg, "%s       logging:       %s\n", msg, FLT_OTEL_CLI_LOGGING_STATE(_HA_ATOMIC_LOAD(&(conf->instr->logging))));
+		(void)memprintf(&msg, "%s       analyzers:     %08x", msg, conf->instr->analyzers);
+#ifdef FLT_OTEL_USE_COUNTERS
+		(void)memprintf(&msg, "%s\n\n     counters\n", msg);
+		(void)memprintf(&msg, "%s       attached: %" PRIu64 " %" PRIu64 " %" PRIu64 " %" PRIu64 "\n", msg, conf->cnt.attached[0], conf->cnt.attached[1], conf->cnt.attached[2], conf->cnt.attached[3]);
+		(void)memprintf(&msg, "%s       disabled: %" PRIu64 " %" PRIu64, msg, conf->cnt.disabled[0], conf->cnt.disabled[1]);
+#endif
+
+		nl = "\n";
+	} FLT_OTEL_PROXIES_LIST_END();
+
+	OTELC_RETURN_INT(flt_otel_cli_set_msg(appctx, NULL, msg));
+}
+
+
+/* CLI command table for the OTel filter. */
+static struct cli_kw_list cli_kws = { { }, {
+#ifdef DEBUG_OTEL
+	{ { FLT_OTEL_CLI_CMD, "debug", NULL }, FLT_OTEL_CLI_CMD " debug [level]                  : set the OTEL filter debug level (default: get current debug level)", flt_otel_cli_parse_debug, NULL, NULL, NULL, ACCESS_LVL_ADMIN },
+#endif
+	{ { FLT_OTEL_CLI_CMD, "disable", NULL }, FLT_OTEL_CLI_CMD " disable                        : disable the OTEL filter", flt_otel_cli_parse_disabled, NULL, NULL, (void *)1, ACCESS_LVL_ADMIN },
+	{ { FLT_OTEL_CLI_CMD, "enable", NULL }, FLT_OTEL_CLI_CMD " enable                         : enable the OTEL filter", flt_otel_cli_parse_disabled, NULL, NULL, (void *)0, ACCESS_LVL_ADMIN },
+	{ { FLT_OTEL_CLI_CMD, "soft-errors", NULL }, FLT_OTEL_CLI_CMD " soft-errors                    : disable hard-errors mode", flt_otel_cli_parse_option, NULL, NULL, (void *)0, ACCESS_LVL_ADMIN },
+	{ { FLT_OTEL_CLI_CMD, "hard-errors", NULL }, FLT_OTEL_CLI_CMD " hard-errors                    : enable hard-errors mode", flt_otel_cli_parse_option, NULL, NULL, (void *)1, ACCESS_LVL_ADMIN },
+	{ { FLT_OTEL_CLI_CMD, "logging",  NULL }, FLT_OTEL_CLI_CMD " logging [state]                : set logging state (default: get current logging state)", flt_otel_cli_parse_logging, NULL, NULL, NULL, ACCESS_LVL_ADMIN },
+	{ { FLT_OTEL_CLI_CMD, "rate", NULL }, FLT_OTEL_CLI_CMD " rate [value]                   : set the rate limit (default: get current rate value)", flt_otel_cli_parse_rate, NULL, NULL, NULL, ACCESS_LVL_ADMIN },
+	{ { FLT_OTEL_CLI_CMD, "status", NULL }, FLT_OTEL_CLI_CMD " status                         : show the OTEL filter status", flt_otel_cli_parse_status, NULL, NULL, NULL, 0 },
+	{ /* END */ }
+}};
+
+
+/***
+ * NAME
+ *   flt_otel_cli_init - CLI keyword registration
+ *
+ * SYNOPSIS
+ *   void flt_otel_cli_init(void)
+ *
+ * ARGUMENTS
+ *   This function takes no arguments.
+ *
+ * DESCRIPTION
+ *   Registers the OTel filter CLI keywords with the HAProxy CLI subsystem.
+ *   The keywords include commands for enable/disable, error mode, logging,
+ *   rate limit, status display, and (when DEBUG_OTEL is defined) debug level
+ *   management.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_cli_init(void)
+{
+	OTELC_FUNC("");
+
+	/* Register CLI keywords. */
+	cli_register_kw(&cli_kws);
+
+	OTELC_RETURN();
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/conf.c

@@ -0,0 +1,885 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+/***
+ * NAME
+ *   flt_otel_conf_hdr_init - conf_hdr structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_hdr *flt_otel_conf_hdr_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_hdr structure.  The <id> string is
+ *   duplicated and stored as the header identifier.  If <head> is non-NULL,
+ *   the structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(hdr, id, )
+
+
+/***
+ * NAME
+ *   flt_otel_conf_hdr_free - conf_hdr structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_hdr_free(struct flt_otel_conf_hdr **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_hdr structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(hdr, id,
+	FLT_OTEL_DBG_CONF_HDR("- conf_hdr free ", *ptr, id);
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_str_init - conf_str structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_str *flt_otel_conf_str_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_str structure.  The <id> string is
+ *   duplicated and stored as the string value.  If <head> is non-NULL, the
+ *   structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(str, str, )
+
+
+/***
+ * NAME
+ *   flt_otel_conf_str_free - conf_str structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_str_free(struct flt_otel_conf_str **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_str structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(str, str,
+	FLT_OTEL_DBG_CONF_HDR("- conf_str free ", *ptr, str);
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_link_init - conf_link structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_link *flt_otel_conf_link_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_link structure for a span link
+ *   reference.  The <id> string is duplicated and stored as the linked
+ *   span name.  If <head> is non-NULL, the structure is appended to
+ *   the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(link, span, )
+
+
+/***
+ * NAME
+ *   flt_otel_conf_link_free - conf_link structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_link_free(struct flt_otel_conf_link **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_link structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(link, span,
+	FLT_OTEL_DBG_CONF_HDR("- conf_link free ", *ptr, span);
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_ph_init - conf_ph placeholder structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_ph *flt_otel_conf_ph_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_ph (placeholder) structure.  The <id>
+ *   string is duplicated and stored as the placeholder identifier.  If <head>
+ *   is non-NULL, the structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(ph, id, )
+
+
+/***
+ * NAME
+ *   flt_otel_conf_ph_free - conf_ph structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_ph_free(struct flt_otel_conf_ph **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_ph structure and its contents,
+ *   then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(ph, id,
+	FLT_OTEL_DBG_CONF_HDR("- conf_ph free ", *ptr, id);
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_sample_expr_init - conf_sample_expr structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_sample_expr *flt_otel_conf_sample_expr_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_sample_expr structure.  The <id> string is
+ *   duplicated and stored as the expression value.  If <head> is non-NULL, the
+ *   structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(sample_expr, fmt_expr, )
+
+
+/***
+ * NAME
+ *   flt_otel_conf_sample_expr_free - conf_sample_expr structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_sample_expr_free(struct flt_otel_conf_sample_expr **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_sample_expr structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(sample_expr, fmt_expr,
+	FLT_OTEL_DBG_CONF_SAMPLE_EXPR("- conf_sample_expr free ", *ptr);
+
+	release_sample_expr((*ptr)->expr);
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_sample_init - conf_sample structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_sample *flt_otel_conf_sample_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_sample structure.  The <id> string is
+ *   duplicated and stored as the sample key.  If <head> is non-NULL, the
+ *   structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(sample, key,
+	LIST_INIT(&(retptr->exprs));
+	lf_expr_init(&(retptr->lf_expr));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_sample_init_ex - extended sample initialization
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_sample *flt_otel_conf_sample_init_ex(const char **args, int idx, int n, const struct otelc_value *extra, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   args  - configuration line arguments array
+ *   idx   - position where sample value starts
+ *   n     - maximum number of arguments to concatenate (0 means all)
+ *   extra - optional extra data (event name or status code)
+ *   line  - configuration file line number
+ *   head  - list to append to (or NULL)
+ *   err   - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Creates and initializes a conf_sample structure with extended data.  Calls
+ *   flt_otel_conf_sample_init() with <args[idx - 1]> as the sample key to
+ *   create the base structure, copies <extra> data (event name string or status
+ *   code integer), concatenates the remaining arguments into the sample value
+ *   string, and counts the number of sample expressions.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+struct flt_otel_conf_sample *flt_otel_conf_sample_init_ex(const char **args, int idx, int n, const struct otelc_value *extra, int line, struct list *head, char **err)
+{
+	struct flt_otel_conf_sample *retptr = NULL;
+
+	OTELC_FUNC("%p, %d, %d, %p, %d, %p, %p:%p", args, idx, n, extra, line, head, OTELC_DPTR_ARGS(err));
+
+	OTELC_DBG_VALUE(DEBUG, "extra ", extra);
+
+	/* Ensure the sample value is present in the args[] array. */
+	if (flt_otel_args_count(args) <= idx) {
+		FLT_OTEL_ERR("'%s' : too few arguments", args[0]);
+
+		OTELC_RETURN_PTR(retptr);
+	}
+
+	/* The sample key is located at the idx location of the args[] field. */
+	retptr = flt_otel_conf_sample_init(args[idx - 1], line, head, err);
+	if (retptr == NULL)
+		OTELC_RETURN_PTR(retptr);
+
+	if ((extra == NULL) || (extra->u_type == OTELC_VALUE_NULL)) {
+		/*
+		 * Do nothing - sample extra data is not set or initialized,
+		 * which means it is not used.
+		 */
+	}
+	else if (extra->u_type == OTELC_VALUE_STRING) {
+		retptr->extra.u_type       = OTELC_VALUE_DATA;
+		retptr->extra.u.value_data = OTELC_STRDUP(extra->u.value_string);
+		if (retptr->extra.u.value_data == NULL) {
+			FLT_OTEL_ERR("out of memory");
+			flt_otel_conf_sample_free(&retptr);
+
+			OTELC_RETURN_PTR(retptr);
+		}
+	}
+	else if (extra->u_type == OTELC_VALUE_INT32) {
+		retptr->extra.u_type        = extra->u_type;
+		retptr->extra.u.value_int32 = extra->u.value_int32;
+	}
+	else {
+		FLT_OTEL_ERR("invalid sample extra data type: %d", extra->u_type);
+		flt_otel_conf_sample_free(&retptr);
+
+		OTELC_RETURN_PTR(retptr);
+	}
+
+	/* The sample value starts in the args[] array after the key. */
+	retptr->num_exprs = flt_otel_args_concat(args, idx, n, &(retptr->fmt_string));
+	if (retptr->num_exprs == FLT_OTEL_RET_ERROR) {
+		FLT_OTEL_ERR("out of memory");
+		flt_otel_conf_sample_free(&retptr);
+
+		OTELC_RETURN_PTR(retptr);
+	}
+
+	FLT_OTEL_DBG_CONF_SAMPLE("- conf_sample init ", retptr);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_conf_sample_free - conf_sample structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_sample_free(struct flt_otel_conf_sample **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_sample structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(sample, key,
+	FLT_OTEL_DBG_CONF_SAMPLE("- conf_sample free ", *ptr);
+
+	OTELC_SFREE((*ptr)->fmt_string);
+	if ((*ptr)->extra.u_type == OTELC_VALUE_DATA)
+		OTELC_SFREE((*ptr)->extra.u.value_data);
+	FLT_OTEL_LIST_DESTROY(sample_expr, &((*ptr)->exprs));
+	lf_expr_deinit(&((*ptr)->lf_expr));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_context_init - conf_context structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_context *flt_otel_conf_context_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_context structure.  The <id> string is
+ *   duplicated and stored as the context identifier.  If <head> is non-NULL,
+ *   the structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(context, id, )
+
+
+/***
+ * NAME
+ *   flt_otel_conf_context_free - conf_context structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_context_free(struct flt_otel_conf_context **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_context structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(context, id,
+	FLT_OTEL_DBG_CONF_HDR("- conf_context free ", *ptr, id);
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_span_init - conf_span structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_span *flt_otel_conf_span_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_span structure with empty lists for links,
+ *   attributes, events, baggages, and statuses.  The <id> string is duplicated
+ *   and stored as the span name.  If <head> is non-NULL, the structure is
+ *   appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(span, id,
+	LIST_INIT(&(retptr->links));
+	LIST_INIT(&(retptr->attributes));
+	LIST_INIT(&(retptr->events));
+	LIST_INIT(&(retptr->baggages));
+	LIST_INIT(&(retptr->statuses));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_span_free - conf_span structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_span_free(struct flt_otel_conf_span **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_span structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(span, id,
+	FLT_OTEL_DBG_CONF_HDR("- conf_span free ", *ptr, id);
+
+	OTELC_SFREE((*ptr)->ref_id);
+	OTELC_SFREE((*ptr)->ctx_id);
+	FLT_OTEL_LIST_DESTROY(link, &((*ptr)->links));
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->attributes));
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->events));
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->baggages));
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->statuses));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_instrument_init - conf_instrument structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_instrument *flt_otel_conf_instrument_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_instrument structure.  Sets the instrument
+ *   type and meter index to OTELC_METRIC_INSTRUMENT_UNSET and initializes the
+ *   samples and attributes lists.  The <id> string is duplicated and stored as
+ *   the instrument name.  If <head> is non-NULL, the structure is appended to
+ *   the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(instrument, id,
+	retptr->idx       = OTELC_METRIC_INSTRUMENT_UNSET;
+	retptr->type      = OTELC_METRIC_INSTRUMENT_UNSET;
+	retptr->aggr_type = OTELC_METRIC_AGGREGATION_UNSET;
+	LIST_INIT(&(retptr->samples));
+	LIST_INIT(&(retptr->attributes));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_instrument_free - conf_instrument structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_instrument_free(struct flt_otel_conf_instrument **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_instrument structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(instrument, id,
+	FLT_OTEL_DBG_CONF_INSTRUMENT("- conf_instrument free ", *ptr);
+
+	OTELC_SFREE((*ptr)->description);
+	OTELC_SFREE((*ptr)->unit);
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->samples));
+	OTELC_SFREE((*ptr)->bounds);
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->attributes));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_log_record_init - conf_log_record structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_log_record *flt_otel_conf_log_record_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_log_record structure.  Initializes the
+ *   attributes and sample expressions lists.  The <id> string is required by
+ *   the macro but is not used directly; the severity level is stored
+ *   separately.  If <head> is non-NULL, the structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(log_record, id,
+	LIST_INIT(&(retptr->attributes));
+	LIST_INIT(&(retptr->samples));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_log_record_free - conf_log_record structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_log_record_free(struct flt_otel_conf_log_record **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_log_record structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(log_record, id,
+	FLT_OTEL_DBG_CONF_LOG_RECORD("- conf_log_record free ", *ptr);
+
+	OTELC_SFREE((*ptr)->event_name);
+	OTELC_SFREE((*ptr)->span);
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->attributes));
+	FLT_OTEL_LIST_DESTROY(sample, &((*ptr)->samples));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_scope_init - conf_scope structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_scope *flt_otel_conf_scope_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_scope structure with empty lists for ACLs,
+ *   contexts, spans, spans_to_finish, and instruments.  The <id> string is
+ *   duplicated and stored as the scope name.  If <head> is non-NULL, the
+ *   structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(scope, id,
+	LIST_INIT(&(retptr->acls));
+	LIST_INIT(&(retptr->contexts));
+	LIST_INIT(&(retptr->spans));
+	LIST_INIT(&(retptr->spans_to_finish));
+	LIST_INIT(&(retptr->instruments));
+	LIST_INIT(&(retptr->log_records));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_scope_free - conf_scope structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_scope_free(struct flt_otel_conf_scope **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_scope structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(scope, id,
+	struct acl *acl;
+	struct acl *aclback;
+
+	FLT_OTEL_DBG_CONF_SCOPE("- conf_scope free ", *ptr);
+
+	list_for_each_entry_safe(acl, aclback, &((*ptr)->acls), list) {
+		prune_acl(acl);
+		FLT_OTEL_LIST_DEL(&(acl->list));
+		OTELC_SFREE(acl);
+	}
+	free_acl_cond((*ptr)->cond);
+	FLT_OTEL_LIST_DESTROY(context, &((*ptr)->contexts));
+	FLT_OTEL_LIST_DESTROY(span, &((*ptr)->spans));
+	FLT_OTEL_LIST_DESTROY(str, &((*ptr)->spans_to_finish));
+	FLT_OTEL_LIST_DESTROY(instrument, &((*ptr)->instruments));
+	FLT_OTEL_LIST_DESTROY(log_record, &((*ptr)->log_records));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_group_init - conf_group structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_group *flt_otel_conf_group_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_group structure with an empty placeholder
+ *   scope list.  The <id> string is duplicated and stored as the group name.
+ *   If <head> is non-NULL, the structure is appended to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(group, id,
+	LIST_INIT(&(retptr->ph_scopes));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_group_free - conf_group structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_group_free(struct flt_otel_conf_group **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_group structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(group, id,
+	FLT_OTEL_DBG_CONF_GROUP("- conf_group free ", *ptr);
+
+	FLT_OTEL_LIST_DESTROY(ph_scope, &((*ptr)->ph_scopes));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_instr_init - conf_instr structure allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf_instr *flt_otel_conf_instr_init(const char *id, int line, struct list *head, char **err)
+ *
+ * ARGUMENTS
+ *   id   - identifier string to duplicate
+ *   line - configuration file line number
+ *   head - list to append to (or NULL)
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a conf_instr (instrumentation) structure.  Sets
+ *   the default rate limit to 100%, initializes the proxy_log for logger
+ *   support, and creates empty lists for ACLs, placeholder groups, and
+ *   placeholder scopes.  The <id> string is duplicated and stored as the
+ *   instrumentation name.  If <head> is non-NULL, the structure is appended
+ *   to the list.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+FLT_OTEL_CONF_FUNC_INIT(instr, id,
+	retptr->rate_limit = FLT_OTEL_FLOAT_U32(100.0);
+	init_new_proxy(&(retptr->proxy_log));
+	LIST_INIT(&(retptr->acls));
+	LIST_INIT(&(retptr->ph_groups));
+	LIST_INIT(&(retptr->ph_scopes));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_instr_free - conf_instr structure deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_instr_free(struct flt_otel_conf_instr **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf_instr structure and its
+ *   contents, then removes it from the list of structures of that type.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+FLT_OTEL_CONF_FUNC_FREE(instr, id,
+	struct acl    *acl;
+	struct acl    *aclback;
+	struct logger *logger;
+	struct logger *loggerback;
+
+	FLT_OTEL_DBG_CONF_INSTR("- conf_instr free ", *ptr);
+
+	OTELC_SFREE((*ptr)->config);
+	OTELC_DBG(NOTICE, "- deleting acls list %s", flt_otel_list_dump(&((*ptr)->acls)));
+	list_for_each_entry_safe(acl, aclback, &((*ptr)->acls), list) {
+		prune_acl(acl);
+		FLT_OTEL_LIST_DEL(&(acl->list));
+		OTELC_SFREE(acl);
+	}
+	OTELC_DBG(NOTICE, "- deleting proxy_log.loggers list %s", flt_otel_list_dump(&((*ptr)->proxy_log.loggers)));
+	list_for_each_entry_safe(logger, loggerback, &((*ptr)->proxy_log.loggers), list) {
+		LIST_DELETE(&(logger->list));
+		ha_free(&logger);
+	}
+	FLT_OTEL_LIST_DESTROY(ph_group, &((*ptr)->ph_groups));
+	FLT_OTEL_LIST_DESTROY(ph_scope, &((*ptr)->ph_scopes));
+)
+
+
+/***
+ * NAME
+ *   flt_otel_conf_init - top-level filter configuration allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_conf *flt_otel_conf_init(struct proxy *px)
+ *
+ * ARGUMENTS
+ *   px - proxy instance to associate with
+ *
+ * DESCRIPTION
+ *   Allocates and initializes the top-level flt_otel_conf structure.  Stores
+ *   the <px> proxy reference and creates empty group and scope lists.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the initialized structure, or NULL on failure.
+ */
+struct flt_otel_conf *flt_otel_conf_init(struct proxy *px)
+{
+	struct flt_otel_conf *retptr;
+
+	OTELC_FUNC("%p", px);
+
+	retptr = OTELC_CALLOC(1, sizeof(*retptr));
+	if (retptr == NULL)
+		OTELC_RETURN_PTR(retptr);
+
+	retptr->proxy = px;
+	LIST_INIT(&(retptr->groups));
+	LIST_INIT(&(retptr->scopes));
+	LIST_INIT(&(retptr->smp_args));
+
+	FLT_OTEL_DBG_CONF("- conf init ", retptr);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_conf_free - top-level filter configuration deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_conf_free(struct flt_otel_conf **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - a pointer to the address of a structure
+ *
+ * DESCRIPTION
+ *   Deallocates memory used by the flt_otel_conf structure and its contents.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_conf_free(struct flt_otel_conf **ptr)
+{
+	struct arg_list *cur, *back;
+
+	OTELC_FUNC("%p:%p", OTELC_DPTR_ARGS(ptr));
+
+	if ((ptr == NULL) || (*ptr == NULL))
+		OTELC_RETURN();
+
+	FLT_OTEL_DBG_CONF("- conf free ", *ptr);
+
+	OTELC_SFREE((*ptr)->id);
+	OTELC_SFREE((*ptr)->cfg_file);
+	flt_otel_conf_instr_free(&((*ptr)->instr));
+	FLT_OTEL_LIST_DESTROY(group, &((*ptr)->groups));
+	FLT_OTEL_LIST_DESTROY(scope, &((*ptr)->scopes));
+	/* Free any unresolved OTEL sample fetch args (error path). */
+	list_for_each_entry_safe(cur, back, &((*ptr)->smp_args), list) {
+		LIST_DELETE(&(cur->list));
+		ha_free(&cur);
+	}
+	OTELC_SFREE_CLEAR(*ptr);
+
+	OTELC_RETURN();
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/event.c

@@ -0,0 +1,849 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+/* Event data table built from the X-macro list. */
+#define FLT_OTEL_EVENT_DEF(a,b,c,d,e,f)   { AN_##b##_##a, OTELC_STRINGIFY_ARG(AN_##b##_##a), SMP_OPT_DIR_##b, SMP_VAL_FE_##c, SMP_VAL_BE_##d, e, f },
+const struct flt_otel_event_data flt_otel_event_data[FLT_OTEL_EVENT_MAX] = { FLT_OTEL_EVENT_DEFINES };
+#undef FLT_OTEL_EVENT_DEF
+
+
+/***
+ * NAME
+ *   flt_otel_scope_run_instrument_record - metric instrument value recorder
+ *
+ * SYNOPSIS
+ *   static int flt_otel_scope_run_instrument_record(struct stream *s, uint dir, struct otelc_meter *meter, struct flt_otel_conf_instrument *instr_ref, struct flt_otel_conf_instrument *instr, char **err)
+ *
+ * ARGUMENTS
+ *   s         - the stream providing the sample context
+ *   dir       - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   meter     - the OTel meter instance
+ *   instr_ref - the create-form instrument providing samples and meter index
+ *   instr     - the update-form instrument providing per-scope attributes
+ *   err       - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Evaluates sample expressions from a create-form instrument and records
+ *   the resulting value via the <meter> API.  Each expression is evaluated
+ *   with sample_process(), converted to an otelc_value via
+ *   flt_otel_sample_to_value(), and recorded via
+ *   <meter>->update_instrument_kv_n().
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+static int flt_otel_scope_run_instrument_record(struct stream *s, uint dir, struct otelc_meter *meter, struct flt_otel_conf_instrument *instr_ref, struct flt_otel_conf_instrument *instr, char **err)
+{
+	struct flt_otel_conf_sample      *sample;
+	struct flt_otel_conf_sample_expr *expr;
+	struct sample                     smp;
+	struct otelc_value                value;
+	struct flt_otel_scope_data_kv     instr_attr;
+	int                               retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("%p, %u, %p, %p, %p, %p:%p", s, dir, meter, instr_ref, instr, OTELC_DPTR_ARGS(err));
+
+	/* Evaluate instrument attributes from sample expressions. */
+	(void)memset(&instr_attr, 0, sizeof(instr_attr));
+
+	list_for_each_entry(sample, &(instr->attributes), list) {
+		struct otelc_value attr_value;
+
+		OTELC_DBG(DEBUG, "adding instrument attribute '%s' -> '%s'", sample->key, sample->fmt_string);
+
+		if (flt_otel_sample_eval(s, dir, sample, true, &attr_value, err) == FLT_OTEL_RET_ERROR) {
+			retval = FLT_OTEL_RET_ERROR;
+
+			continue;
+		}
+
+		if (flt_otel_sample_add_kv(&instr_attr, sample->key, &attr_value) == FLT_OTEL_RET_ERROR) {
+			if (attr_value.u_type == OTELC_VALUE_DATA)
+				OTELC_SFREE(attr_value.u.value_data);
+
+			retval = FLT_OTEL_RET_ERROR;
+		}
+	}
+
+	/* The samples list always contains exactly one entry. */
+	sample = LIST_NEXT(&(instr_ref->samples), struct flt_otel_conf_sample *, list);
+
+	(void)memset(&smp, 0, sizeof(smp));
+
+	if (sample->lf_used) {
+		/*
+		 * Log-format path: evaluate into a temporary buffer and present
+		 * the result as a string sample.
+		 */
+		smp.data.u.str.area = OTELC_CALLOC(1, global.tune.bufsize);
+		if (smp.data.u.str.area == NULL) {
+			FLT_OTEL_ERR("out of memory");
+
+			otelc_kv_destroy(&(instr_attr.attr), instr_attr.cnt);
+
+			OTELC_RETURN_INT(FLT_OTEL_RET_ERROR);
+		}
+
+		smp.data.type       = SMP_T_STR;
+		smp.data.u.str.data = build_logline(s, smp.data.u.str.area, global.tune.bufsize, &(sample->lf_expr));
+	} else {
+		/* The expressions list always contains exactly one entry. */
+		expr = LIST_NEXT(&(sample->exprs), struct flt_otel_conf_sample_expr *, list);
+
+		FLT_OTEL_DBG_CONF_SAMPLE_EXPR("sample expression ", expr);
+
+		if (sample_process(s->be, s->sess, s, dir | SMP_OPT_FINAL, expr->expr, &smp) == NULL) {
+			OTELC_DBG(NOTICE, "WARNING: failed to fetch '%s'", expr->fmt_expr);
+
+			retval = FLT_OTEL_RET_ERROR;
+		}
+	}
+
+	if (retval == FLT_OTEL_RET_ERROR) {
+		/* Do nothing. */
+	}
+	else if (flt_otel_sample_to_value(sample->key, &(smp.data), &value, err) == FLT_OTEL_RET_ERROR) {
+		if (value.u_type == OTELC_VALUE_DATA)
+			OTELC_SFREE(value.u.value_data);
+
+		retval = FLT_OTEL_RET_ERROR;
+	}
+	else {
+		OTELC_DBG_VALUE(DEBUG, "value ", &value);
+
+		/*
+		 * Metric instruments expect numeric values (INT64 or DOUBLE).
+		 * Reject OTELC_VALUE_DATA since the meter cannot interpret
+		 * arbitrary string data as a numeric measurement.
+		 */
+		if (value.u_type == OTELC_VALUE_DATA) {
+			OTELC_DBG(NOTICE, "WARNING: non-numeric value type for instrument '%s'", instr_ref->id);
+
+			if (otelc_value_strtonum(&value, OTELC_VALUE_INT64) == OTELC_RET_ERROR) {
+				OTELC_SFREE(value.u.value_data);
+
+				retval = FLT_OTEL_RET_ERROR;
+			}
+		}
+
+		if (retval != FLT_OTEL_RET_ERROR)
+			if (OTELC_OPS(meter, update_instrument_kv_n, HA_ATOMIC_LOAD(&(instr_ref->idx)), &value, instr_attr.attr, instr_attr.cnt) == OTELC_RET_ERROR)
+				retval = FLT_OTEL_RET_ERROR;
+	}
+
+	otelc_kv_destroy(&(instr_attr.attr), instr_attr.cnt);
+
+	if (sample->lf_used)
+		OTELC_SFREE(smp.data.u.str.area);
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_run_instrument - metric instrument processor
+ *
+ * SYNOPSIS
+ *   static int flt_otel_scope_run_instrument(struct stream *s, uint dir, struct flt_otel_conf_scope *scope, struct otelc_meter *meter, char **err)
+ *
+ * ARGUMENTS
+ *   s     - the stream providing the sample context
+ *   dir   - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   scope - the scope configuration containing the instrument list
+ *   meter - the OTel meter instance
+ *   err   - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Processes all metric instruments configured in <scope>.  Runs in two
+ *   passes: the first pass lazily creates create-form instruments via <meter>
+ *   on first use, using HA_ATOMIC_CAS on the instrument index to guarantee
+ *   thread-safe one-time initialization.  The second pass iterates over
+ *   update-form instruments and records measurements via
+ *   flt_otel_scope_run_instrument_record().  Instruments whose index is still
+ *   negative (UNUSED or PENDING) are skipped, so that a concurrent creation by
+ *   another thread does not cause an invalid <meter> access.
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+static int flt_otel_scope_run_instrument(struct stream *s, uint dir, struct flt_otel_conf_scope *scope, struct otelc_meter *meter, char **err)
+{
+	struct flt_otel_conf_instrument *conf_instr;
+	int                              retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("%p, %u, %p, %p, %p:%p", s, dir, scope, meter, OTELC_DPTR_ARGS(err));
+
+	list_for_each_entry(conf_instr, &(scope->instruments), list) {
+		if (conf_instr->type == OTELC_METRIC_INSTRUMENT_UPDATE) {
+			/* Do nothing. */
+		}
+		else if (HA_ATOMIC_LOAD(&(conf_instr->idx)) == OTELC_METRIC_INSTRUMENT_UNSET) {
+			int64_t expected = OTELC_METRIC_INSTRUMENT_UNSET;
+			int     rc;
+
+			OTELC_DBG(DEBUG, "run instrument '%s' -> '%s'", scope->id, conf_instr->id);
+			FLT_OTEL_DBG_CONF_INSTRUMENT("", conf_instr);
+
+			/*
+			 * Create form: use this instrument directly.  Lazily
+			 * create the instrument on first use.  Use CAS to
+			 * ensure only one thread performs the creation in a
+			 * multi-threaded environment.
+			 */
+			if (!HA_ATOMIC_CAS(&(conf_instr->idx), &expected, OTELC_METRIC_INSTRUMENT_PENDING))
+				continue;
+
+			/*
+			 * The view must be created before the instrument,
+			 * otherwise bucket boundaries cannot be set.
+			 */
+			if ((conf_instr->bounds != NULL) && (conf_instr->bounds_num > 0))
+				if (OTELC_OPS(meter, add_view, conf_instr->id, conf_instr->description, conf_instr->id, conf_instr->unit, conf_instr->type, conf_instr->aggr_type, conf_instr->bounds, conf_instr->bounds_num) == OTELC_RET_ERROR)
+					OTELC_DBG(NOTICE, "WARNING: failed to add view for instrument '%s'", conf_instr->id);
+
+			rc = OTELC_OPS(meter, create_instrument, conf_instr->id, conf_instr->description, conf_instr->unit, conf_instr->type, NULL);
+			if (rc == OTELC_RET_ERROR) {
+				OTELC_DBG(NOTICE, "WARNING: failed to create instrument '%s'", conf_instr->id);
+
+				HA_ATOMIC_STORE(&(conf_instr->idx), OTELC_METRIC_INSTRUMENT_UNSET);
+
+				retval = FLT_OTEL_RET_ERROR;
+
+				continue;
+			} else {
+				HA_ATOMIC_STORE(&(conf_instr->idx), rc);
+			}
+		}
+	}
+
+	list_for_each_entry(conf_instr, &(scope->instruments), list)
+		if (conf_instr->type == OTELC_METRIC_INSTRUMENT_UPDATE) {
+			struct flt_otel_conf_instrument *instr = conf_instr->ref;
+
+			OTELC_DBG(DEBUG, "run instrument '%s' -> '%s'", scope->id, conf_instr->id);
+			FLT_OTEL_DBG_CONF_INSTRUMENT("", conf_instr);
+
+			/*
+			 * Update form: record a measurement using an existing
+			 * create-form instrument.
+			 */
+			if (instr == NULL) {
+				OTELC_DBG(NOTICE, "WARNING: invalid reference instrument '%s'", conf_instr->id);
+
+				retval = FLT_OTEL_RET_ERROR;
+			}
+			else if (HA_ATOMIC_LOAD(&(instr->idx)) < 0) {
+				OTELC_DBG(NOTICE, "WARNING: instrument '%s' not yet created, skipping", instr->id);
+			}
+			else if (flt_otel_scope_run_instrument_record(s, dir, meter, instr, conf_instr, err) == FLT_OTEL_RET_ERROR) {
+				retval = FLT_OTEL_RET_ERROR;
+			}
+		}
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_run_log_record - log record emitter
+ *
+ * SYNOPSIS
+ *   static int flt_otel_scope_run_log_record(struct stream *s, struct filter *f, uint dir, struct flt_otel_conf_scope *scope, struct otelc_logger *logger, const struct timespec *ts, char **err)
+ *
+ * ARGUMENTS
+ *   s      - the stream providing the sample context
+ *   f      - the filter instance
+ *   dir    - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   scope  - the scope configuration containing the log record list
+ *   logger - the OTel logger instance
+ *   ts     - the wall-clock timestamp for the log record
+ *   err    - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Processes all log records configured in <scope>.  For each record, checks
+ *   whether the logger is enabled for the configured severity, evaluates the
+ *   sample expressions into a body string, resolves the optional span reference
+ *   against the runtime context, and emits the log record via the logger's
+ *   log_span operation.
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+static int flt_otel_scope_run_log_record(struct stream *s, struct filter *f, uint dir, struct flt_otel_conf_scope *scope, struct otelc_logger *logger, const struct timespec *ts, char **err)
+{
+	struct flt_otel_conf_log_record *conf_log;
+	int                              retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("%p, %p, %u, %p, %p, %p, %p:%p", s, f, dir, scope, logger, ts, OTELC_DPTR_ARGS(err));
+
+	list_for_each_entry(conf_log, &(scope->log_records), list) {
+		struct flt_otel_conf_sample      *sample;
+		struct flt_otel_conf_sample_expr *expr;
+		struct sample                     smp;
+		struct otelc_span                *otel_span = NULL;
+		struct flt_otel_scope_data_kv     log_attr;
+		struct buffer                     buffer;
+		int                               rc;
+
+		OTELC_DBG(DEBUG, "run log-record '%s' -> '%s'", scope->id, conf_log->id);
+
+		/* Skip if the logger is not enabled for this severity. */
+		if (OTELC_OPS(logger, enabled, conf_log->severity) == 0)
+			continue;
+
+		/* Evaluate log record attributes from sample expressions. */
+		(void)memset(&log_attr, 0, sizeof(log_attr));
+
+		list_for_each_entry(sample, &(conf_log->attributes), list) {
+			struct otelc_value attr_value;
+
+			OTELC_DBG(DEBUG, "adding log-record attribute '%s' -> '%s'", sample->key, sample->fmt_string);
+
+			if (flt_otel_sample_eval(s, dir, sample, true, &attr_value, err) == FLT_OTEL_RET_ERROR) {
+				retval = FLT_OTEL_RET_ERROR;
+
+				continue;
+			}
+
+			if (flt_otel_sample_add_kv(&log_attr, sample->key, &attr_value) == FLT_OTEL_RET_ERROR) {
+				if (attr_value.u_type == OTELC_VALUE_DATA)
+					OTELC_SFREE(attr_value.u.value_data);
+
+				retval = FLT_OTEL_RET_ERROR;
+			}
+		}
+
+		/* The samples list has exactly one entry. */
+		sample = LIST_NEXT(&(conf_log->samples), typeof(sample), list);
+
+		(void)memset(&buffer, 0, sizeof(buffer));
+
+		if (sample->lf_used) {
+			/*
+			 * Log-format path: evaluate the log-format expression
+			 * into a dynamically allocated buffer.
+			 */
+			chunk_init(&buffer, OTELC_CALLOC(1, global.tune.bufsize), global.tune.bufsize);
+			if (buffer.area != NULL)
+				buffer.data = build_logline(s, buffer.area, buffer.size, &(sample->lf_expr));
+		} else {
+			/*
+			 * Bare sample expression path: evaluate each expression
+			 * and concatenate the results.
+			 */
+			list_for_each_entry(expr, &(sample->exprs), list) {
+				(void)memset(&smp, 0, sizeof(smp));
+
+				if (sample_process(s->be, s->sess, s, dir | SMP_OPT_FINAL, expr->expr, &smp) == NULL) {
+					OTELC_DBG(NOTICE, "WARNING: failed to fetch '%s'", expr->fmt_expr);
+
+					retval = FLT_OTEL_RET_ERROR;
+
+					break;
+				}
+
+				if (buffer.area == NULL) {
+					chunk_init(&buffer, OTELC_CALLOC(1, global.tune.bufsize), global.tune.bufsize);
+					if (buffer.area == NULL)
+						break;
+				}
+
+				rc = flt_otel_sample_to_str(&(smp.data), buffer.area + buffer.data, buffer.size - buffer.data, err);
+				if (rc == FLT_OTEL_RET_ERROR) {
+					retval = FLT_OTEL_RET_ERROR;
+
+					break;
+				}
+
+				buffer.data += rc;
+			}
+		}
+
+		if (buffer.area == NULL) {
+			FLT_OTEL_ERR("out of memory");
+
+			retval = FLT_OTEL_RET_ERROR;
+
+			otelc_kv_destroy(&(log_attr.attr), log_attr.cnt);
+
+			continue;
+		}
+
+		/*
+		 * If the log record references a span, resolve it against the
+		 * runtime context.  A missing span is not fatal -- the log
+		 * record is emitted without span correlation.
+		 */
+		if (conf_log->span != NULL) {
+			struct flt_otel_runtime_context *rt_ctx = FLT_OTEL_RT_CTX(f->ctx);
+			struct flt_otel_scope_span      *sc_span;
+
+			list_for_each_entry(sc_span, &(rt_ctx->spans), list)
+				if (strcmp(sc_span->id, conf_log->span) == 0) {
+					otel_span = sc_span->span;
+
+					break;
+				}
+
+			if (otel_span == NULL)
+				OTELC_DBG(NOTICE, "WARNING: cannot find span '%s' for log-record", conf_log->span);
+		}
+
+		if (OTELC_OPS(logger, log_span, conf_log->severity, conf_log->event_id, conf_log->event_name, otel_span, ts, log_attr.attr, log_attr.cnt, "%s", buffer.area) == OTELC_RET_ERROR)
+			retval = FLT_OTEL_RET_ERROR;
+
+		otelc_kv_destroy(&(log_attr.attr), log_attr.cnt);
+		OTELC_SFREE(buffer.area);
+	}
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_run_span - single span execution
+ *
+ * SYNOPSIS
+ *   static int flt_otel_scope_run_span(struct stream *s, struct filter *f, struct channel *chn, uint dir, struct flt_otel_scope_span *span, struct flt_otel_scope_data *data, const struct flt_otel_conf_span *conf_span, const struct timespec *ts_steady, const struct timespec *ts_system, char **err)
+ *
+ * ARGUMENTS
+ *   s         - the stream being processed
+ *   f         - the filter instance
+ *   chn       - the channel used for HTTP header injection
+ *   dir       - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   span      - the runtime scope span to execute
+ *   data      - the evaluated scope data (attributes, events, links, status)
+ *   conf_span - the span configuration
+ *   ts_steady - the monotonic timestamp for span creation
+ *   ts_system - the wall-clock timestamp for span events
+ *   err       - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Executes a single span: creates the OTel span on first call via the tracer,
+ *   adds links, baggage, attributes, events and status from <data>, then
+ *   injects the span context into HTTP headers or HAProxy variables if
+ *   configured in <conf_span>.
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+static int flt_otel_scope_run_span(struct stream *s, struct filter *f, struct channel *chn, uint dir, struct flt_otel_scope_span *span, struct flt_otel_scope_data *data, const struct flt_otel_conf_span *conf_span, const struct timespec *ts_steady, const struct timespec *ts_system, char **err)
+{
+	struct flt_otel_conf *conf = FLT_OTEL_CONF(f);
+	int                   retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("%p, %p, %p, %u, %p, %p, %p, %p, %p, %p:%p", s, f, chn, dir, span, data, conf_span, ts_steady, ts_system, OTELC_DPTR_ARGS(err));
+
+	if (span == NULL)
+		OTELC_RETURN_INT(retval);
+
+	/* Create the OTel span on first invocation. */
+	if (span->span == NULL) {
+		span->span = OTELC_OPS(conf->instr->tracer, start_span_with_options, span->id, span->ref_span, span->ref_ctx, ts_steady, ts_system, OTELC_SPAN_KIND_SERVER, NULL, 0);
+		if (span->span == NULL)
+			OTELC_RETURN_INT(FLT_OTEL_RET_ERROR);
+	}
+
+	/* Add all resolved span links to the current span. */
+	if (!LIST_ISEMPTY(&(data->links))) {
+		struct flt_otel_scope_data_link *link;
+
+		list_for_each_entry(link, &(data->links), list) {
+			OTELC_DBG(DEBUG, "adding link %p %p", link->span, link->context);
+
+			if (OTELC_OPS(span->span, add_link, link->span, link->context, NULL, 0) == -1)
+				retval = FLT_OTEL_RET_ERROR;
+		}
+	}
+
+	/* Set baggage key-value pairs on the span. */
+	if (data->baggage.attr != NULL)
+		if (OTELC_OPS(span->span, set_baggage_kv_n, data->baggage.attr, data->baggage.cnt) == -1)
+			retval = FLT_OTEL_RET_ERROR;
+
+	/* Set span attributes. */
+	if (data->attributes.attr != NULL)
+		if (OTELC_OPS(span->span, set_attribute_kv_n, data->attributes.attr, data->attributes.cnt) == -1)
+			retval = FLT_OTEL_RET_ERROR;
+
+	/* Add span events in reverse order. */
+	if (!LIST_ISEMPTY(&(data->events))) {
+		struct flt_otel_scope_data_event *event;
+
+		list_for_each_entry_rev(event, &(data->events), list)
+			if (OTELC_OPS(span->span, add_event_kv_n, event->name, ts_system, event->attr, event->cnt) == -1)
+				retval = FLT_OTEL_RET_ERROR;
+	}
+
+	/* Set span status code and description. */
+	if (data->status.description != NULL)
+		if (OTELC_OPS(span->span, set_status, data->status.code, data->status.description) == -1)
+			retval = FLT_OTEL_RET_ERROR;
+
+	/* Inject span context into HTTP headers and variables. */
+	if (conf_span->ctx_id != NULL) {
+		struct otelc_http_headers_writer  writer;
+		struct otelc_text_map            *text_map = NULL;
+
+		if (flt_otel_inject_http_headers(span->span, &writer) != FLT_OTEL_RET_ERROR) {
+			int i = 0;
+
+			if (conf_span->ctx_flags & (FLT_OTEL_CTX_USE_VARS | FLT_OTEL_CTX_USE_HEADERS)) {
+				for (text_map = &(writer.text_map); i < text_map->count; i++) {
+#ifdef USE_OTEL_VARS
+					if (!(conf_span->ctx_flags & FLT_OTEL_CTX_USE_VARS))
+						/* Do nothing. */;
+					else if (flt_otel_var_register(FLT_OTEL_VARS_SCOPE, conf_span->ctx_id, text_map->key[i], err) == FLT_OTEL_RET_ERROR)
+						retval = FLT_OTEL_RET_ERROR;
+					else if (flt_otel_var_set(s, FLT_OTEL_VARS_SCOPE, conf_span->ctx_id, text_map->key[i], text_map->value[i], dir, err) == FLT_OTEL_RET_ERROR)
+						retval = FLT_OTEL_RET_ERROR;
+#endif
+
+					if (!(conf_span->ctx_flags & FLT_OTEL_CTX_USE_HEADERS))
+						/* Do nothing. */;
+					else if (flt_otel_http_header_set(chn, conf_span->ctx_id, text_map->key[i], text_map->value[i], err) == FLT_OTEL_RET_ERROR)
+						retval = FLT_OTEL_RET_ERROR;
+				}
+			}
+
+			otelc_text_map_destroy(&text_map);
+		}
+	}
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_run - scope execution engine
+ *
+ * SYNOPSIS
+ *   int flt_otel_scope_run(struct stream *s, struct filter *f, struct channel *chn, struct flt_otel_conf_scope *conf_scope, const struct timespec *ts_steady, const struct timespec *ts_system, uint dir, char **err)
+ *
+ * ARGUMENTS
+ *   s          - the stream being processed
+ *   f          - the filter instance
+ *   chn        - the channel for context extraction and injection
+ *   conf_scope - the scope configuration to execute
+ *   ts_steady  - the monotonic timestamp, or NULL to use current time
+ *   ts_system  - the wall-clock timestamp, or NULL to use current time
+ *   dir        - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   err        - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Executes a complete scope: evaluates ACL conditions, extracts contexts
+ *   from HTTP headers or HAProxy variables, iterates over configured spans
+ *   (resolving links, evaluating sample expressions for attributes, events,
+ *   baggage and status), calls flt_otel_scope_run_span() for each, processes
+ *   metric instruments, emits log records, then marks and finishes completed
+ *   spans.
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+int flt_otel_scope_run(struct stream *s, struct filter *f, struct channel *chn, struct flt_otel_conf_scope *conf_scope, const struct timespec *ts_steady, const struct timespec *ts_system, uint dir, char **err)
+{
+	struct flt_otel_conf         *conf = FLT_OTEL_CONF(f);
+	struct flt_otel_conf_context *conf_ctx;
+	struct flt_otel_conf_span    *conf_span;
+	struct flt_otel_conf_str     *span_to_finish;
+	struct timespec               ts_now_steady, ts_now_system;
+	int                           retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("%p, %p, %p, %p, %p, %p, %u, %p:%p", s, f, chn, conf_scope, ts_steady, ts_system, dir, OTELC_DPTR_ARGS(err));
+
+	OTELC_DBG(DEBUG, "channel: %s, mode: %s (%s)", flt_otel_chn_label(chn), flt_otel_pr_mode(s), flt_otel_stream_pos(s));
+	OTELC_DBG(DEBUG, "run scope '%s' %d", conf_scope->id, conf_scope->event);
+	FLT_OTEL_DBG_CONF_SCOPE("run scope ", conf_scope);
+
+	if (ts_steady == NULL) {
+		(void)clock_gettime(CLOCK_MONOTONIC, &ts_now_steady);
+
+		ts_steady = &ts_now_steady;
+	}
+	if (ts_system == NULL) {
+		(void)clock_gettime(CLOCK_REALTIME, &ts_now_system);
+
+		ts_system = &ts_now_system;
+	}
+
+	/* Evaluate the scope's ACL condition; skip this scope on mismatch. */
+	if (conf_scope->cond != NULL) {
+		enum acl_test_res res;
+		int               rc;
+
+		res = acl_exec_cond(conf_scope->cond, s->be, s->sess, s, dir | SMP_OPT_FINAL);
+		rc  = acl_pass(res);
+		if (conf_scope->cond->pol == ACL_COND_UNLESS)
+			rc = !rc;
+
+		OTELC_DBG(DEBUG, "the ACL rule %s", rc ? "matches" : "does not match");
+
+		/*
+		 * If the rule does not match, the current scope is skipped.
+		 *
+		 * If it is a root span, further processing of the session is
+		 * disabled.  As soon as the first span is encountered which
+		 * is marked as root, further search is interrupted.
+		 */
+		if (rc == 0) {
+			list_for_each_entry(conf_span, &(conf_scope->spans), list)
+				if (conf_span->flag_root) {
+					OTELC_DBG(LOG, "session disabled");
+
+					FLT_OTEL_RT_CTX(f->ctx)->flag_disabled = 1;
+
+#ifdef FLT_OTEL_USE_COUNTERS
+					_HA_ATOMIC_ADD(conf->cnt.disabled + 0, 1);
+#endif
+
+					break;
+				}
+
+			OTELC_RETURN_INT(retval);
+		}
+	}
+
+	/* Extract and initialize OpenTelemetry propagation contexts. */
+	list_for_each_entry(conf_ctx, &(conf_scope->contexts), list) {
+		struct otelc_text_map *text_map = NULL;
+
+		OTELC_DBG(DEBUG, "run context '%s' -> '%s'", conf_scope->id, conf_ctx->id);
+		FLT_OTEL_DBG_CONF_CONTEXT("run context ", conf_ctx);
+
+		/*
+		 * The OpenTelemetry context is read from the HTTP header
+		 * or from HAProxy variables.
+		 */
+		if (conf_ctx->flags & FLT_OTEL_CTX_USE_HEADERS)
+			text_map = flt_otel_http_headers_get(chn, conf_ctx->id, conf_ctx->id_len, err);
+#ifdef USE_OTEL_VARS
+		else
+			text_map = flt_otel_vars_get(s, FLT_OTEL_VARS_SCOPE, conf_ctx->id, dir, err);
+#endif
+
+		if (text_map != NULL) {
+			if (flt_otel_scope_context_init(f->ctx, conf->instr->tracer, conf_ctx->id, conf_ctx->id_len, text_map, dir, err) == NULL)
+				retval = FLT_OTEL_RET_ERROR;
+
+			otelc_text_map_destroy(&text_map);
+		} else {
+			retval = FLT_OTEL_RET_ERROR;
+		}
+	}
+
+	/* Process configured spans: resolve links and collect samples. */
+	list_for_each_entry(conf_span, &(conf_scope->spans), list) {
+		struct flt_otel_scope_data   data;
+		struct flt_otel_scope_span  *span;
+		struct flt_otel_conf_sample *sample;
+
+		OTELC_DBG(DEBUG, "run span '%s' -> '%s'", conf_scope->id, conf_span->id);
+		FLT_OTEL_DBG_CONF_SPAN("run span ", conf_span);
+
+		flt_otel_scope_data_init(&data);
+
+		span = flt_otel_scope_span_init(f->ctx, conf_span->id, conf_span->id_len, conf_span->ref_id, conf_span->ref_id_len, dir, err);
+		if (span == NULL)
+			retval = FLT_OTEL_RET_ERROR;
+
+		/*
+		 * Resolve configured span links against the runtime context.
+		 * Each link name is looked up first in the active spans, then
+		 * in the extracted contexts.
+		 */
+		if (!LIST_ISEMPTY(&(conf_span->links))) {
+			struct flt_otel_runtime_context *rt_ctx = FLT_OTEL_RT_CTX(f->ctx);
+			struct flt_otel_conf_link       *conf_link;
+
+			list_for_each_entry(conf_link, &(conf_span->links), list) {
+				struct flt_otel_scope_data_link *data_link;
+				struct otelc_span               *link_span = NULL;
+				struct otelc_span_context       *link_ctx = NULL;
+				struct flt_otel_scope_span      *sc_span;
+				struct flt_otel_scope_context   *sc_ctx;
+
+				/* Try to find a matching span first. */
+				list_for_each_entry(sc_span, &(rt_ctx->spans), list)
+					if (FLT_OTEL_CONF_STR_CMP(sc_span->id, conf_link->span)) {
+						link_span = sc_span->span;
+
+						break;
+					}
+
+				/* If no span found, try to find a matching context. */
+				if (link_span == NULL) {
+					list_for_each_entry(sc_ctx, &(rt_ctx->contexts), list)
+						if (FLT_OTEL_CONF_STR_CMP(sc_ctx->id, conf_link->span)) {
+							link_ctx = sc_ctx->context;
+
+							break;
+						}
+				}
+
+				if ((link_span == NULL) && (link_ctx == NULL)) {
+					OTELC_DBG(NOTICE, "WARNING: cannot find linked span/context '%s'", conf_link->span);
+
+					continue;
+				}
+
+				data_link = OTELC_CALLOC(1, sizeof(*data_link));
+				if (data_link == NULL) {
+					retval = FLT_OTEL_RET_ERROR;
+
+					break;
+				}
+
+				data_link->span    = link_span;
+				data_link->context = link_ctx;
+				LIST_APPEND(&(data.links), &(data_link->list));
+
+				OTELC_DBG(DEBUG, "resolved link '%s' -> %p %p", conf_link->span, link_span, link_ctx);
+			}
+		}
+
+		list_for_each_entry(sample, &(conf_span->attributes), list) {
+			OTELC_DBG(DEBUG, "adding attribute '%s' -> '%s'", sample->key, sample->fmt_string);
+
+			if (flt_otel_sample_add(s, dir, sample, &data, FLT_OTEL_EVENT_SAMPLE_ATTRIBUTE, err) == FLT_OTEL_RET_ERROR)
+				retval = FLT_OTEL_RET_ERROR;
+		}
+
+		list_for_each_entry(sample, &(conf_span->events), list) {
+			OTELC_DBG(DEBUG, "adding event '%s' -> '%s'", sample->key, sample->fmt_string);
+
+			if (flt_otel_sample_add(s, dir, sample, &data, FLT_OTEL_EVENT_SAMPLE_EVENT, err) == FLT_OTEL_RET_ERROR)
+				retval = FLT_OTEL_RET_ERROR;
+		}
+
+		list_for_each_entry(sample, &(conf_span->baggages), list) {
+			OTELC_DBG(DEBUG, "adding baggage '%s' -> '%s'", sample->key, sample->fmt_string);
+
+			if (flt_otel_sample_add(s, dir, sample, &data, FLT_OTEL_EVENT_SAMPLE_BAGGAGE, err) == FLT_OTEL_RET_ERROR)
+				retval = FLT_OTEL_RET_ERROR;
+		}
+
+		/*
+		 * Regardless of the use of the list, only one status per event
+		 * is allowed.
+		 */
+		list_for_each_entry(sample, &(conf_span->statuses), list) {
+			OTELC_DBG(DEBUG, "adding status '%s' -> '%s'", sample->key, sample->fmt_string);
+
+			if (flt_otel_sample_add(s, dir, sample, &data, FLT_OTEL_EVENT_SAMPLE_STATUS, err) == FLT_OTEL_RET_ERROR)
+				retval = FLT_OTEL_RET_ERROR;
+		}
+
+		/* Attempt to run the span regardless of earlier errors. */
+		if (span != NULL)
+			if (flt_otel_scope_run_span(s, f, chn, dir, span, &data, conf_span, ts_steady, ts_system, err) == FLT_OTEL_RET_ERROR)
+				retval = FLT_OTEL_RET_ERROR;
+
+		flt_otel_scope_data_free(&data);
+	}
+
+	/* Process metric instruments. */
+	if (!LIST_ISEMPTY(&(conf_scope->instruments)))
+		if (flt_otel_scope_run_instrument(s, dir, conf_scope, conf->instr->meter, err) == FLT_OTEL_RET_ERROR)
+			retval = FLT_OTEL_RET_ERROR;
+
+	/* Emit log records. */
+	if (!LIST_ISEMPTY(&(conf_scope->log_records)))
+		if (flt_otel_scope_run_log_record(s, f, dir, conf_scope, conf->instr->logger, ts_system, err) == FLT_OTEL_RET_ERROR)
+			retval = FLT_OTEL_RET_ERROR;
+
+	/* Mark the configured spans for finishing and clean up. */
+	list_for_each_entry(span_to_finish, &(conf_scope->spans_to_finish), list)
+		if (flt_otel_scope_finish_mark(f->ctx, span_to_finish->str, span_to_finish->str_len) == FLT_OTEL_RET_ERROR)
+			retval = FLT_OTEL_RET_ERROR;
+
+	flt_otel_scope_finish_marked(f->ctx, ts_steady);
+	flt_otel_scope_free_unused(f->ctx, chn);
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_event_run - top-level event dispatcher
+ *
+ * SYNOPSIS
+ *   int flt_otel_event_run(struct stream *s, struct filter *f, struct channel *chn, int event, char **err)
+ *
+ * ARGUMENTS
+ *   s     - the stream being processed
+ *   f     - the filter instance
+ *   chn   - the channel being analyzed
+ *   event - the event index (FLT_OTEL_EVENT_*)
+ *   err   - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Top-level event dispatcher called from filter callbacks.  It iterates over
+ *   all scopes matching the <event> index and calls flt_otel_scope_run() for
+ *   each.  All spans within a single event share the same monotonic and
+ *   wall-clock timestamps.
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+int flt_otel_event_run(struct stream *s, struct filter *f, struct channel *chn, int event, char **err)
+{
+	struct flt_otel_conf       *conf = FLT_OTEL_CONF(f);
+	struct flt_otel_conf_scope *conf_scope;
+	struct timespec             ts_steady, ts_system;
+	int                         retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("%p, %p, %p, %d, %p:%p", s, f, chn, event, OTELC_DPTR_ARGS(err));
+
+	OTELC_DBG(DEBUG, "channel: %s, mode: %s (%s)", flt_otel_chn_label(chn), flt_otel_pr_mode(s), flt_otel_stream_pos(s));
+	OTELC_DBG(DEBUG, "run event '%s' %d %s", flt_otel_event_data[event].name, event, flt_otel_event_data[event].an_name);
+
+#ifdef DEBUG_OTEL
+	_HA_ATOMIC_ADD(conf->cnt.event[event].htx + ((chn == NULL) ? 1 : (htx_is_empty(htxbuf(&(chn->buf))) ? 1 : 0)), 1);
+#endif
+
+	FLT_OTEL_RT_CTX(f->ctx)->analyzers |= flt_otel_event_data[event].an_bit;
+
+	/* All spans should be created/completed at the same time. */
+	(void)clock_gettime(CLOCK_MONOTONIC, &ts_steady);
+	(void)clock_gettime(CLOCK_REALTIME, &ts_system);
+
+	/*
+	 * It is possible that there are defined multiple scopes that use the
+	 * same event.  Therefore, there must not be a 'break' here, ie an exit
+	 * from the 'for' loop.
+	 */
+	list_for_each_entry(conf_scope, &(conf->scopes), list) {
+		if (conf_scope->event != event)
+			/* Do nothing. */;
+		else if (!conf_scope->flag_used)
+			OTELC_DBG(DEBUG, "scope '%s' %d not used", conf_scope->id, conf_scope->event);
+		else if (flt_otel_scope_run(s, f, chn, conf_scope, &ts_steady, &ts_system, flt_otel_event_data[event].smp_opt_dir, err) == FLT_OTEL_RET_ERROR)
+			retval = FLT_OTEL_RET_ERROR;
+	}
+
+#ifdef USE_OTEL_VARS
+	flt_otel_vars_dump(s);
+#endif
+	flt_otel_http_headers_dump(chn);
+
+	OTELC_DBG(DEBUG, "event = %d %s, chn = %p, s->req = %p, s->res = %p", event, flt_otel_event_data[event].an_name, chn, &(s->req), &(s->res));
+
+	OTELC_RETURN_INT(retval);
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/group.c

@@ -0,0 +1,378 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+/* Group data table built from the X-macro list. */
+#define FLT_OTEL_GROUP_DEF(a,b,c)   { a, b, c },
+const struct flt_otel_group_data flt_otel_group_data[] = { FLT_OTEL_GROUP_DEFINES };
+#undef FLT_OTEL_GROUP_DEF
+
+
+/***
+ * NAME
+ *   flt_otel_group_action - group action execution callback
+ *
+ * SYNOPSIS
+ *   static enum act_return flt_otel_group_action(struct act_rule *rule, struct proxy *px, struct session *sess, struct stream *s, int opts)
+ *
+ * ARGUMENTS
+ *   rule - action rule containing group configuration references
+ *   px   - proxy instance
+ *   sess - current session
+ *   s    - current stream
+ *   opts - action options (ACT_OPT_* flags)
+ *
+ * DESCRIPTION
+ *   Executes the action_ptr callback for the FLT_OTEL_ACTION_GROUP action.
+ *   Retrieves the filter configuration, group definition, and runtime context
+ *   from the rule's argument pointers.  If the filter is disabled or not
+ *   attached to the stream, processing is skipped.  Otherwise, iterates over
+ *   all scopes defined in the group and runs each via flt_otel_scope_run().
+ *   Scope execution errors are logged but do not prevent the remaining scopes
+ *   from executing.
+ *
+ * RETURN VALUE
+ *   Returns ACT_RET_CONT.
+ */
+static enum act_return flt_otel_group_action(struct act_rule *rule, struct proxy *px, struct session *sess, struct stream *s, int opts)
+{
+	const struct filter                   *filter;
+	const struct flt_conf                 *fconf;
+	const struct flt_otel_conf            *conf;
+	const struct flt_otel_conf_group      *conf_group;
+	const struct flt_otel_runtime_context *rt_ctx = NULL;
+	const struct flt_otel_conf_ph         *ph_scope;
+	char                                  *err = NULL;
+	int                                    i, rc;
+
+	OTELC_FUNC("%p, %p, %p, %p, %d", rule, px, sess, s, opts);
+
+	OTELC_DBG(DEBUG, "from: %d, arg.act %p:{ %p %p %p %p }", rule->from, &(rule->arg.act), rule->arg.act.p[0], rule->arg.act.p[1], rule->arg.act.p[2], rule->arg.act.p[3]);
+
+	fconf      = rule->arg.act.p[FLT_OTEL_ARG_FLT_CONF];
+	conf       = rule->arg.act.p[FLT_OTEL_ARG_CONF];
+	conf_group = ((const struct flt_otel_conf_ph *)(rule->arg.act.p[FLT_OTEL_ARG_GROUP]))->ptr;
+
+	if ((fconf == NULL) || (conf == NULL) || (conf_group == NULL)) {
+		FLT_OTEL_LOG(LOG_ERR, FLT_OTEL_ACTION_GROUP ": internal error, invalid group action");
+
+		OTELC_RETURN_EX(ACT_RET_CONT, enum act_return, "%d");
+	}
+
+	if (_HA_ATOMIC_LOAD(&(conf->instr->flag_disabled))) {
+		OTELC_DBG(INFO, "filter '%s' disabled, group action '%s' ignored", conf->id, conf_group->id);
+
+		OTELC_RETURN_EX(ACT_RET_CONT, enum act_return, "%d");
+	}
+
+	/* Find the OpenTelemetry filter instance from the current stream. */
+	list_for_each_entry(filter, &(s->strm_flt.filters), list)
+		if (filter->config == fconf) {
+			rt_ctx = filter->ctx;
+
+			break;
+		}
+
+	if (rt_ctx == NULL) {
+		OTELC_DBG(INFO, "cannot find filter, probably not attached to the stream");
+
+		OTELC_RETURN_EX(ACT_RET_CONT, enum act_return, "%d");
+	}
+	else if (flt_otel_is_disabled(filter FLT_OTEL_DBG_ARGS(, -1))) {
+		OTELC_RETURN_EX(ACT_RET_CONT, enum act_return, "%d");
+	}
+	else {
+		OTELC_DBG(DEBUG, "run group '%s'", conf_group->id);
+		FLT_OTEL_DBG_CONF_GROUP("run group ", conf_group);
+	}
+
+	/*
+	 * Check the value of rule->from; in case it is incorrect,
+	 * report an error.
+	 */
+	for (i = 0; i < OTELC_TABLESIZE(flt_otel_group_data); i++)
+		if (flt_otel_group_data[i].act_from == rule->from)
+			break;
+
+	if (i >= OTELC_TABLESIZE(flt_otel_group_data)) {
+		FLT_OTEL_LOG(LOG_ERR, FLT_OTEL_ACTION_GROUP ": internal error, invalid rule->from=%d", rule->from);
+
+		OTELC_RETURN_EX(ACT_RET_CONT, enum act_return, "%d");
+	}
+
+	/* Execute each scope defined in this group. */
+	list_for_each_entry(ph_scope, &(conf_group->ph_scopes), list) {
+		rc = flt_otel_scope_run(s, rt_ctx->filter, (flt_otel_group_data[i].smp_opt_dir == SMP_OPT_DIR_REQ) ? &(s->req) : &(s->res), ph_scope->ptr, NULL, NULL, flt_otel_group_data[i].smp_opt_dir, &err);
+		if ((rc == FLT_OTEL_RET_ERROR) && (opts & ACT_OPT_FINAL)) {
+			FLT_OTEL_LOG(LOG_ERR, FLT_OTEL_ACTION_GROUP ": scope '%s' failed in group '%s'", ph_scope->id, conf_group->id);
+			OTELC_SFREE_CLEAR(err);
+		}
+	}
+
+	OTELC_RETURN_EX(ACT_RET_CONT, enum act_return, "%d");
+}
+
+
+/***
+ * NAME
+ *   flt_otel_group_check - group action post-parse check callback
+ *
+ * SYNOPSIS
+ *   static int flt_otel_group_check(struct act_rule *rule, struct proxy *px, char **err)
+ *
+ * ARGUMENTS
+ *   rule - action rule to validate
+ *   px   - proxy instance
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Validates the check_ptr callback for the FLT_OTEL_ACTION_GROUP action.
+ *   Resolves the filter ID and group ID string references stored during parsing
+ *   into direct pointers to the filter configuration and group configuration
+ *   structures.  Searches the proxy's filter list for a matching OTel filter,
+ *   then locates the named group within that filter's configuration.  On
+ *   success, replaces the string ID pointers in <rule>->arg.act.p with the
+ *   resolved configuration pointers.
+ *
+ * RETURN VALUE
+ *   Returns 1 on success, or 0 on failure with <err> filled.
+ */
+static int flt_otel_group_check(struct act_rule *rule, struct proxy *px, char **err)
+{
+	struct flt_conf         *fconf_tmp, *fconf = NULL;
+	struct flt_otel_conf    *conf;
+	struct flt_otel_conf_ph *ph_group;
+	const char              *filter_id;
+	const char              *group_id;
+	bool                     flag_found = 0;
+	int                      i;
+
+	OTELC_FUNC("%p, %p, %p:%p", rule, px, OTELC_DPTR_ARGS(err));
+
+	filter_id = rule->arg.act.p[FLT_OTEL_ARG_FILTER_ID];
+	group_id  = rule->arg.act.p[FLT_OTEL_ARG_GROUP_ID];
+
+	OTELC_DBG(NOTICE, "checking filter_id='%s', group_id='%s'", filter_id, group_id);
+
+	/*
+	 * Check the value of rule->from; in case it is incorrect, report an
+	 * error.
+	 */
+	for (i = 0; i < OTELC_TABLESIZE(flt_otel_group_data); i++)
+		if (flt_otel_group_data[i].act_from == rule->from)
+			break;
+
+	if (i >= OTELC_TABLESIZE(flt_otel_group_data)) {
+		FLT_OTEL_ERR("internal error, unexpected rule->from=%d, please report this bug!", rule->from);
+
+		OTELC_RETURN_INT(0);
+	}
+
+	/*
+	 * Try to find the OpenTelemetry filter by checking all filters for the
+	 * proxy <px>.
+	 */
+	list_for_each_entry(fconf_tmp, &(px->filter_configs), list) {
+		conf = fconf_tmp->conf;
+
+		if (fconf_tmp->id != otel_flt_id) {
+			/* This is not an OpenTelemetry filter. */
+			continue;
+		}
+		else if (strcmp(conf->id, filter_id) == 0) {
+			/* This is the good filter ID. */
+			fconf = fconf_tmp;
+
+			break;
+		}
+	}
+
+	if (fconf == NULL) {
+		FLT_OTEL_ERR("unable to find the OpenTelemetry filter '%s' used by the " FLT_OTEL_ACTION_GROUP " '%s'", filter_id, group_id);
+
+		OTELC_RETURN_INT(0);
+	}
+
+	/*
+	 * Attempt to find if the group is defined in the OpenTelemetry filter
+	 * configuration.
+	 */
+	list_for_each_entry(ph_group, &(conf->instr->ph_groups), list)
+		if (strcmp(ph_group->id, group_id) == 0) {
+			flag_found = 1;
+
+			break;
+		}
+
+	if (!flag_found) {
+		FLT_OTEL_ERR("unable to find group '%s' in the OpenTelemetry filter '%s' configuration", group_id, filter_id);
+
+		OTELC_RETURN_INT(0);
+	}
+
+	OTELC_SFREE_CLEAR(rule->arg.act.p[FLT_OTEL_ARG_FILTER_ID]);
+	OTELC_SFREE_CLEAR(rule->arg.act.p[FLT_OTEL_ARG_GROUP_ID]);
+
+	/* Replace string IDs with resolved configuration pointers. */
+	rule->arg.act.p[FLT_OTEL_ARG_FLT_CONF] = fconf;
+	rule->arg.act.p[FLT_OTEL_ARG_CONF]     = conf;
+	rule->arg.act.p[FLT_OTEL_ARG_GROUP]    = ph_group;
+
+	OTELC_RETURN_INT(1);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_group_release - group action release callback
+ *
+ * SYNOPSIS
+ *   static void flt_otel_group_release(struct act_rule *rule)
+ *
+ * ARGUMENTS
+ *   rule - action rule being released
+ *
+ * DESCRIPTION
+ *   Provides the release_ptr callback for the FLT_OTEL_ACTION_GROUP action.
+ *   This is a no-op because the group action's argument pointers reference
+ *   shared configuration structures that are freed separately during filter
+ *   deinitialization.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+static void flt_otel_group_release(struct act_rule *rule)
+{
+	OTELC_FUNC("%p", rule);
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_group_parse - group action keyword parser
+ *
+ * SYNOPSIS
+ *   static enum act_parse_ret flt_otel_group_parse(const char **args, int *cur_arg, struct proxy *px, struct act_rule *rule, char **err)
+ *
+ * ARGUMENTS
+ *   args    - configuration line arguments array
+ *   cur_arg - pointer to the current argument index
+ *   px      - proxy instance
+ *   rule    - action rule to populate
+ *   err     - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Parses the FLT_OTEL_ACTION_GROUP action keyword from HAProxy configuration
+ *   rules.  Expects two arguments: a filter ID and a group ID, optionally
+ *   followed by "if" or "unless" conditions.  The filter ID and group ID are
+ *   duplicated and stored in the <rule>'s argument pointers for later
+ *   resolution by flt_otel_group_check().  The <rule>'s callbacks are set to
+ *   flt_otel_group_action(), flt_otel_group_check(), and
+ *   flt_otel_group_release().  This parser is registered for tcp-request,
+ *   tcp-response, http-request, http-response, and http-after-response action
+ *   contexts.
+ *
+ * RETURN VALUE
+ *   Returns ACT_RET_PRS_OK on success, or ACT_RET_PRS_ERR on failure.
+ */
+static enum act_parse_ret flt_otel_group_parse(const char **args, int *cur_arg, struct proxy *px, struct act_rule *rule, char **err)
+{
+	OTELC_FUNC("%p, %p, %p, %p, %p:%p", args, cur_arg, px, rule, OTELC_DPTR_ARGS(err));
+
+	FLT_OTEL_ARGS_DUMP();
+
+	if (!FLT_OTEL_ARG_ISVALID(*cur_arg) || !FLT_OTEL_ARG_ISVALID(*cur_arg + 1) ||
+	    (FLT_OTEL_ARG_ISVALID(*cur_arg + 2) &&
+	     !FLT_OTEL_PARSE_KEYWORD(*cur_arg + 2, FLT_OTEL_CONDITION_IF) &&
+	     !FLT_OTEL_PARSE_KEYWORD(*cur_arg + 2, FLT_OTEL_CONDITION_UNLESS))) {
+		FLT_OTEL_ERR("expects: <filter-id> <group-id> [{ if | unless } ...]");
+
+		OTELC_RETURN_EX(ACT_RET_PRS_ERR, enum act_parse_ret, "%d");
+	}
+
+	/* Copy the OpenTelemetry filter id. */
+	rule->arg.act.p[FLT_OTEL_ARG_FILTER_ID] = OTELC_STRDUP(args[*cur_arg]);
+	if (rule->arg.act.p[FLT_OTEL_ARG_FILTER_ID] == NULL) {
+		FLT_OTEL_ERR("%s : out of memory", args[*cur_arg]);
+
+		OTELC_RETURN_EX(ACT_RET_PRS_ERR, enum act_parse_ret, "%d");
+	}
+
+	/* Copy the OpenTelemetry group id. */
+	rule->arg.act.p[FLT_OTEL_ARG_GROUP_ID] = OTELC_STRDUP(args[*cur_arg + 1]);
+	if (rule->arg.act.p[FLT_OTEL_ARG_GROUP_ID] == NULL) {
+		FLT_OTEL_ERR("%s : out of memory", args[*cur_arg + 1]);
+
+		OTELC_SFREE_CLEAR(rule->arg.act.p[FLT_OTEL_ARG_FILTER_ID]);
+
+		OTELC_RETURN_EX(ACT_RET_PRS_ERR, enum act_parse_ret, "%d");
+	}
+
+	/* Wire up the rule callbacks. */
+	rule->action      = ACT_CUSTOM;
+	rule->action_ptr  = flt_otel_group_action;
+	rule->check_ptr   = flt_otel_group_check;
+	rule->release_ptr = flt_otel_group_release;
+
+	*cur_arg += 2;
+
+	OTELC_RETURN_EX(ACT_RET_PRS_OK, enum act_parse_ret, "%d");
+}
+
+
+/* TCP request content action keywords for the OTel group action. */
+static struct action_kw_list tcp_req_action_kws = { ILH, {
+		{ FLT_OTEL_ACTION_GROUP, flt_otel_group_parse },
+		{ /* END */ },
+	}
+};
+
+INITCALL1(STG_REGISTER, tcp_req_cont_keywords_register, &tcp_req_action_kws);
+
+/* TCP response content action keywords for the OTel group action. */
+static struct action_kw_list tcp_res_action_kws = { ILH, {
+		{ FLT_OTEL_ACTION_GROUP, flt_otel_group_parse },
+		{ /* END */ },
+	}
+};
+
+INITCALL1(STG_REGISTER, tcp_res_cont_keywords_register, &tcp_res_action_kws);
+
+/* HTTP request action keywords for the OTel group action. */
+static struct action_kw_list http_req_action_kws = { ILH, {
+		{ FLT_OTEL_ACTION_GROUP, flt_otel_group_parse },
+		{ /* END */ },
+	}
+};
+
+INITCALL1(STG_REGISTER, http_req_keywords_register, &http_req_action_kws);
+
+/* HTTP response action keywords for the OTel group action. */
+static struct action_kw_list http_res_action_kws = { ILH, {
+		{ FLT_OTEL_ACTION_GROUP, flt_otel_group_parse },
+		{ /* END */ },
+	}
+};
+
+INITCALL1(STG_REGISTER, http_res_keywords_register, &http_res_action_kws);
+
+/* HTTP after-response action keywords for the OTel group action. */
+static struct action_kw_list http_after_res_actions_kws = { ILH, {
+		{ FLT_OTEL_ACTION_GROUP, flt_otel_group_parse },
+		{ /* END */ },
+	}
+};
+
+INITCALL1(STG_REGISTER, http_after_res_keywords_register, &http_after_res_actions_kws);
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/http.c

@@ -0,0 +1,324 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+#ifdef DEBUG_OTEL
+
+/***
+ * NAME
+ *   flt_otel_http_headers_dump - debug HTTP headers dump
+ *
+ * SYNOPSIS
+ *   void flt_otel_http_headers_dump(const struct channel *chn)
+ *
+ * ARGUMENTS
+ *   chn - channel to dump HTTP headers from
+ *
+ * DESCRIPTION
+ *   Dumps all HTTP headers from the channel's HTX buffer.  Iterates over HTX
+ *   blocks, logging each header name-value pair at NOTICE level.  Processing
+ *   stops at the end-of-headers marker.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_http_headers_dump(const struct channel *chn)
+{
+	const struct htx *htx;
+	int32_t           pos;
+
+	OTELC_FUNC("%p", chn);
+
+	if (chn == NULL)
+		OTELC_RETURN();
+
+	htx = htxbuf(&(chn->buf));
+
+	if (htx_is_empty(htx))
+		OTELC_RETURN();
+
+	/* Walk HTX blocks and log each header until end-of-headers. */
+	for (pos = htx_get_first(htx); pos != -1; pos = htx_get_next(htx, pos)) {
+		struct htx_blk    *blk  = htx_get_blk(htx, pos);
+		enum htx_blk_type  type = htx_get_blk_type(blk);
+
+		if (type == HTX_BLK_HDR) {
+			struct ist n = htx_get_blk_name(htx, blk);
+			struct ist v = htx_get_blk_value(htx, blk);
+
+			OTELC_DBG(NOTICE, "'%.*s: %.*s'", (int)n.len, n.ptr, (int)v.len, v.ptr);
+		}
+		else if (type == HTX_BLK_EOH)
+			break;
+	}
+
+	OTELC_RETURN();
+}
+
+#endif /* DEBUG_OTEL */
+
+
+/***
+ * NAME
+ *   flt_otel_http_headers_get - HTTP header extraction to text map
+ *
+ * SYNOPSIS
+ *   struct otelc_text_map *flt_otel_http_headers_get(struct channel *chn, const char *prefix, size_t len, char **err)
+ *
+ * ARGUMENTS
+ *   chn    - channel containing HTTP headers
+ *   prefix - header name prefix to match (or NULL for all)
+ *   len    - length of the prefix string
+ *   err    - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Extracts HTTP headers matching a <prefix> from the channel's HTX buffer
+ *   into a newly allocated text map.  When <prefix> is NULL or its length is
+ *   zero, all headers are extracted.  If the prefix starts with
+ *   FLT_OTEL_PARSE_CTX_IGNORE_NAME, prefix matching is bypassed.  The prefix
+ *   (including the separator dash) is stripped from header names before storing
+ *   in the text map.  Empty header values are replaced with an empty string to
+ *   avoid misinterpretation by otelc_text_map_add().  This function is used by
+ *   the "extract" keyword to read span context from incoming request headers.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the populated text map, or NULL on failure or when
+ *   no matching headers are found.
+ */
+struct otelc_text_map *flt_otel_http_headers_get(struct channel *chn, const char *prefix, size_t len, char **err)
+{
+	const struct htx    *htx;
+	size_t               prefix_len = (!OTELC_STR_IS_VALID(prefix) || (len == 0)) ? 0 : (len + 1);
+	int32_t              pos;
+	struct otelc_text_map *retptr = NULL;
+
+	OTELC_FUNC("%p, \"%s\", %zu, %p:%p", chn, OTELC_STR_ARG(prefix), len, OTELC_DPTR_ARGS(err));
+
+	if (chn == NULL)
+		OTELC_RETURN_PTR(retptr);
+
+	/*
+	 * The keyword 'inject' allows you to define the name of the OpenTelemetry
+	 * context without using a prefix.  In that case all HTTP headers are
+	 * transferred because it is not possible to separate them from the
+	 * OpenTelemetry context (this separation is usually done via a prefix).
+	 *
+	 * When using the 'extract' keyword, the context name must be specified.
+	 * To allow all HTTP headers to be extracted, the first character of
+	 * that name must be set to FLT_OTEL_PARSE_CTX_IGNORE_NAME.
+	 */
+	if (OTELC_STR_IS_VALID(prefix) && (*prefix == FLT_OTEL_PARSE_CTX_IGNORE_NAME))
+		prefix_len = 0;
+
+	htx = htxbuf(&(chn->buf));
+
+	for (pos = htx_get_first(htx); pos != -1; pos = htx_get_next(htx, pos)) {
+		struct htx_blk    *blk  = htx_get_blk(htx, pos);
+		enum htx_blk_type  type = htx_get_blk_type(blk);
+
+		if (type == HTX_BLK_HDR) {
+			struct ist v, n = htx_get_blk_name(htx, blk);
+
+			if ((prefix_len == 0) || ((n.len >= prefix_len) && (strncasecmp(n.ptr, prefix, len) == 0))) {
+				if (retptr == NULL) {
+					retptr = OTELC_TEXT_MAP_NEW(NULL, 8);
+					if (retptr == NULL) {
+						FLT_OTEL_ERR("failed to create HTTP header data");
+
+						break;
+					}
+				}
+
+				v = htx_get_blk_value(htx, blk);
+
+				/*
+				 * In case the data of the HTTP header is not
+				 * specified, v.ptr will have some non-null
+				 * value and v.len will be equal to 0.  The
+				 * otelc_text_map_add() function will not
+				 * interpret this well.  In this case v.ptr
+				 * is set to an empty string.
+				 */
+				if (v.len == 0)
+					v = ist("");
+
+				/*
+				 * Here, an HTTP header (which is actually part
+				 * of the span context is added to the text_map.
+				 *
+				 * Before adding, the prefix is removed from the
+				 * HTTP header name.
+				 */
+				if (OTELC_TEXT_MAP_ADD(retptr, n.ptr + prefix_len, n.len - prefix_len, v.ptr, v.len, OTELC_TEXT_MAP_AUTO) == -1) {
+					FLT_OTEL_ERR("failed to add HTTP header data");
+
+					otelc_text_map_destroy(&retptr);
+
+					break;
+				}
+			}
+		}
+		else if (type == HTX_BLK_EOH)
+			break;
+	}
+
+	OTELC_TEXT_MAP_DUMP(retptr, "extracted HTTP headers");
+
+	if ((retptr != NULL) && (retptr->count == 0)) {
+		OTELC_DBG(NOTICE, "WARNING: no HTTP headers found");
+
+		otelc_text_map_destroy(&retptr);
+	}
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_http_header_set - HTTP header set or remove
+ *
+ * SYNOPSIS
+ *   int flt_otel_http_header_set(struct channel *chn, const char *prefix, const char *name, const char *value, char **err)
+ *
+ * ARGUMENTS
+ *   chn    - channel containing HTTP headers
+ *   prefix - header name prefix (or NULL)
+ *   name   - header name suffix (or NULL)
+ *   value  - header value to set (or NULL to remove only)
+ *   err    - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Sets or removes an HTTP header in the channel's HTX buffer.  The full
+ *   header name is constructed by combining <prefix> and <name> with a dash
+ *   separator; if only one is provided, it is used directly.  All existing
+ *   occurrences of the header are removed first.  If <name> is NULL, all
+ *   headers starting with <prefix> are removed.  If <value> is non-NULL, the
+ *   header is then added with the new value.  A NULL <value> causes only the
+ *   removal, with no subsequent addition.
+ *
+ * RETURN VALUE
+ *   Returns 0 on success, or FLT_OTEL_RET_ERROR on failure.
+ */
+int flt_otel_http_header_set(struct channel *chn, const char *prefix, const char *name, const char *value, char **err)
+{
+	struct http_hdr_ctx  ctx = { .blk = NULL };
+	struct ist           ist_name;
+	struct buffer       *buffer = NULL;
+	struct htx          *htx;
+	int                  retval = FLT_OTEL_RET_ERROR;
+
+	OTELC_FUNC("%p, \"%s\", \"%s\", \"%s\", %p:%p", chn, OTELC_STR_ARG(prefix), OTELC_STR_ARG(name), OTELC_STR_ARG(value), OTELC_DPTR_ARGS(err));
+
+	if ((chn == NULL) || (!OTELC_STR_IS_VALID(prefix) && !OTELC_STR_IS_VALID(name)))
+		OTELC_RETURN_INT(retval);
+
+	htx = htxbuf(&(chn->buf));
+
+	/*
+	 * Very rare (about 1% of cases), htx is empty.
+	 * In order to avoid segmentation fault, we exit this function.
+	 */
+	if (htx_is_empty(htx)) {
+		FLT_OTEL_ERR("HTX is empty");
+
+		OTELC_RETURN_INT(retval);
+	}
+
+	if (!OTELC_STR_IS_VALID(prefix)) {
+		ist_name = ist2((char *)name, strlen(name));
+	}
+	else if (!OTELC_STR_IS_VALID(name)) {
+		ist_name = ist2((char *)prefix, strlen(prefix));
+	}
+	else {
+		buffer = flt_otel_trash_alloc(0, err);
+		if (buffer == NULL)
+			OTELC_RETURN_INT(retval);
+
+		(void)chunk_printf(buffer, "%s-%s", prefix, name);
+
+		ist_name = ist2(buffer->area, buffer->data);
+	}
+
+	/* Remove all occurrences of the header. */
+	while (http_find_header(htx, ist(""), &ctx, 1) == 1) {
+		struct ist n = htx_get_blk_name(htx, ctx.blk);
+#ifdef DEBUG_OTEL
+		struct ist v = htx_get_blk_value(htx, ctx.blk);
+#endif
+
+		/*
+		 * If the <name> parameter is not set, then remove all headers
+		 * that start with the contents of the <prefix> parameter.
+		 */
+		if (!OTELC_STR_IS_VALID(name))
+			n.len = ist_name.len;
+
+		if (isteqi(n, ist_name))
+			if (http_remove_header(htx, &ctx) == 1)
+				OTELC_DBG(DEBUG, "HTTP header '%.*s: %.*s' removed", (int)n.len, n.ptr, (int)v.len, v.ptr);
+	}
+
+	/*
+	 * If the value pointer has a value of NULL, the HTTP header is not set
+	 * after deletion.
+	 */
+	if (value == NULL) {
+		retval = 0;
+	}
+	else if (http_add_header(htx, ist_name, ist(value)) == 1) {
+		retval = 0;
+
+		OTELC_DBG(DEBUG, "HTTP header '%s: %s' added", ist_name.ptr, value);
+	}
+	else {
+		FLT_OTEL_ERR("failed to set HTTP header '%s: %s'", ist_name.ptr, value);
+	}
+
+	flt_otel_trash_free(&buffer);
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_http_headers_remove - HTTP headers removal by prefix
+ *
+ * SYNOPSIS
+ *   int flt_otel_http_headers_remove(struct channel *chn, const char *prefix, char **err)
+ *
+ * ARGUMENTS
+ *   chn    - channel containing HTTP headers
+ *   prefix - header name prefix to match for removal
+ *   err    - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Removes all HTTP headers matching the given <prefix> from the channel's HTX
+ *   buffer.  This is a convenience wrapper around flt_otel_http_header_set()
+ *   with NULL <name> and <value> arguments.
+ *
+ * RETURN VALUE
+ *   Returns 0 on success, or FLT_OTEL_RET_ERROR on failure.
+ */
+int flt_otel_http_headers_remove(struct channel *chn, const char *prefix, char **err)
+{
+	int retval;
+
+	OTELC_FUNC("%p, \"%s\", %p:%p", chn, OTELC_STR_ARG(prefix), OTELC_DPTR_ARGS(err));
+
+	retval = flt_otel_http_header_set(chn, prefix, NULL, NULL, err);
+
+	OTELC_RETURN_INT(retval);
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/otelc.c

@@ -0,0 +1,289 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+/***
+ * NAME
+ *   flt_otel_text_map_writer_set_cb - text map injection writer callback
+ *
+ * SYNOPSIS
+ *   static int flt_otel_text_map_writer_set_cb(struct otelc_text_map_writer *writer, const char *key, const char *value)
+ *
+ * ARGUMENTS
+ *   writer - text map writer instance
+ *   key    - context key name
+ *   value  - context key value
+ *
+ * DESCRIPTION
+ *   Writer callback for text map injection.  Called by the OTel C wrapper
+ *   library during span context injection to store each key-value pair in the
+ *   <writer>'s text map.
+ *
+ * RETURN VALUE
+ *   Returns the result of OTELC_TEXT_MAP_ADD().
+ */
+static int flt_otel_text_map_writer_set_cb(struct otelc_text_map_writer *writer, const char *key, const char *value)
+{
+	OTELC_FUNC("%p, \"%s\", \"%s\"", writer, OTELC_STR_ARG(key), OTELC_STR_ARG(value));
+
+	OTELC_RETURN_INT(OTELC_TEXT_MAP_ADD(&(writer->text_map), key, 0, value, 0, OTELC_TEXT_MAP_AUTO));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_http_headers_writer_set_cb - HTTP headers injection writer callback
+ *
+ * SYNOPSIS
+ *   static int flt_otel_http_headers_writer_set_cb(struct otelc_http_headers_writer *writer, const char *key, const char *value)
+ *
+ * ARGUMENTS
+ *   writer - HTTP headers writer instance
+ *   key    - context key name
+ *   value  - context key value
+ *
+ * DESCRIPTION
+ *   Writer callback for HTTP headers injection.  Called by the OTel C wrapper
+ *   library during span context injection to store each key-value pair in the
+ *   <writer>'s text map.
+ *
+ * RETURN VALUE
+ *   Returns the result of OTELC_TEXT_MAP_ADD().
+ */
+static int flt_otel_http_headers_writer_set_cb(struct otelc_http_headers_writer *writer, const char *key, const char *value)
+{
+	OTELC_FUNC("%p, \"%s\", \"%s\"", writer, OTELC_STR_ARG(key), OTELC_STR_ARG(value));
+
+	OTELC_RETURN_INT(OTELC_TEXT_MAP_ADD(&(writer->text_map), key, 0, value, 0, OTELC_TEXT_MAP_AUTO));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_inject_text_map - text map context injection
+ *
+ * SYNOPSIS
+ *   int flt_otel_inject_text_map(const struct otelc_span *span, struct otelc_text_map_writer *carrier)
+ *
+ * ARGUMENTS
+ *   span    - span instance to inject context from
+ *   carrier - text map writer carrier
+ *
+ * DESCRIPTION
+ *   Injects the span context into a text map carrier.  Initializes the
+ *   <carrier> structure, sets the writer callback to
+ *   flt_otel_text_map_writer_set_cb(), and delegates to the <span>'s
+ *   inject_text_map() method.
+ *
+ * RETURN VALUE
+ *   Returns the result of the <span>'s inject_text_map() method,
+ *   or FLT_OTEL_RET_ERROR if arguments are NULL.
+ */
+int flt_otel_inject_text_map(const struct otelc_span *span, struct otelc_text_map_writer *carrier)
+{
+	OTELC_FUNC("%p, %p", span, carrier);
+
+	if ((span == NULL) || (carrier == NULL))
+		OTELC_RETURN_INT(FLT_OTEL_RET_ERROR);
+
+	(void)memset(carrier, 0, sizeof(*carrier));
+	carrier->set = flt_otel_text_map_writer_set_cb;
+
+	OTELC_RETURN_INT(OTELC_OPS(span, inject_text_map, carrier));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_inject_http_headers - HTTP headers context injection
+ *
+ * SYNOPSIS
+ *   int flt_otel_inject_http_headers(const struct otelc_span *span, struct otelc_http_headers_writer *carrier)
+ *
+ * ARGUMENTS
+ *   span    - span instance to inject context from
+ *   carrier - HTTP headers writer carrier
+ *
+ * DESCRIPTION
+ *   Injects the span context into an HTTP headers carrier.  Initializes the
+ *   <carrier> structure, sets the writer callback to
+ *   flt_otel_http_headers_writer_set_cb(), and delegates to the <span>'s
+ *   inject_http_headers() method.
+ *
+ * RETURN VALUE
+ *   Returns the result of the <span>'s inject_http_headers() method,
+ *   or FLT_OTEL_RET_ERROR if arguments are NULL.
+ */
+int flt_otel_inject_http_headers(const struct otelc_span *span, struct otelc_http_headers_writer *carrier)
+{
+	OTELC_FUNC("%p, %p", span, carrier);
+
+	if ((span == NULL) || (carrier == NULL))
+		OTELC_RETURN_INT(FLT_OTEL_RET_ERROR);
+
+	(void)memset(carrier, 0, sizeof(*carrier));
+	carrier->set = flt_otel_http_headers_writer_set_cb;
+
+	OTELC_RETURN_INT(OTELC_OPS(span, inject_http_headers, carrier));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_text_map_reader_foreach_key_cb - text map extraction reader callback
+ *
+ * SYNOPSIS
+ *   static int flt_otel_text_map_reader_foreach_key_cb(const struct otelc_text_map_reader *reader, int (*handler)(void *arg, const char *key, const char *value), void *arg)
+ *
+ * ARGUMENTS
+ *   reader  - text map reader instance
+ *   handler - callback function invoked for each key-value pair
+ *   arg     - opaque argument passed to the handler
+ *
+ * DESCRIPTION
+ *   Reader callback for text map extraction.  Iterates over all key-value
+ *   pairs in the <reader>'s text map and invokes <handler> for each.  Iteration
+ *   stops if the <handler> returns -1.
+ *
+ * RETURN VALUE
+ *   Returns the last <handler> return value, or 0 if the text map is empty.
+ */
+static int flt_otel_text_map_reader_foreach_key_cb(const struct otelc_text_map_reader *reader, int (*handler)(void *arg, const char *key, const char *value), void *arg)
+{
+	size_t i;
+	int    retval = 0;
+
+	OTELC_FUNC("%p, %p, %p", reader, handler, arg);
+
+	for (i = 0; (retval != -1) && (i < reader->text_map.count); i++) {
+		OTELC_DBG(OTELC, "\"%s\" -> \"%s\"", OTELC_STR_ARG(reader->text_map.key[i]), OTELC_STR_ARG(reader->text_map.value[i]));
+
+		retval = handler(arg, reader->text_map.key[i], reader->text_map.value[i]);
+	}
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_http_headers_reader_foreach_key_cb - HTTP headers extraction reader callback
+ *
+ * SYNOPSIS
+ *   static int flt_otel_http_headers_reader_foreach_key_cb(const struct otelc_http_headers_reader *reader, int (*handler)(void *arg, const char *key, const char *value), void *arg)
+ *
+ * ARGUMENTS
+ *   reader  - HTTP headers reader instance
+ *   handler - callback function invoked for each key-value pair
+ *   arg     - opaque argument passed to the handler
+ *
+ * DESCRIPTION
+ *   Reader callback for HTTP headers extraction.  Iterates over all key-value
+ *   pairs in the <reader>'s text map and invokes <handler> for each.  Iteration
+ *   stops if the <handler> returns -1.
+ *
+ * RETURN VALUE
+ *   Returns the last <handler> return value, or 0 if the text map is empty.
+ */
+static int flt_otel_http_headers_reader_foreach_key_cb(const struct otelc_http_headers_reader *reader, int (*handler)(void *arg, const char *key, const char *value), void *arg)
+{
+	size_t i;
+	int    retval = 0;
+
+	OTELC_FUNC("%p, %p, %p", reader, handler, arg);
+
+	for (i = 0; (retval != -1) && (i < reader->text_map.count); i++) {
+		OTELC_DBG(OTELC, "\"%s\" -> \"%s\"", OTELC_STR_ARG(reader->text_map.key[i]), OTELC_STR_ARG(reader->text_map.value[i]));
+
+		retval = handler(arg, reader->text_map.key[i], reader->text_map.value[i]);
+	}
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_extract_text_map - text map context extraction
+ *
+ * SYNOPSIS
+ *   struct otelc_span_context *flt_otel_extract_text_map(struct otelc_tracer *tracer, struct otelc_text_map_reader *carrier, const struct otelc_text_map *text_map)
+ *
+ * ARGUMENTS
+ *   tracer   - OTel tracer instance
+ *   carrier  - text map reader carrier
+ *   text_map - text map containing the context data (or NULL)
+ *
+ * DESCRIPTION
+ *   Extracts a span context from a text map carrier via the <tracer>.
+ *   Initializes the <carrier> structure, sets the foreach_key callback to
+ *   flt_otel_text_map_reader_foreach_key_cb(), and copies the <text_map> data
+ *   into the <carrier>.  Delegates to the <tracer>'s extract_text_map() method.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the extracted span context, or NULL on failure.
+ */
+struct otelc_span_context *flt_otel_extract_text_map(struct otelc_tracer *tracer, struct otelc_text_map_reader *carrier, const struct otelc_text_map *text_map)
+{
+	OTELC_FUNC("%p, %p, %p", tracer, carrier, text_map);
+
+	if ((tracer == NULL) || (carrier == NULL))
+		OTELC_RETURN_PTR(NULL);
+
+	(void)memset(carrier, 0, sizeof(*carrier));
+	carrier->foreach_key = flt_otel_text_map_reader_foreach_key_cb;
+
+	if (text_map != NULL)
+		(void)memcpy(&(carrier->text_map), text_map, sizeof(carrier->text_map));
+
+	OTELC_RETURN_PTR(OTELC_OPS(tracer, extract_text_map, carrier));
+}
+
+
+/***
+ * NAME
+ *   flt_otel_extract_http_headers - HTTP headers context extraction
+ *
+ * SYNOPSIS
+ *   struct otelc_span_context *flt_otel_extract_http_headers(struct otelc_tracer *tracer, struct otelc_http_headers_reader *carrier, const struct otelc_text_map *text_map)
+ *
+ * ARGUMENTS
+ *   tracer   - OTel tracer instance
+ *   carrier  - HTTP headers reader carrier
+ *   text_map - text map containing the context data (or NULL)
+ *
+ * DESCRIPTION
+ *   Extracts a span context from an HTTP headers carrier via the <tracer>.
+ *   Initializes the <carrier> structure, sets the foreach_key callback to
+ *   flt_otel_http_headers_reader_foreach_key_cb(), and copies the <text_map>
+ *   data into the <carrier>.  Delegates to the <tracer>'s
+ *   extract_http_headers() method.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the extracted span context, or NULL on failure.
+ */
+struct otelc_span_context *flt_otel_extract_http_headers(struct otelc_tracer *tracer, struct otelc_http_headers_reader *carrier, const struct otelc_text_map *text_map)
+{
+	OTELC_FUNC("%p, %p, %p", tracer, carrier, text_map);
+
+	if ((tracer == NULL) || (carrier == NULL))
+		OTELC_RETURN_PTR(NULL);
+
+	(void)memset(carrier, 0, sizeof(*carrier));
+	carrier->foreach_key = flt_otel_http_headers_reader_foreach_key_cb;
+
+	if (text_map != NULL)
+		(void)memcpy(&(carrier->text_map), text_map, sizeof(carrier->text_map));
+
+	OTELC_RETURN_PTR(OTELC_OPS(tracer, extract_http_headers, carrier));
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/pool.c

@@ -0,0 +1,385 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+struct pool_head *pool_head_otel_scope_span __read_mostly = NULL;
+struct pool_head *pool_head_otel_scope_context __read_mostly = NULL;
+struct pool_head *pool_head_otel_runtime_context __read_mostly = NULL;
+struct pool_head *pool_head_otel_span_context __read_mostly = NULL;
+
+#ifdef USE_POOL_OTEL_SCOPE_SPAN
+REGISTER_POOL(&pool_head_otel_scope_span, "otel_scope_span", sizeof(struct flt_otel_scope_span));
+#endif
+#ifdef USE_POOL_OTEL_SCOPE_CONTEXT
+REGISTER_POOL(&pool_head_otel_scope_context, "otel_scope_context", sizeof(struct flt_otel_scope_context));
+#endif
+#ifdef USE_POOL_OTEL_RUNTIME_CONTEXT
+REGISTER_POOL(&pool_head_otel_runtime_context, "otel_runtime_context", sizeof(struct flt_otel_runtime_context));
+#endif
+#ifdef USE_POOL_OTEL_SPAN_CONTEXT
+REGISTER_POOL(&pool_head_otel_span_context, "otel_span_context", MAX(sizeof(struct otelc_span), sizeof(struct otelc_span_context)));
+#endif
+
+
+/***
+ * NAME
+ *   flt_otel_pool_alloc - pool-aware memory allocation
+ *
+ * SYNOPSIS
+ *   void *flt_otel_pool_alloc(struct pool_head *pool, size_t size, bool flag_clear, char **err)
+ *
+ * ARGUMENTS
+ *   pool       - HAProxy memory pool to allocate from (or NULL for heap)
+ *   size       - number of bytes to allocate
+ *   flag_clear - whether to zero-fill the allocated memory
+ *   err        - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates <size> bytes of memory from the HAProxy memory <pool>.  If <pool>
+ *   is NULL, the allocation falls back to the heap via OTELC_MALLOC().  When
+ *   <flag_clear> is set, the allocated memory is zero-filled.  On allocation
+ *   failure, an error message is stored via <err>.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the allocated memory, or NULL on failure.
+ */
+void *flt_otel_pool_alloc(struct pool_head *pool, size_t size, bool flag_clear, char **err)
+{
+	void *retptr;
+
+	OTELC_FUNC("%p, %zu, %hhu, %p:%p", pool, size, flag_clear, OTELC_DPTR_ARGS(err));
+
+	if (pool != NULL) {
+		retptr = pool_alloc(pool);
+		if (retptr != NULL)
+			OTELC_DBG(NOTICE, "POOL_ALLOC: %s:%d(%p %zu)", __func__, __LINE__, retptr, FLT_OTEL_DEREF(pool, size, size));
+	} else {
+		retptr = OTELC_MALLOC(size);
+	}
+
+	if (retptr == NULL)
+		FLT_OTEL_ERR("out of memory");
+	else if (flag_clear)
+		(void)memset(retptr, 0, size);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_pool_strndup - pool-aware string duplication
+ *
+ * SYNOPSIS
+ *   void *flt_otel_pool_strndup(struct pool_head *pool, const char *s, size_t size, char **err)
+ *
+ * ARGUMENTS
+ *   pool - HAProxy memory pool to allocate from (or NULL for heap)
+ *   s    - source string to duplicate
+ *   size - maximum number of characters to copy
+ *   err  - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Duplicates up to <size> characters from the string <s> using the HAProxy
+ *   memory <pool>.  If <pool> is NULL, the duplication falls back to
+ *   OTELC_STRNDUP().  When using a pool, the copy is truncated to <pool>->size-1
+ *   bytes and null-terminated.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the duplicated string, or NULL on failure.
+ */
+void *flt_otel_pool_strndup(struct pool_head *pool, const char *s, size_t size, char **err)
+{
+	void *retptr;
+
+	OTELC_FUNC("%p, \"%.*s\", %zu, %p:%p", pool, (int)size, s, size, OTELC_DPTR_ARGS(err));
+
+	if (pool != NULL) {
+		retptr = pool_alloc(pool);
+		if (retptr != NULL) {
+			(void)memcpy(retptr, s, MIN(pool->size - 1, size));
+
+			((uint8_t *)retptr)[MIN(pool->size - 1, size)] = '\0';
+		}
+	} else {
+		retptr = OTELC_STRNDUP(s, size);
+	}
+
+	if (retptr != NULL)
+		OTELC_DBG(NOTICE, "POOL_STRNDUP: %s:%d(%p %zu)", __func__, __LINE__, retptr, FLT_OTEL_DEREF(pool, size, size));
+	else
+		FLT_OTEL_ERR("out of memory");
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_pool_free - pool-aware memory deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_pool_free(struct pool_head *pool, void **ptr)
+ *
+ * ARGUMENTS
+ *   pool - HAProxy memory pool to return memory to (or NULL for heap)
+ *   ptr  - indirect pointer to the memory to free
+ *
+ * DESCRIPTION
+ *   Returns memory referenced by <*ptr> to the HAProxy memory <pool>.  If
+ *   <pool> is NULL, the memory is freed via OTELC_SFREE().  The pointer <*ptr>
+ *   is set to NULL after freeing.  If <ptr> is NULL or <*ptr> is already NULL,
+ *   the function returns immediately.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_pool_free(struct pool_head *pool, void **ptr)
+{
+	OTELC_FUNC("%p, %p:%p", pool, OTELC_DPTR_ARGS(ptr));
+
+	if ((ptr == NULL) || (*ptr == NULL))
+		OTELC_RETURN();
+
+	OTELC_DBG(NOTICE, "POOL_FREE: %s:%d(%p %u)", __func__, __LINE__, *ptr, FLT_OTEL_DEREF(pool, size, 0));
+
+	if (pool != NULL)
+		pool_free(pool, *ptr);
+	else
+		OTELC_SFREE(*ptr);
+
+	*ptr = NULL;
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_pool_init - OTel filter memory pool initialization
+ *
+ * SYNOPSIS
+ *   int flt_otel_pool_init(void)
+ *
+ * ARGUMENTS
+ *   This function takes no arguments.
+ *
+ * DESCRIPTION
+ *   Initializes all memory pools used by the OTel filter.  Each pool is
+ *   created only when the corresponding USE_POOL_OTEL_* macro is defined.
+ *
+ * RETURN VALUE
+ *   Returns FLT_OTEL_RET_OK on success, FLT_OTEL_RET_ERROR on failure.
+ */
+int flt_otel_pool_init(void)
+{
+	int retval = FLT_OTEL_RET_OK;
+
+	OTELC_FUNC("");
+
+#ifdef USE_POOL_OTEL_SCOPE_SPAN
+	FLT_OTEL_POOL_INIT(pool_head_otel_scope_span, "otel_scope_span", sizeof(struct flt_otel_scope_span), retval);
+#endif
+#ifdef USE_POOL_OTEL_SCOPE_CONTEXT
+	FLT_OTEL_POOL_INIT(pool_head_otel_scope_context, "otel_scope_context", sizeof(struct flt_otel_scope_context), retval);
+#endif
+#ifdef USE_POOL_OTEL_RUNTIME_CONTEXT
+	FLT_OTEL_POOL_INIT(pool_head_otel_runtime_context, "otel_runtime_context", sizeof(struct flt_otel_runtime_context), retval);
+#endif
+#ifdef USE_POOL_OTEL_SPAN_CONTEXT
+	FLT_OTEL_POOL_INIT(pool_head_otel_span_context, "otel_span_context", OTELC_MAX(sizeof(struct otelc_span), sizeof(struct otelc_span_context)), retval);
+#endif
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_pool_destroy - OTel filter memory pool destruction
+ *
+ * SYNOPSIS
+ *   void flt_otel_pool_destroy(void)
+ *
+ * ARGUMENTS
+ *   This function takes no arguments.
+ *
+ * DESCRIPTION
+ *   Destroys all memory pools used by the OTel filter.  Each pool is
+ *   destroyed only when the corresponding USE_POOL_OTEL_* macro is defined.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_pool_destroy(void)
+{
+	OTELC_FUNC("");
+
+#ifdef USE_POOL_OTEL_SCOPE_SPAN
+	FLT_OTEL_POOL_DESTROY(pool_head_otel_scope_span);
+#endif
+#ifdef USE_POOL_OTEL_SCOPE_CONTEXT
+	FLT_OTEL_POOL_DESTROY(pool_head_otel_scope_context);
+#endif
+#ifdef USE_POOL_OTEL_RUNTIME_CONTEXT
+	FLT_OTEL_POOL_DESTROY(pool_head_otel_runtime_context);
+#endif
+#ifdef USE_POOL_OTEL_SPAN_CONTEXT
+	FLT_OTEL_POOL_DESTROY(pool_head_otel_span_context);
+#endif
+
+	OTELC_RETURN();
+}
+
+
+#ifdef DEBUG_OTEL
+
+/***
+ * NAME
+ *   flt_otel_pool_info - debug pool sizes logging
+ *
+ * SYNOPSIS
+ *   void flt_otel_pool_info(void)
+ *
+ * ARGUMENTS
+ *   This function takes no arguments.
+ *
+ * DESCRIPTION
+ *   Logs the sizes of all registered HAProxy memory pools used by the OTel
+ *   filter (buffer, trash, scope_span, scope_context, runtime_context).
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_pool_info(void)
+{
+	OTELC_DBG(NOTICE, "--- pool info ----------");
+
+	/*
+	 * In case we have some error in the configuration file,
+	 * it is possible that this pool was not initialized.
+	 */
+#ifdef USE_POOL_BUFFER
+	OTELC_DBG(NOTICE, "  buffer: %p %u", pool_head_buffer, FLT_OTEL_DEREF(pool_head_buffer, size, 0));
+#endif
+#ifdef USE_TRASH_CHUNK
+	OTELC_DBG(NOTICE, "  trash: %p %u", pool_head_trash, FLT_OTEL_DEREF(pool_head_trash, size, 0));
+#endif
+
+#ifdef USE_POOL_OTEL_SCOPE_SPAN
+	OTELC_DBG(NOTICE, "  otel_scope_span: %p %u", pool_head_otel_scope_span, FLT_OTEL_DEREF(pool_head_otel_scope_span, size, 0));
+#endif
+#ifdef USE_POOL_OTEL_SCOPE_CONTEXT
+	OTELC_DBG(NOTICE, "  otel_scope_context: %p %u", pool_head_otel_scope_context, FLT_OTEL_DEREF(pool_head_otel_scope_context, size, 0));
+#endif
+#ifdef USE_POOL_OTEL_RUNTIME_CONTEXT
+	OTELC_DBG(NOTICE, "  otel_runtime_context: %p %u", pool_head_otel_runtime_context, FLT_OTEL_DEREF(pool_head_otel_runtime_context, size, 0));
+#endif
+#ifdef USE_POOL_OTEL_SPAN_CONTEXT
+	OTELC_DBG(NOTICE, "  otel_span_context: %p %u", pool_head_otel_span_context, FLT_OTEL_DEREF(pool_head_otel_span_context, size, 0));
+#endif
+}
+
+#endif /* DEBUG_OTEL */
+
+
+/***
+ * NAME
+ *   flt_otel_trash_alloc - trash buffer allocation
+ *
+ * SYNOPSIS
+ *   struct buffer *flt_otel_trash_alloc(bool flag_clear, char **err)
+ *
+ * ARGUMENTS
+ *   flag_clear - whether to zero-fill the buffer area
+ *   err        - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates a temporary buffer chunk for use as scratch space.  When
+ *   USE_TRASH_CHUNK is defined, the buffer is obtained via alloc_trash_chunk();
+ *   otherwise, a buffer structure and its data area are allocated from the heap
+ *   using global.tune.bufsize as the buffer size.  When <flag_clear> is set,
+ *   the buffer's data area is zero-filled.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the allocated buffer, or NULL on failure.
+ */
+struct buffer *flt_otel_trash_alloc(bool flag_clear, char **err)
+{
+	struct buffer *retptr;
+
+	OTELC_FUNC("%hhu, %p:%p", flag_clear, OTELC_DPTR_ARGS(err));
+
+#ifdef USE_TRASH_CHUNK
+	retptr = alloc_trash_chunk();
+	if (retptr != NULL)
+		OTELC_DBG(NOTICE, "TRASH_ALLOC: %s:%d(%p %zu)", __func__, __LINE__, retptr, retptr->size);
+#else
+	retptr = OTELC_MALLOC(sizeof(*retptr));
+	if (retptr != NULL) {
+		chunk_init(retptr, OTELC_MALLOC(global.tune.bufsize), global.tune.bufsize);
+		if (retptr->area == NULL)
+			OTELC_SFREE_CLEAR(retptr);
+		else
+			*(retptr->area) = '\0';
+	}
+#endif
+
+	if (retptr == NULL)
+		FLT_OTEL_ERR("out of memory");
+	else if (flag_clear)
+		(void)memset(retptr->area, 0, retptr->size);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_trash_free - trash buffer deallocation
+ *
+ * SYNOPSIS
+ *   void flt_otel_trash_free(struct buffer **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - indirect pointer to the buffer to free
+ *
+ * DESCRIPTION
+ *   Frees a trash buffer chunk previously allocated by flt_otel_trash_alloc().
+ *   When USE_TRASH_CHUNK is defined, the buffer is freed via
+ *   free_trash_chunk(); otherwise, both the data area and the buffer structure
+ *   are freed individually.  The pointer <*ptr> is set to NULL after freeing.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_trash_free(struct buffer **ptr)
+{
+	OTELC_FUNC("%p:%p", OTELC_DPTR_ARGS(ptr));
+
+	if ((ptr == NULL) || (*ptr == NULL))
+		OTELC_RETURN();
+
+	OTELC_DBG(NOTICE, "TRASH_FREE: %s:%d(%p %zu)", __func__, __LINE__, *ptr, (*ptr)->size);
+
+#ifdef USE_TRASH_CHUNK
+	free_trash_chunk(*ptr);
+#else
+	OTELC_SFREE((*ptr)->area);
+	OTELC_SFREE(*ptr);
+#endif
+
+	*ptr = NULL;
+
+	OTELC_RETURN();
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/src/scope.c

@@ -0,0 +1,745 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "../include/include.h"
+
+
+/***
+ * NAME
+ *   flt_otel_runtime_context_init - per-stream runtime context allocation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_runtime_context *flt_otel_runtime_context_init(struct stream *s, struct filter *f, char **err)
+ *
+ * ARGUMENTS
+ *   s   - the stream to which the context belongs
+ *   f   - the filter instance
+ *   err - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Allocates and initializes a per-stream runtime context from pool memory.
+ *   It copies the hard-error, disabled and logging flags from the filter
+ *   configuration, generates a UUID and stores it in the sess.otel.uuid
+ *   HAProxy variable.
+ *
+ * RETURN VALUE
+ *   Returns a pointer to the new runtime context, or NULL on failure.
+ */
+struct flt_otel_runtime_context *flt_otel_runtime_context_init(struct stream *s, struct filter *f, char **err)
+{
+	const struct flt_otel_conf      *conf = FLT_OTEL_CONF(f);
+	struct buffer                    uuid;
+	struct flt_otel_runtime_context *retptr = NULL;
+
+	OTELC_FUNC("%p, %p, %p:%p", s, f, OTELC_DPTR_ARGS(err));
+
+	retptr = flt_otel_pool_alloc(pool_head_otel_runtime_context, sizeof(*retptr), 1, err);
+	if (retptr == NULL)
+		OTELC_RETURN_PTR(retptr);
+
+	/* Initialize runtime context fields and generate a session UUID. */
+	retptr->stream        = s;
+	retptr->filter        = f;
+	retptr->flag_harderr  = _HA_ATOMIC_LOAD(&(conf->instr->flag_harderr));
+	retptr->flag_disabled = _HA_ATOMIC_LOAD(&(conf->instr->flag_disabled));
+	retptr->logging       = _HA_ATOMIC_LOAD(&(conf->instr->logging));
+	retptr->idle_timeout  = 0;
+	retptr->idle_exp      = TICK_ETERNITY;
+	LIST_INIT(&(retptr->spans));
+	LIST_INIT(&(retptr->contexts));
+
+	uuid = b_make(retptr->uuid, sizeof(retptr->uuid), 0, 0);
+	ha_generate_uuid_v4(&uuid);
+
+#ifdef USE_OTEL_VARS
+	/*
+	 * The HAProxy variable 'sess.otel.uuid' is registered here,
+	 * after which its value is set to runtime context UUID.
+	 */
+	if (flt_otel_var_register(FLT_OTEL_VAR_UUID, err) != -1)
+		(void)flt_otel_var_set(s, FLT_OTEL_VAR_UUID, retptr->uuid, SMP_OPT_DIR_REQ, err);
+#endif
+
+	FLT_OTEL_DBG_RUNTIME_CONTEXT("session context: ", retptr);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_runtime_context_free - per-stream runtime context cleanup
+ *
+ * SYNOPSIS
+ *   void flt_otel_runtime_context_free(struct filter *f)
+ *
+ * ARGUMENTS
+ *   f - the filter instance whose runtime context is to be freed
+ *
+ * DESCRIPTION
+ *   Frees the per-stream runtime context attached to <f>.  It ends all active
+ *   spans with the current monotonic timestamp, destroys all extracted
+ *   contexts, and returns the pool memory.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_runtime_context_free(struct filter *f)
+{
+	struct flt_otel_runtime_context *rt_ctx = f->ctx;
+
+	OTELC_FUNC("%p", f);
+
+	if (rt_ctx == NULL)
+		OTELC_RETURN();
+
+	FLT_OTEL_DBG_RUNTIME_CONTEXT("session context: ", rt_ctx);
+
+	/* End all active spans with a common timestamp. */
+	if (!LIST_ISEMPTY(&(rt_ctx->spans))) {
+		struct timespec             ts_steady;
+		struct flt_otel_scope_span *span, *span_back;
+
+		/* All spans should be completed at the same time. */
+		(void)clock_gettime(CLOCK_MONOTONIC, &ts_steady);
+
+		list_for_each_entry_safe(span, span_back, &(rt_ctx->spans), list) {
+			OTELC_OPSR(span->span, end_with_options, &ts_steady, OTELC_SPAN_STATUS_IGNORE, NULL);
+			flt_otel_scope_span_free(&span);
+		}
+	}
+
+	/* Destroy all extracted span contexts. */
+	if (!LIST_ISEMPTY(&(rt_ctx->contexts))) {
+		struct flt_otel_scope_context *ctx, *ctx_back;
+
+		list_for_each_entry_safe(ctx, ctx_back, &(rt_ctx->contexts), list)
+			flt_otel_scope_context_free(&ctx);
+	}
+
+	flt_otel_pool_free(pool_head_otel_runtime_context, &(f->ctx));
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_span_init - scope span lookup or creation
+ *
+ * SYNOPSIS
+ *   struct flt_otel_scope_span *flt_otel_scope_span_init(struct flt_otel_runtime_context *rt_ctx, const char *id, size_t id_len, const char *ref_id, size_t ref_id_len, uint dir, char **err)
+ *
+ * ARGUMENTS
+ *   rt_ctx     - the runtime context owning the span list
+ *   id         - the span operation name
+ *   id_len     - length of the <id> string
+ *   ref_id     - the parent span or context name, or NULL
+ *   ref_id_len - length of the <ref_id> string
+ *   dir        - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   err        - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Finds an existing scope span by <id> in the runtime context or creates a
+ *   new one.  If <ref_id> is set, it resolves the parent reference by searching
+ *   the span list first, then the extracted context list.
+ *
+ * RETURN VALUE
+ *   Returns the existing or new scope span, or NULL on failure.
+ */
+struct flt_otel_scope_span *flt_otel_scope_span_init(struct flt_otel_runtime_context *rt_ctx, const char *id, size_t id_len, const char *ref_id, size_t ref_id_len, uint dir, char **err)
+{
+	struct otelc_span             *ref_span = NULL;
+	struct otelc_span_context     *ref_ctx = NULL;
+	struct flt_otel_scope_span    *span, *retptr = NULL;
+	struct flt_otel_scope_context *ctx;
+
+	OTELC_FUNC("%p, \"%s\", %zu, \"%s\", %zu, %u, %p:%p", rt_ctx, OTELC_STR_ARG(id), id_len, OTELC_STR_ARG(ref_id), ref_id_len, dir, OTELC_DPTR_ARGS(err));
+
+	if ((rt_ctx == NULL) || (id == NULL))
+		OTELC_RETURN_PTR(retptr);
+
+	/* Return the existing span if one matches this ID. */
+	list_for_each_entry(span, &(rt_ctx->spans), list)
+		if (FLT_OTEL_CONF_STR_CMP(span->id, id)) {
+			OTELC_DBG(NOTICE, "found span %p", span);
+
+			OTELC_RETURN_PTR(span);
+		}
+
+	/* Resolve the parent reference from spans or contexts. */
+	if (ref_id != NULL) {
+		list_for_each_entry(span, &(rt_ctx->spans), list)
+			if (FLT_OTEL_CONF_STR_CMP(span->id, ref_id)) {
+				ref_span = span->span;
+
+				break;
+			}
+
+		if (ref_span != NULL) {
+			OTELC_DBG(NOTICE, "found referenced span %p", span);
+		} else {
+			list_for_each_entry(ctx, &(rt_ctx->contexts), list)
+				if (FLT_OTEL_CONF_STR_CMP(ctx->id, ref_id)) {
+					ref_ctx = ctx->context;
+
+					break;
+				}
+
+			if (ref_ctx != NULL) {
+				OTELC_DBG(NOTICE, "found referenced context %p", ctx);
+			} else {
+				FLT_OTEL_ERR("cannot find referenced span/context '%s'", ref_id);
+
+				OTELC_RETURN_PTR(retptr);
+			}
+		}
+	}
+
+	retptr = flt_otel_pool_alloc(pool_head_otel_scope_span, sizeof(*retptr), 1, err);
+	if (retptr == NULL)
+		OTELC_RETURN_PTR(retptr);
+
+	/* Populate the new scope span and insert it into the list. */
+	retptr->id          = id;
+	retptr->id_len      = id_len;
+	retptr->smp_opt_dir = dir;
+	retptr->ref_span    = ref_span;
+	retptr->ref_ctx     = ref_ctx;
+	LIST_INSERT(&(rt_ctx->spans), &(retptr->list));
+
+	FLT_OTEL_DBG_SCOPE_SPAN("new span ", retptr);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_span_free - scope span cleanup
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_span_free(struct flt_otel_scope_span **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - pointer to the scope span pointer to free
+ *
+ * DESCRIPTION
+ *   Frees a scope span entry pointed to by <ptr> and removes it from its list.
+ *   If the OTel span is still active (non-NULL), the function refuses to free
+ *   it and returns immediately.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_span_free(struct flt_otel_scope_span **ptr)
+{
+	OTELC_FUNC("%p:%p", OTELC_DPTR_ARGS(ptr));
+
+	if ((ptr == NULL) || (*ptr == NULL))
+		OTELC_RETURN();
+
+	FLT_OTEL_DBG_SCOPE_SPAN("", *ptr);
+
+	/* If the span is still active, do nothing. */
+	if ((*ptr)->span != NULL) {
+		OTELC_DBG(NOTICE, "cannot finish active span");
+
+		OTELC_RETURN();
+	}
+
+	FLT_OTEL_LIST_DEL(&((*ptr)->list));
+	flt_otel_pool_free(pool_head_otel_scope_span, (void **)ptr);
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_context_init - scope context extraction
+ *
+ * SYNOPSIS
+ *   struct flt_otel_scope_context *flt_otel_scope_context_init(struct flt_otel_runtime_context *rt_ctx, struct otelc_tracer *tracer, const char *id, size_t id_len, const struct otelc_text_map *text_map, uint dir, char **err)
+ *
+ * ARGUMENTS
+ *   rt_ctx   - the runtime context owning the context list
+ *   tracer   - the OTel tracer used for context extraction
+ *   id       - the context name
+ *   id_len   - length of the <id> string
+ *   text_map - the carrier text map to extract from
+ *   dir      - the sample fetch direction (SMP_OPT_DIR_REQ/RES)
+ *   err      - indirect pointer to error message string
+ *
+ * DESCRIPTION
+ *   Finds an existing scope context by <id> in the runtime context or creates
+ *   a new one by extracting the span context from the <text_map> carrier via
+ *   the <tracer>.
+ *
+ * RETURN VALUE
+ *   Returns the existing or new scope context, or NULL on failure.
+ */
+struct flt_otel_scope_context *flt_otel_scope_context_init(struct flt_otel_runtime_context *rt_ctx, struct otelc_tracer *tracer, const char *id, size_t id_len, const struct otelc_text_map *text_map, uint dir, char **err)
+{
+	struct otelc_http_headers_reader  reader;
+	struct otelc_span_context        *span_ctx;
+	struct flt_otel_scope_context    *retptr = NULL;
+
+	OTELC_FUNC("%p, %p, \"%s\", %zu, %p, %u, %p:%p", rt_ctx, tracer, OTELC_STR_ARG(id), id_len, text_map, dir, OTELC_DPTR_ARGS(err));
+
+	if ((rt_ctx == NULL) || (tracer == NULL) || (id == NULL) || (text_map == NULL))
+		OTELC_RETURN_PTR(retptr);
+
+	/* Return the existing context if one matches this ID. */
+	list_for_each_entry(retptr, &(rt_ctx->contexts), list)
+		if (FLT_OTEL_CONF_STR_CMP(retptr->id, id)) {
+			OTELC_DBG(NOTICE, "found context %p", retptr);
+
+			OTELC_RETURN_PTR(retptr);
+		}
+
+	retptr = flt_otel_pool_alloc(pool_head_otel_scope_context, sizeof(*retptr), 1, err);
+	if (retptr == NULL)
+		OTELC_RETURN_PTR(retptr);
+
+	span_ctx = flt_otel_extract_http_headers(tracer, &reader, text_map);
+	if (span_ctx == NULL) {
+		flt_otel_scope_context_free(&retptr);
+
+		OTELC_RETURN_PTR(retptr);
+	}
+
+	/* Populate the new scope context and insert it into the list. */
+	retptr->id          = id;
+	retptr->id_len      = id_len;
+	retptr->smp_opt_dir = dir;
+	retptr->context     = span_ctx;
+	LIST_INSERT(&(rt_ctx->contexts), &(retptr->list));
+
+	FLT_OTEL_DBG_SCOPE_CONTEXT("new context ", retptr);
+
+	OTELC_RETURN_PTR(retptr);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_context_free - scope context cleanup
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_context_free(struct flt_otel_scope_context **ptr)
+ *
+ * ARGUMENTS
+ *   ptr - pointer to the scope context pointer to free
+ *
+ * DESCRIPTION
+ *   Frees a scope context entry pointed to by <ptr>.  It destroys the
+ *   underlying OTel span context, removes the entry from its list, and
+ *   returns the pool memory.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_context_free(struct flt_otel_scope_context **ptr)
+{
+	OTELC_FUNC("%p:%p", OTELC_DPTR_ARGS(ptr));
+
+	if ((ptr == NULL) || (*ptr == NULL))
+		OTELC_RETURN();
+
+	FLT_OTEL_DBG_SCOPE_CONTEXT("", *ptr);
+
+	if ((*ptr)->context != NULL)
+		OTELC_OPSR((*ptr)->context, destroy);
+
+	FLT_OTEL_LIST_DEL(&((*ptr)->list));
+	flt_otel_pool_free(pool_head_otel_scope_context, (void **)ptr);
+
+	OTELC_RETURN();
+}
+
+
+#ifdef DEBUG_OTEL
+
+/***
+ * NAME
+ *   flt_otel_scope_data_dump - debug scope data dump
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_data_dump(const struct flt_otel_scope_data *data)
+ *
+ * ARGUMENTS
+ *   data - the scope data structure to dump
+ *
+ * DESCRIPTION
+ *   Dumps the contents of a scope <data> structure for debugging: baggage
+ *   key-value pairs, attributes, events with their attributes, span links,
+ *   and the status code/description.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_data_dump(const struct flt_otel_scope_data *data)
+{
+	size_t i;
+
+	if (data == NULL)
+		return;
+
+	if (data->baggage.attr == NULL) {
+		OTELC_DBG(WORKER, "baggage %p:{ }", &(data->baggage));
+	} else {
+		OTELC_DBG(WORKER, "baggage %p:{", &(data->baggage));
+		for (i = 0; i < data->baggage.cnt; i++)
+			OTELC_DBG_KV(WORKER, "  ", data->baggage.attr + i);
+		OTELC_DBG(WORKER, "}");
+	}
+
+	if (data->attributes.attr == NULL) {
+		OTELC_DBG(WORKER, "attributes %p:{ }", &(data->attributes));
+	} else {
+		OTELC_DBG(WORKER, "attributes %p:{", &(data->attributes));
+		for (i = 0; i < data->attributes.cnt; i++)
+			OTELC_DBG_KV(WORKER, "  ", data->attributes.attr + i);
+		OTELC_DBG(WORKER, "}");
+	}
+
+	if (LIST_ISEMPTY(&(data->events))) {
+		OTELC_DBG(WORKER, "events %p:{ }", &(data->events));
+	} else {
+		struct flt_otel_scope_data_event *event;
+
+		OTELC_DBG(WORKER, "events %p:{", &(data->events));
+		list_for_each_entry_rev(event, &(data->events), list) {
+			OTELC_DBG(WORKER, "  '%s' %zu/%zu", event->name, event->cnt, event->size);
+			if (event->attr != NULL)
+				for (i = 0; i < event->cnt; i++)
+					OTELC_DBG_KV(WORKER, "  ", event->attr + i);
+		}
+		OTELC_DBG(WORKER, "}");
+	}
+
+	if (LIST_ISEMPTY(&(data->links))) {
+		OTELC_DBG(WORKER, "links %p:{ }", &(data->links));
+	} else {
+		struct flt_otel_scope_data_link *link;
+
+		OTELC_DBG(WORKER, "links %p:{", &(data->links));
+		list_for_each_entry(link, &(data->links), list)
+			OTELC_DBG(WORKER, "  %p %p", link->span, link->context);
+		OTELC_DBG(WORKER, "}");
+	}
+
+	if ((data->status.code == 0) && (data->status.description == NULL))
+		OTELC_DBG(WORKER, "status %p:{ }", &(data->status));
+	else
+		FLT_OTEL_DBG_SCOPE_DATA_STATUS("status ", &(data->status));
+}
+
+#endif /* DEBUG_OTEL */
+
+
+/***
+ * NAME
+ *   flt_otel_scope_data_init - scope data zero-initialization
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_data_init(struct flt_otel_scope_data *ptr)
+ *
+ * ARGUMENTS
+ *   ptr - the scope data structure to initialize
+ *
+ * DESCRIPTION
+ *   Zero-initializes the scope data structure pointed to by <ptr> and sets up
+ *   the event and link list heads.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_data_init(struct flt_otel_scope_data *ptr)
+{
+	OTELC_FUNC("%p", ptr);
+
+	if (ptr == NULL)
+		OTELC_RETURN();
+
+	(void)memset(ptr, 0, sizeof(*ptr));
+	LIST_INIT(&(ptr->events));
+	LIST_INIT(&(ptr->links));
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_data_free - scope data cleanup
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_data_free(struct flt_otel_scope_data *ptr)
+ *
+ * ARGUMENTS
+ *   ptr - the scope data structure to free
+ *
+ * DESCRIPTION
+ *   Frees all contents of the scope data structure pointed to by <ptr>: baggage
+ *   and attribute key-value arrays, event entries with their attributes, link
+ *   entries, and the status description string.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_data_free(struct flt_otel_scope_data *ptr)
+{
+	struct flt_otel_scope_data_event *event, *event_back;
+	struct flt_otel_scope_data_link  *link, *link_back;
+
+	OTELC_FUNC("%p", ptr);
+
+	if (ptr == NULL)
+		OTELC_RETURN();
+
+	FLT_OTEL_DBG_SCOPE_DATA("", ptr);
+
+	/* Destroy all dynamic scope data contents. */
+	otelc_kv_destroy(&(ptr->baggage.attr), ptr->baggage.cnt);
+	otelc_kv_destroy(&(ptr->attributes.attr), ptr->attributes.cnt);
+	list_for_each_entry_safe(event, event_back, &(ptr->events), list) {
+		otelc_kv_destroy(&(event->attr), event->cnt);
+		OTELC_SFREE(event->name);
+		OTELC_SFREE(event);
+	}
+	/* Free all resolved link entries. */
+	list_for_each_entry_safe(link, link_back, &(ptr->links), list)
+		OTELC_SFREE(link);
+	OTELC_SFREE(ptr->status.description);
+
+	(void)memset(ptr, 0, sizeof(*ptr));
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_finish_mark - mark spans and contexts for finishing
+ *
+ * SYNOPSIS
+ *   int flt_otel_scope_finish_mark(const struct flt_otel_runtime_context *rt_ctx, const char *id, size_t id_len)
+ *
+ * ARGUMENTS
+ *   rt_ctx - the runtime context containing spans and contexts
+ *   id     - the target name, or a wildcard ("*", "*req*", "*res*")
+ *   id_len - length of the <id> string
+ *
+ * DESCRIPTION
+ *   Marks spans and contexts for finishing.  The <id> argument supports
+ *   wildcards: "*" marks all spans and contexts, "*req*" marks the request
+ *   channel only, "*res*" marks the response channel only.  Otherwise, a named
+ *   span or context is looked up by exact match.
+ *
+ * RETURN VALUE
+ *   Returns the number of spans and contexts that were marked.
+ */
+int flt_otel_scope_finish_mark(const struct flt_otel_runtime_context *rt_ctx, const char *id, size_t id_len)
+{
+	struct flt_otel_scope_span    *span;
+	struct flt_otel_scope_context *ctx;
+	int                            span_cnt = 0, ctx_cnt = 0, retval;
+
+	OTELC_FUNC("%p, \"%s\", %zu", rt_ctx, OTELC_STR_ARG(id), id_len);
+
+	/* Handle wildcard finish marks: all, request-only, response-only. */
+	if (FLT_OTEL_STR_CMP(FLT_OTEL_SCOPE_SPAN_FINISH_ALL, id)) {
+		list_for_each_entry(span, &(rt_ctx->spans), list) {
+			span->flag_finish = 1;
+			span_cnt++;
+		}
+
+		list_for_each_entry(ctx, &(rt_ctx->contexts), list) {
+			ctx->flag_finish = 1;
+			ctx_cnt++;
+		}
+
+		OTELC_DBG(NOTICE, "marked %d span(s), %d context(s)", span_cnt, ctx_cnt);
+	}
+	else if (FLT_OTEL_STR_CMP(FLT_OTEL_SCOPE_SPAN_FINISH_REQ, id)) {
+		list_for_each_entry(span, &(rt_ctx->spans), list)
+			if (span->smp_opt_dir == SMP_OPT_DIR_REQ) {
+				span->flag_finish = 1;
+				span_cnt++;
+			}
+
+		list_for_each_entry(ctx, &(rt_ctx->contexts), list)
+			if (ctx->smp_opt_dir == SMP_OPT_DIR_REQ) {
+				ctx->flag_finish = 1;
+				ctx_cnt++;
+			}
+
+		OTELC_DBG(NOTICE, "marked REQuest channel %d span(s), %d context(s)", span_cnt, ctx_cnt);
+	}
+	else if (FLT_OTEL_STR_CMP(FLT_OTEL_SCOPE_SPAN_FINISH_RES, id)) {
+		list_for_each_entry(span, &(rt_ctx->spans), list)
+			if (span->smp_opt_dir == SMP_OPT_DIR_RES) {
+				span->flag_finish = 1;
+				span_cnt++;
+			}
+
+		list_for_each_entry(ctx, &(rt_ctx->contexts), list)
+			if (ctx->smp_opt_dir == SMP_OPT_DIR_RES) {
+				ctx->flag_finish = 1;
+				ctx_cnt++;
+			}
+
+		OTELC_DBG(NOTICE, "marked RESponse channel %d span(s), %d context(s)", span_cnt, ctx_cnt);
+	}
+	else {
+		list_for_each_entry(span, &(rt_ctx->spans), list)
+			if (FLT_OTEL_CONF_STR_CMP(span->id, id)) {
+				span->flag_finish = 1;
+				span_cnt++;
+
+				break;
+			}
+
+		list_for_each_entry(ctx, &(rt_ctx->contexts), list)
+			if (FLT_OTEL_CONF_STR_CMP(ctx->id, id)) {
+				ctx->flag_finish = 1;
+				ctx_cnt++;
+
+				break;
+			}
+
+		if (span_cnt > 0)
+			OTELC_DBG(NOTICE, "marked span '%s'", id);
+		if (ctx_cnt > 0)
+			OTELC_DBG(NOTICE, "marked context '%s'", id);
+		if ((span_cnt + ctx_cnt) == 0)
+			OTELC_DBG(NOTICE, "cannot find span/context '%s'", id);
+	}
+
+	retval = span_cnt + ctx_cnt;
+
+	OTELC_RETURN_INT(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_finish_marked - finish marked spans and contexts
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_finish_marked(const struct flt_otel_runtime_context *rt_ctx, const struct timespec *ts_finish)
+ *
+ * ARGUMENTS
+ *   rt_ctx    - the runtime context containing spans and contexts
+ *   ts_finish - the monotonic timestamp to use as the span end time
+ *
+ * DESCRIPTION
+ *   Ends all spans and destroys all contexts that have been marked for
+ *   finishing by flt_otel_scope_finish_mark().  Each span is ended with the
+ *   <ts_finish> timestamp; each context's OTel span context is destroyed.
+ *   The finish flags are cleared after processing.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_finish_marked(const struct flt_otel_runtime_context *rt_ctx, const struct timespec *ts_finish)
+{
+	struct flt_otel_scope_span    *span;
+	struct flt_otel_scope_context *ctx;
+
+	OTELC_FUNC("%p, %p", rt_ctx, ts_finish);
+
+	/* End all spans that have been marked for finishing. */
+	list_for_each_entry(span, &(rt_ctx->spans), list)
+		if (span->flag_finish) {
+			FLT_OTEL_DBG_SCOPE_SPAN("finishing span ", span);
+
+			OTELC_OPSR(span->span, end_with_options, ts_finish, OTELC_SPAN_STATUS_IGNORE, NULL);
+
+			span->flag_finish = 0;
+		}
+
+	/* Destroy all contexts that have been marked for finishing. */
+	list_for_each_entry(ctx, &(rt_ctx->contexts), list)
+		if (ctx->flag_finish) {
+			FLT_OTEL_DBG_SCOPE_CONTEXT("finishing context ", ctx);
+
+			if (ctx->context != NULL)
+				OTELC_OPSR(ctx->context, destroy);
+
+			ctx->flag_finish = 0;
+		}
+
+	OTELC_RETURN();
+}
+
+
+/***
+ * NAME
+ *   flt_otel_scope_free_unused - remove unused spans and contexts
+ *
+ * SYNOPSIS
+ *   void flt_otel_scope_free_unused(struct flt_otel_runtime_context *rt_ctx, struct channel *chn)
+ *
+ * ARGUMENTS
+ *   rt_ctx - the runtime context to clean up
+ *   chn    - the channel for HTTP header cleanup
+ *
+ * DESCRIPTION
+ *   Removes scope spans with a NULL OTel span and scope contexts with a NULL
+ *   OTel context from the runtime context.  For each removed context, the
+ *   associated HTTP headers and HAProxy variables are also cleaned up via
+ *   <chn>.
+ *
+ * RETURN VALUE
+ *   This function does not return a value.
+ */
+void flt_otel_scope_free_unused(struct flt_otel_runtime_context *rt_ctx, struct channel *chn)
+{
+	OTELC_FUNC("%p, %p", rt_ctx, chn);
+
+	if (rt_ctx == NULL)
+		OTELC_RETURN();
+
+	/* Remove spans that were never successfully created. */
+	if (!LIST_ISEMPTY(&(rt_ctx->spans))) {
+		struct flt_otel_scope_span *span, *span_back;
+
+		list_for_each_entry_safe(span, span_back, &(rt_ctx->spans), list)
+			if (span->span == NULL)
+				flt_otel_scope_span_free(&span);
+	}
+
+	/* Remove contexts that failed extraction and clean up their traces. */
+	if (!LIST_ISEMPTY(&(rt_ctx->contexts))) {
+		struct flt_otel_scope_context *ctx, *ctx_back;
+
+		list_for_each_entry_safe(ctx, ctx_back, &(rt_ctx->contexts), list)
+			if (ctx->context == NULL) {
+				/*
+				 * All headers and variables associated with
+				 * the context in question should be deleted.
+				 */
+				(void)flt_otel_http_headers_remove(chn, ctx->id, NULL);
+#ifdef USE_OTEL_VARS
+				(void)flt_otel_vars_unset(rt_ctx->stream, FLT_OTEL_VARS_SCOPE, ctx->id, ctx->smp_opt_dir, NULL);
+#endif
+
+				flt_otel_scope_context_free(&ctx);
+			}
+	}
+
+	FLT_OTEL_DBG_RUNTIME_CONTEXT("session context: ", rt_ctx);
+
+	OTELC_RETURN();
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */

addons/otel/test/README-cmp

@@ -0,0 +1,85 @@
+Comparison test configuration (cmp/)
+====================================
+
+The 'cmp' test is a simplified standalone configuration made for comparison with
+other tracing implementations.  It uses a reduced set of events and a compact
+span hierarchy without context propagation, groups or metrics.  This
+configuration is closer to a typical production deployment.
+
+All response-side scopes (http_response, http_response-error, server_session_end
+and client_session_end) share the on-http-response event, which means they fire
+in a single batch at response time.
+
+
+Files
+-----
+
+  cmp/otel.cfg    OTel filter configuration (scopes)
+  cmp/haproxy.cfg HAProxy frontend/backend configuration
+  cmp/otel.yml    Exporter, processor, reader and provider definitions
+  run-cmp.sh      Convenience script to launch HAProxy with this config
+
+
+Events
+------
+
+  T = Trace (span)
+
+  This configuration produces traces only -- no metrics or log-records.
+
+  Request analyzer events:
+
+    Event                      Scope                    T
+    --------------------------------------------------------
+    on-client-session-start    client_session_start     x
+    on-frontend-tcp-request    frontend_tcp_request     x
+    on-frontend-http-request   frontend_http_request    x
+    on-backend-tcp-request     backend_tcp_request      x
+    on-backend-http-request    backend_http_request     x
+    on-server-unavailable      server_unavailable       x
+
+  Response analyzer events:
+
+    Event                      Scope                    T
+    --------------------------------------------------------
+    on-server-session-start    server_session_start     x
+    on-tcp-response            tcp_response             x
+    on-http-response           http_response            x
+    on-http-response           http_response-error      x  (conditional)
+    on-http-response           server_session_end       -  (finish only)
+    on-http-response           client_session_end       -  (finish only)
+
+  The http_response-error scope fires conditionally when the ACL
+  acl-http-status-ok (status 100:399) does not match, setting an error status
+  on the "HTTP response" span.
+
+  The server_session_end and client_session_end scopes are bound to the
+  on-http-response event and only perform finish operations.
+
+
+Span hierarchy
+--------------
+
+    "HAProxy session" (root)
+     +-- "Client session"
+          +-- "Frontend TCP request"
+               +-- "Frontend HTTP request"
+                    +-- "Backend TCP request"
+                         +-- "Backend HTTP request"
+
+    "HAProxy session" (root)
+     +-- "Server session"
+          +-- "TCP response"
+               +-- "HTTP response"
+
+
+Running the test
+----------------
+
+From the test/ directory:
+
+  % ./run-cmp.sh [/path/to/haproxy] [pidfile]
+
+If no arguments are given, the script looks for the haproxy binary three
+directories up from the current working directory.  The backend origin server
+must be running on 127.0.0.1:8000.

addons/otel/test/README-ctx

@@ -0,0 +1,149 @@
+Context propagation test configuration (ctx/)
+=============================================
+
+The 'ctx' test is a standalone configuration that uses inject/extract context
+propagation on every scope.  Spans are opened using extracted span contexts
+stored in HAProxy variables as parent references instead of direct span names.
+This adds the overhead of context serialization, variable storage and
+deserialization on every scope execution.
+
+The event coverage matches the 'sa' configuration.  The key difference is the
+propagation mechanism: each scope injects its context into a numbered variable
+(otel_ctx_1 through otel_ctx_17) and the next scope extracts from that variable
+to establish the parent relationship.
+
+The client_session_start event is split into two scopes (client_session_start_1
+and client_session_start_2) to demonstrate inject/extract between scopes
+handling the same event.
+
+
+Files
+-----
+
+  ctx/otel.cfg    OTel filter configuration (scopes, groups, contexts)
+  ctx/haproxy.cfg HAProxy frontend/backend configuration
+  ctx/otel.yml    Exporter, processor, reader and provider definitions
+  run-ctx.sh      Convenience script to launch HAProxy with this config
+
+
+Events
+------
+
+  T = Trace (span)
+
+  This configuration produces traces only -- no metrics or log-records.
+
+  Stream lifecycle events:
+
+    Event                    Scope                        T
+    ----------------------------------------------------------
+    on-client-session-start  client_session_start_1       x
+    on-client-session-start  client_session_start_2       x
+
+  Request analyzer events:
+
+    Event                              Scope                          T
+    --------------------------------------------------------------------
+    on-frontend-tcp-request            frontend_tcp_request           x
+    on-http-wait-request               http_wait_request              x
+    on-http-body-request               http_body_request              x
+    on-frontend-http-request           frontend_http_request          x
+    on-switching-rules-request         switching_rules_request        x
+    on-backend-tcp-request             backend_tcp_request            x
+    on-backend-http-request            backend_http_request           x
+    on-process-server-rules-request    process_server_rules_request   x
+    on-http-process-request            http_process_request           x
+    on-tcp-rdp-cookie-request          tcp_rdp_cookie_request         x
+    on-process-sticking-rules-request  process_sticking_rules_request x
+    on-client-session-end              client_session_end             -
+    on-server-unavailable              server_unavailable             -
+
+  Response analyzer events:
+
+    Event                              Scope                          T
+    --------------------------------------------------------------------
+    on-server-session-start            server_session_start           x
+    on-tcp-response                    tcp_response                   x
+    on-http-wait-response              http_wait_response             x
+    on-process-store-rules-response    process_store_rules_response   x
+    on-http-response                   http_response                  x
+    on-http-response                   http_response-error            x  (conditional)
+    on-server-session-end              server_session_end             -
+
+  The http_response_group (http_response_1, http_response_2) and
+  http_after_response_group (http_after_response) are invoked via http-response
+  and http-after-response directives in haproxy.cfg.
+
+
+Context propagation chain
+-------------------------
+
+  Each scope injects its span context into a HAProxy variable and the next scope
+  extracts it.  The variable names and their flow:
+
+    otel_ctx_1   "HAProxy session"              -> client_session_start_2
+    otel_ctx_2   "Client session"               -> frontend_tcp_request
+    otel_ctx_3   "Frontend TCP request"         -> http_wait_request
+    otel_ctx_4   "HTTP wait request"            -> http_body_request
+    otel_ctx_5   "HTTP body request"            -> frontend_http_request
+    otel_ctx_6   "Frontend HTTP request"        -> switching_rules_request
+    otel_ctx_7   "Switching rules request"      -> backend_tcp_request
+    otel_ctx_8   "Backend TCP request"          -> backend_http_request
+    otel_ctx_9   "Backend HTTP request"         -> process_server_rules_request
+    otel_ctx_10  "Process server rules request" -> http_process_request
+    otel_ctx_11  "HTTP process request"         -> tcp_rdp_cookie_request
+    otel_ctx_12  "TCP RDP cookie request"       -> process_sticking_rules_request
+    otel_ctx_13  "Process sticking rules req."  -> server_session_start
+    otel_ctx_14  "Server session"               -> tcp_response
+    otel_ctx_15  "TCP response"                 -> http_wait_response
+    otel_ctx_16  "HTTP wait response"           -> process_store_rules_response
+    otel_ctx_17  "Process store rules response" -> http_response
+
+  All contexts use both use-headers and use-vars injection modes, except
+  otel_ctx_14 and otel_ctx_15 which use use-vars only.
+
+
+Span hierarchy
+--------------
+
+  The span hierarchy is identical to the 'sa' configuration, but parent
+  relationships are established through extracted contexts rather than direct
+  span name references.
+
+  Request path:
+
+    "HAProxy session" (root)                                   [otel_ctx_1]
+     +-- "Client session"                                      [otel_ctx_2]
+          +-- "Frontend TCP request"                           [otel_ctx_3]
+               +-- "HTTP wait request"                         [otel_ctx_4]
+                    +-- "HTTP body request"                    [otel_ctx_5]
+                         +-- "Frontend HTTP request"           [otel_ctx_6]
+                              +-- "Switching rules request"    [otel_ctx_7]
+                                   +-- "Backend TCP request"   [otel_ctx_8]
+                                        +-- (continues to process_sticking_rules_request)
+
+  Response path:
+
+    "HAProxy session"                                          [otel_ctx_1]
+     +-- "Server session"                                      [otel_ctx_14]
+          +-- "TCP response"                                   [otel_ctx_15]
+               +-- "HTTP wait response"                        [otel_ctx_16]
+                    +-- "Process store rules response"         [otel_ctx_17]
+                         +-- "HTTP response"
+
+  Auxiliary spans:
+
+    "HAProxy session"
+     +-- "HAProxy response"       (http_after_response_group, on error)
+
+
+Running the test
+----------------
+
+From the test/ directory:
+
+  % ./run-ctx.sh [/path/to/haproxy] [pidfile]
+
+If no arguments are given, the script looks for the haproxy binary three
+directories up from the current working directory.  The backend origin server
+must be running on 127.0.0.1:8000.

addons/otel/test/README-empty

@@ -0,0 +1,53 @@
+Empty test configuration (empty/)
+=================================
+
+The 'empty' test is a minimal configuration that loads the OTel filter without
+defining any scopes, events or groups.  The instrumentation block contains only
+the config directive pointing to the YAML pipeline definition.
+
+This configuration verifies that the filter initializes and shuts down cleanly
+when no telemetry is configured.  It exercises the full YAML parsing path
+(exporters, processors, readers, samplers, providers and signals) without
+producing any trace, metric or log-record data.
+
+
+Files
+-----
+
+  empty/otel.cfg    OTel filter configuration (instrumentation only)
+  empty/haproxy.cfg HAProxy frontend/backend configuration
+  empty/otel.yml    Exporter, processor, reader and provider definitions
+
+
+Events
+------
+
+  No events are registered.  The filter is loaded and attached to the frontend
+  but performs no per-stream processing.
+
+
+YAML pipeline
+-------------
+
+  Despite the empty filter configuration, the otel.yml file defines a complete
+  pipeline with all three signal types to verify that the YAML parser handles
+  the full configuration without errors:
+
+    Signal     Exporter                   Processor / Reader
+    -----------------------------------------------------------
+    traces     exporter_traces_otlp_http  processor_traces_batch
+    metrics    exporter_metrics_otlp_http reader_metrics
+    logs       exporter_logs_otlp_http    processor_logs_batch
+
+  Additional exporter definitions (otlp_file, otlp_grpc, ostream, memory,
+  zipkin, elasticsearch) are present in the YAML but are not wired into the
+  active signal pipelines.
+
+
+Running the test
+----------------
+
+There is no dedicated run script for the empty configuration.  To run it
+manually from the test/ directory:
+
+  % /path/to/haproxy -f haproxy-common.cfg -f empty/haproxy.cfg

addons/otel/test/README-fe-be

@@ -0,0 +1,124 @@
+Frontend / backend test configuration (fe/ + be/)
+=================================================
+
+The 'fe-be' test uses two cascaded HAProxy instances to demonstrate
+inter-process trace context propagation via HTTP headers.  The frontend instance
+(fe/) creates the root trace and injects span context into the HTTP request
+headers.  The backend instance (be/) extracts that context and continues the
+trace as a child of the frontend's span.
+
+The two instances run as separate processes: the frontend listens on port 10080
+and proxies to the backend on port 11080, which in turn proxies to the origin
+server on port 8000.
+
+
+Files
+-----
+
+  fe/otel.cfg    OTel filter configuration for the frontend instance
+  fe/haproxy.cfg HAProxy configuration for the frontend instance
+  be/otel.cfg    OTel filter configuration for the backend instance
+  be/haproxy.cfg HAProxy configuration for the backend instance
+  run-fe-be.sh   Convenience script to launch both instances
+
+
+Events
+------
+
+  T = Trace (span)
+
+  Both instances produce traces only -- no metrics or log-records.
+
+  Frontend (fe/) events:
+
+    Event                      Scope                    T
+    --------------------------------------------------------
+    on-client-session-start    client_session_start     x
+    on-frontend-tcp-request    frontend_tcp_request     x
+    on-frontend-http-request   frontend_http_request    x
+    on-backend-tcp-request     backend_tcp_request      x
+    on-backend-http-request    backend_http_request     x
+    on-client-session-end      client_session_end       -
+    on-server-session-start    server_session_start     x
+    on-tcp-response            tcp_response             x
+    on-http-response           http_response            x
+    on-server-session-end      server_session_end       -
+
+  Backend (be/) events:
+
+    Event                      Scope                    T
+    --------------------------------------------------------
+    on-frontend-http-request   frontend_http_request    x
+    on-backend-tcp-request     backend_tcp_request      x
+    on-backend-http-request    backend_http_request     x
+    on-client-session-end      client_session_end       -
+    on-server-session-start    server_session_start     x
+    on-tcp-response            tcp_response             x
+    on-http-response           http_response            x
+    on-server-session-end      server_session_end       -
+
+  The backend starts its trace at on-frontend-http-request where it extracts
+  the span context injected by the frontend.  Earlier request events
+  (on-client-session-start, on-frontend-tcp-request) are not needed because
+  the context is not yet available in the HTTP headers at that point.
+
+
+Context propagation
+-------------------
+
+  The frontend injects context into HTTP headers in the backend_http_request
+  scope:
+
+    span "HAProxy session"
+        inject "otel-ctx" use-headers
+
+  The backend extracts that context in its frontend_http_request scope:
+
+    extract "otel-ctx" use-headers
+    span "HAProxy session" parent "otel-ctx" root
+
+
+Span hierarchy
+--------------
+
+  Frontend (fe/):
+
+    "HAProxy session" (root)
+     +-- "Client session"
+          +-- "Frontend TCP request"
+               +-- "Frontend HTTP request"
+                    +-- "Backend TCP request"
+                         +-- "Backend HTTP request"
+
+    "HAProxy session" (root)
+     +-- "Server session"
+          +-- "TCP response"
+               +-- "HTTP response"
+
+  Backend (be/):
+
+    "HAProxy session" (root, parent: frontend's "HAProxy session")
+     +-- "Client session"
+          +-- "Frontend HTTP request"
+               +-- "Backend TCP request"
+                    +-- "Backend HTTP request"
+
+    "HAProxy session" (root)
+     +-- "Server session"
+          +-- "TCP response"
+               +-- "HTTP response"
+
+
+Running the test
+----------------
+
+From the test/ directory:
+
+  % ./run-fe-be.sh [/path/to/haproxy] [pidfile]
+
+If no arguments are given, the script looks for the haproxy binary three
+directories up from the current working directory.  The backend origin server
+must be running on 127.0.0.1:8000.
+
+The script launches both HAProxy instances in the background and waits.
+Press CTRL-C to stop both instances.

addons/otel/test/README-full

@@ -0,0 +1,158 @@
+Full event coverage test configuration (full/)
+==============================================
+
+The 'full' test is a standalone single-instance configuration that exercises
+every supported OTel filter event with all three signal types: traces (spans),
+metrics (instruments) and logs (log-records).
+
+It extends the 'sa' (standalone) configuration by adding the events that 'sa'
+does not cover and by attaching log-records to every scope.
+
+
+Files
+-----
+
+  full/otel.cfg    OTel filter configuration (scopes, groups, instruments)
+  full/haproxy.cfg HAProxy frontend/backend configuration
+  full/otel.yml    Exporter, processor, reader and provider definitions
+  run-full.sh      Convenience script to launch HAProxy with this config
+
+
+Events
+------
+
+The table below lists every event defined in include/event.h together with the
+scope that handles it and the signals produced by that scope.
+
+  T = Trace (span)    M = Metric (instrument)    L = Log (log-record)
+
+  Stream lifecycle events:
+
+    Event                    Scope                       T  M  L
+    ---------------------------------------------------------------
+    on-stream-start          on_stream_start             x  x  x
+    on-stream-stop           on_stream_stop              -  -  x
+    on-idle-timeout          on_idle_timeout              x  x  x
+    on-backend-set           on_backend_set               x  x  x
+
+  Request analyzer events:
+
+    Event                              Scope                          T  M  L
+    --------------------------------------------------------------------------
+    on-client-session-start            client_session_start           x  x  x
+    on-frontend-tcp-request            frontend_tcp_request           x  x  x
+    on-http-wait-request               http_wait_request              x  -  x
+    on-http-body-request               http_body_request              x  -  x
+    on-frontend-http-request           frontend_http_request          x  x  x
+    on-switching-rules-request         switching_rules_request        x  -  x
+    on-backend-tcp-request             backend_tcp_request            x  x  x
+    on-backend-http-request            backend_http_request           x  -  x
+    on-process-server-rules-request    process_server_rules_request   x  -  x
+    on-http-process-request            http_process_request           x  -  x
+    on-tcp-rdp-cookie-request          tcp_rdp_cookie_request         x  -  x
+    on-process-sticking-rules-request  process_sticking_rules_request x  -  x
+    on-http-headers-request            http_headers_request           x  x  x
+    on-http-end-request                http_end_request               x  x  x
+    on-client-session-end              client_session_end             -  x  x
+    on-server-unavailable              server_unavailable             -  -  x
+
+  Response analyzer events:
+
+    Event                              Scope                          T  M  L
+    --------------------------------------------------------------------------
+    on-server-session-start            server_session_start           x  x  x
+    on-tcp-response                    tcp_response                   x  x  x
+    on-http-wait-response              http_wait_response             x  -  x
+    on-process-store-rules-response    process_store_rules_response   x  -  x
+    on-http-response                   http_response                  x  x  x
+    on-http-headers-response           http_headers_response          x  x  x
+    on-http-end-response               http_end_response              x  x  x
+    on-http-reply                      http_reply                     x  x  x
+    on-server-session-end              server_session_end             -  x  x
+
+  Additionally, the http_response-error scope fires conditionally on the
+  on-http-response event when the response status is outside the 100-399 range,
+  setting an error status on the "HTTP response" span.
+
+  The http_response_group (http_response_1, http_response_2) and
+  http_after_response_group (http_after_response) are invoked via http-response
+  and http-after-response directives in haproxy.cfg.
+
+
+Instruments
+-----------
+
+Every instrument definition has at least one corresponding update.
+
+  Instrument name                Type       Defined in              Updated in
+  -------------------------------------------------------------------------------
+  haproxy.sessions.active        udcnt_int  on_stream_start         client_session_end
+  haproxy.fe.connections         gauge_int  on_stream_start         http_response
+  idle.count                     cnt_int    on_idle_timeout         on_idle_timeout
+  haproxy.backend.set            cnt_int    on_backend_set          on_backend_set
+  haproxy.client.session.start   cnt_int    client_session_start    client_session_end
+  haproxy.tcp.request.fe         cnt_int    frontend_tcp_request    frontend_http_request
+  haproxy.http.requests          cnt_int    frontend_http_request   http_response
+  haproxy.http.latency           hist_int   frontend_http_request   frontend_http_request,
+                                                                    http_response
+  haproxy.tcp.request.be         cnt_int    backend_tcp_request     backend_http_request
+  haproxy.http.headers.request   cnt_int    http_headers_request    http_end_request
+  haproxy.http.end.request       cnt_int    http_end_request        client_session_end
+  haproxy.server.session.start   cnt_int    server_session_start    server_session_end
+  haproxy.tcp.response           cnt_int    tcp_response            http_wait_response
+  haproxy.http.headers.response  cnt_int    http_headers_response   http_end_response
+  haproxy.http.end.response      cnt_int    http_end_response       http_reply
+  haproxy.http.reply             cnt_int    http_reply              server_session_end
+
+
+Span hierarchy
+--------------
+
+  Request path:
+
+    "HAProxy session" (root)
+     +-- "Client session"
+          +-- "Frontend TCP request"
+               +-- "HTTP wait request"
+                    +-- "HTTP body request"
+                         +-- "Frontend HTTP request"  [link: "HAProxy session"]
+                              +-- "Switching rules request"
+                                   +-- "Backend TCP request"
+                                        +-- "Backend HTTP request"
+                                             +-- "Process server rules request"
+                                                  +-- "HTTP process request"
+                                                       +-- "TCP RDP cookie request"
+                                                            +-- "Process sticking rules request"
+                                                                 +-- "HTTP headers request"
+                                                                      +-- "HTTP end request"
+
+  Response path:
+
+    "HAProxy session" (root)
+     +-- "Server session"  [link: "HAProxy session", "Client session"]
+          +-- "TCP response"
+               +-- "HTTP wait response"
+                    +-- "Process store rules response"
+                         +-- "HTTP response"
+                              +-- "HTTP headers response"
+                                   +-- "HTTP end response"
+                                        +-- "HTTP reply"
+
+  Auxiliary spans:
+
+    "HAProxy session"
+     +-- "Backend set"
+     +-- "heartbeat"              (on-idle-timeout, periodic)
+     +-- "HAProxy response"       (http_after_response_group, on error)
+
+
+Running the test
+----------------
+
+From the test/ directory:
+
+  % ./run-full.sh [/path/to/haproxy] [pidfile]
+
+If no arguments are given, the script looks for the haproxy binary three
+directories up from the current working directory.  The backend origin server
+must be running on 127.0.0.1:8000.

addons/otel/test/README-sa

@@ -0,0 +1,134 @@
+Standalone test configuration (sa/)
+=====================================
+
+The 'sa' test is a standalone single-instance configuration that
+exercises most HAProxy filter events with spans, attributes, events,
+links, baggage, status, metrics, logs and groups.  It represents the
+most comprehensive single-instance configuration and is used as the
+worst-case scenario in speed tests.
+
+Six events are not covered by this configuration: on-backend-set,
+on-http-headers-request, on-http-end-request, on-http-headers-response,
+on-http-end-response and on-http-reply.  The 'full' configuration
+extends 'sa' with those events.
+
+
+Files
+------
+
+  sa/otel.cfg    OTel filter configuration (scopes, groups, instruments)
+  sa/haproxy.cfg HAProxy frontend/backend configuration
+  sa/otel.yml    Exporter, processor, reader and provider definitions
+  run-sa.sh      Convenience script to launch HAProxy with this config
+
+
+Events
+-------
+
+  T = Trace (span)    M = Metric (instrument)    L = Log (log-record)
+
+  Stream lifecycle events:
+
+    Event                    Scope                       T  M  L
+    ---------------------------------------------------------------
+    on-stream-start          on_stream_start             x  x  x
+    on-stream-stop           on_stream_stop              -  -  -
+    on-idle-timeout          on_idle_timeout              x  x  x
+
+  Request analyzer events:
+
+    Event                              Scope                          T  M  L
+    --------------------------------------------------------------------------
+    on-client-session-start            client_session_start           x  -  -
+    on-frontend-tcp-request            frontend_tcp_request           x  -  -
+    on-http-wait-request               http_wait_request              x  -  -
+    on-http-body-request               http_body_request              x  -  -
+    on-frontend-http-request           frontend_http_request          x  x  x
+    on-switching-rules-request         switching_rules_request        x  -  -
+    on-backend-tcp-request             backend_tcp_request            x  -  -
+    on-backend-http-request            backend_http_request           x  -  -
+    on-process-server-rules-request    process_server_rules_request   x  -  -
+    on-http-process-request            http_process_request           x  -  -
+    on-tcp-rdp-cookie-request          tcp_rdp_cookie_request         x  -  -
+    on-process-sticking-rules-request  process_sticking_rules_request x  -  -
+    on-client-session-end              client_session_end             -  x  -
+    on-server-unavailable              server_unavailable             -  -  -
+
+  Response analyzer events:
+
+    Event                              Scope                          T  M  L
+    --------------------------------------------------------------------------
+    on-server-session-start            server_session_start           x  -  -
+    on-tcp-response                    tcp_response                   x  -  -
+    on-http-wait-response              http_wait_response             x  -  -
+    on-process-store-rules-response    process_store_rules_response   x  -  -
+    on-http-response                   http_response                  x  x  -
+    on-server-session-end              server_session_end             -  -  -
+
+  Additionally, the http_response-error scope fires conditionally on the
+  on-http-response event when the response status is outside the 100-399
+  range, setting an error status on the "HTTP response" span.
+
+  The http_response_group (http_response_1, http_response_2) and
+  http_after_response_group (http_after_response) are invoked via
+  http-response and http-after-response directives in haproxy.cfg.
+
+
+Instruments
+------------
+
+  Instrument name            Type       Defined in              Updated in
+  --------------------------------------------------------------------------
+  haproxy.sessions.active    udcnt_int  on_stream_start         client_session_end
+  haproxy.fe.connections     gauge_int  on_stream_start         http_response
+  idle.count                 cnt_int    on_idle_timeout         on_idle_timeout
+  haproxy.http.requests      cnt_int    frontend_http_request   http_response
+  haproxy.http.latency       hist_int   frontend_http_request   frontend_http_request,
+                                                                http_response
+
+
+Span hierarchy
+---------------
+
+  Request path:
+
+    "HAProxy session" (root)
+     +-- "Client session"
+          +-- "Frontend TCP request"
+               +-- "HTTP wait request"
+                    +-- "HTTP body request"
+                         +-- "Frontend HTTP request"  [link: "HAProxy session"]
+                              +-- "Switching rules request"
+                                   +-- "Backend TCP request"
+                                        +-- "Backend HTTP request"
+                                             +-- "Process server rules request"
+                                                  +-- "HTTP process request"
+                                                       +-- "TCP RDP cookie request"
+                                                            +-- "Process sticking rules request"
+
+  Response path:
+
+    "HAProxy session" (root)
+     +-- "Server session"  [link: "HAProxy session", "Client session"]
+          +-- "TCP response"
+               +-- "HTTP wait response"
+                    +-- "Process store rules response"
+                         +-- "HTTP response"
+
+  Auxiliary spans:
+
+    "HAProxy session"
+     +-- "heartbeat"              (on-idle-timeout, periodic)
+     +-- "HAProxy response"       (http_after_response_group, on error)
+
+
+Running the test
+-----------------
+
+From the test/ directory:
+
+  % ./run-sa.sh [/path/to/haproxy] [pidfile]
+
+If no arguments are given, the script looks for the haproxy binary three
+directories up from the current working directory.  The backend origin
+server must be running on 127.0.0.1:8000.

addons/otel/test/README-speed-cmp

@@ -0,0 +1,144 @@
+--- rate-limit 100.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   182.58us  129.11us  16.19ms   98.11%
+    Req/Sec     5.63k   240.83     6.29k    69.74%
+  Latency Distribution
+     50%  169.00us
+     75%  183.00us
+     90%  209.00us
+     99%  367.00us
+  13438310 requests in 5.00m, 3.24GB read
+Requests/sec:  44779.51
+Transfer/sec:     11.06MB
+----------------------------------------------------------------------
+
+--- rate-limit 75.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   180.10us  122.51us  14.57ms   98.00%
+    Req/Sec     5.70k   253.08     6.28k    70.41%
+  Latency Distribution
+     50%  169.00us
+     75%  184.00us
+     90%  206.00us
+     99%  362.00us
+  13613023 requests in 5.00m, 3.28GB read
+Requests/sec:  45361.63
+Transfer/sec:     11.20MB
+----------------------------------------------------------------------
+
+--- rate-limit 50.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   176.59us  125.34us  15.58ms   98.02%
+    Req/Sec     5.81k   230.84     6.42k    72.14%
+  Latency Distribution
+     50%  166.00us
+     75%  182.00us
+     90%  202.00us
+     99%  361.00us
+  13888448 requests in 5.00m, 3.35GB read
+Requests/sec:  46279.45
+Transfer/sec:     11.43MB
+----------------------------------------------------------------------
+
+--- rate-limit 25.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   173.57us  118.35us  13.12ms   97.91%
+    Req/Sec     5.91k   257.69     6.46k    66.83%
+  Latency Distribution
+     50%  162.00us
+     75%  178.00us
+     90%  199.00us
+     99%  362.00us
+  14122906 requests in 5.00m, 3.41GB read
+Requests/sec:  47060.71
+Transfer/sec:     11.62MB
+----------------------------------------------------------------------
+
+--- rate-limit 10.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   170.85us  112.24us  10.72ms   97.84%
+    Req/Sec     6.00k   269.81     8.10k    69.46%
+  Latency Distribution
+     50%  159.00us
+     75%  172.00us
+     90%  194.00us
+     99%  361.00us
+  14342642 requests in 5.00m, 3.46GB read
+Requests/sec:  47792.96
+Transfer/sec:     11.80MB
+----------------------------------------------------------------------
+
+--- rate-limit 2.5 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   169.11us  127.52us  16.90ms   98.06%
+    Req/Sec     6.08k   261.57     6.55k    67.30%
+  Latency Distribution
+     50%  158.00us
+     75%  168.00us
+     90%  186.00us
+     99%  367.00us
+  14527714 requests in 5.00m, 3.50GB read
+Requests/sec:  48409.62
+Transfer/sec:     11.96MB
+----------------------------------------------------------------------
+
+--- rate-limit 0.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.09us  108.96us   9.07ms   97.81%
+    Req/Sec     6.10k   284.22     6.55k    70.65%
+  Latency Distribution
+     50%  157.00us
+     75%  167.00us
+     90%  184.00us
+     99%  362.00us
+  14580762 requests in 5.00m, 3.52GB read
+Requests/sec:  48586.42
+Transfer/sec:     12.00MB
+----------------------------------------------------------------------
+
+--- rate-limit disabled --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.57us  118.05us  13.51ms   97.94%
+    Req/Sec     6.09k   251.47     6.99k    67.33%
+  Latency Distribution
+     50%  158.00us
+     75%  167.00us
+     90%  184.00us
+     99%  363.00us
+  14557824 requests in 5.00m, 3.51GB read
+Requests/sec:  48509.96
+Transfer/sec:     11.98MB
+----------------------------------------------------------------------
+
+--- rate-limit off --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.64us  120.15us  14.49ms   98.01%
+    Req/Sec     6.09k   267.94     6.57k    66.19%
+  Latency Distribution
+     50%  158.00us
+     75%  167.00us
+     90%  184.00us
+     99%  361.00us
+  14551312 requests in 5.00m, 3.51GB read
+Requests/sec:  48488.23
+Transfer/sec:     11.98MB
+----------------------------------------------------------------------
+

addons/otel/test/README-speed-ctx

@@ -0,0 +1,144 @@
+--- rate-limit 100.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   270.35us  136.92us  16.02ms   97.98%
+    Req/Sec     3.77k   217.57     5.33k    67.74%
+  Latency Distribution
+     50%  264.00us
+     75%  287.00us
+     90%  309.00us
+     99%  494.00us
+  9012538 requests in 5.00m, 2.17GB read
+Requests/sec:  30031.85
+Transfer/sec:      7.42MB
+----------------------------------------------------------------------
+
+--- rate-limit 75.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   242.56us  131.47us   9.82ms   94.77%
+    Req/Sec     4.21k   218.42     5.61k    68.12%
+  Latency Distribution
+     50%  246.00us
+     75%  279.00us
+     90%  308.00us
+     99%  464.00us
+  10050409 requests in 5.00m, 2.42GB read
+Requests/sec:  33490.26
+Transfer/sec:      8.27MB
+----------------------------------------------------------------------
+
+--- rate-limit 50.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   215.92us  130.82us   9.93ms   96.81%
+    Req/Sec     4.73k   243.84     7.13k    67.13%
+  Latency Distribution
+     50%  208.00us
+     75%  264.00us
+     90%  300.00us
+     99%  439.00us
+  11307386 requests in 5.00m, 2.73GB read
+Requests/sec:  37678.82
+Transfer/sec:      9.31MB
+----------------------------------------------------------------------
+
+--- rate-limit 25.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   192.36us  132.47us  13.75ms   96.79%
+    Req/Sec     5.33k   260.46     6.17k    66.30%
+  Latency Distribution
+     50%  166.00us
+     75%  227.00us
+     90%  280.00us
+     99%  407.00us
+  12734770 requests in 5.00m, 3.07GB read
+Requests/sec:  42448.91
+Transfer/sec:     10.48MB
+----------------------------------------------------------------------
+
+--- rate-limit 10.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   180.08us  127.35us  13.34ms   97.06%
+    Req/Sec     5.71k   272.98     6.40k    67.94%
+  Latency Distribution
+     50%  161.00us
+     75%  183.00us
+     90%  250.00us
+     99%  386.00us
+  13641901 requests in 5.00m, 3.29GB read
+Requests/sec:  45457.92
+Transfer/sec:     11.23MB
+----------------------------------------------------------------------
+
+--- rate-limit 2.5 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   171.64us  107.08us   5.69ms   96.57%
+    Req/Sec     5.97k   289.99     6.55k    68.53%
+  Latency Distribution
+     50%  159.00us
+     75%  171.00us
+     90%  195.00us
+     99%  372.00us
+  14268464 requests in 5.00m, 3.44GB read
+Requests/sec:  47545.77
+Transfer/sec:     11.74MB
+----------------------------------------------------------------------
+
+--- rate-limit 0.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.86us  104.53us   5.75ms   97.73%
+    Req/Sec     6.07k   282.19     6.59k    67.47%
+  Latency Distribution
+     50%  158.00us
+     75%  168.00us
+     90%  186.00us
+     99%  361.00us
+  14498699 requests in 5.00m, 3.50GB read
+Requests/sec:  48312.96
+Transfer/sec:     11.93MB
+----------------------------------------------------------------------
+
+--- rate-limit disabled --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.36us  129.52us  17.68ms   98.13%
+    Req/Sec     6.11k   263.70     6.83k    70.42%
+  Latency Distribution
+     50%  157.00us
+     75%  167.00us
+     90%  183.00us
+     99%  363.00us
+  14590953 requests in 5.00m, 3.52GB read
+Requests/sec:  48620.36
+Transfer/sec:     12.01MB
+----------------------------------------------------------------------
+
+--- rate-limit off --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.73us  120.51us  15.03ms   98.02%
+    Req/Sec     6.09k   270.88     6.55k    68.99%
+  Latency Distribution
+     50%  158.00us
+     75%  167.00us
+     90%  185.00us
+     99%  360.00us
+  14538507 requests in 5.00m, 3.51GB read
+Requests/sec:  48445.53
+Transfer/sec:     11.97MB
+----------------------------------------------------------------------
+

addons/otel/test/README-speed-fe-be

@@ -0,0 +1,144 @@
+--- rate-limit 100.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   238.75us  129.45us  15.59ms   98.45%
+    Req/Sec     4.27k    75.22     5.28k    77.45%
+  Latency Distribution
+     50%  228.00us
+     75%  243.00us
+     90%  262.00us
+     99%  410.00us
+  10206938 requests in 5.00m, 2.46GB read
+Requests/sec:  34011.80
+Transfer/sec:      8.40MB
+----------------------------------------------------------------------
+
+--- rate-limit 75.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   230.08us  201.50us  32.12ms   99.25%
+    Req/Sec     4.46k    83.43     5.36k    75.61%
+  Latency Distribution
+     50%  222.00us
+     75%  241.00us
+     90%  261.00us
+     99%  401.00us
+  10641998 requests in 5.00m, 2.57GB read
+Requests/sec:  35461.59
+Transfer/sec:      8.76MB
+----------------------------------------------------------------------
+
+--- rate-limit 50.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   222.33us  242.52us  35.13ms   99.43%
+    Req/Sec     4.62k    99.86     5.78k    79.00%
+  Latency Distribution
+     50%  211.00us
+     75%  237.00us
+     90%  259.00us
+     99%  400.00us
+  11046951 requests in 5.00m, 2.66GB read
+Requests/sec:  36810.91
+Transfer/sec:      9.09MB
+----------------------------------------------------------------------
+
+--- rate-limit 25.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   210.95us  117.20us  10.57ms   97.85%
+    Req/Sec     4.84k   101.85     6.04k    68.10%
+  Latency Distribution
+     50%  198.00us
+     75%  222.00us
+     90%  252.00us
+     99%  394.00us
+  11551741 requests in 5.00m, 2.79GB read
+Requests/sec:  38493.03
+Transfer/sec:      9.51MB
+----------------------------------------------------------------------
+
+--- rate-limit 10.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   206.15us  209.34us  31.73ms   99.27%
+    Req/Sec     4.99k   112.62     5.36k    71.21%
+  Latency Distribution
+     50%  193.00us
+     75%  210.00us
+     90%  237.00us
+     99%  387.00us
+  11924489 requests in 5.00m, 2.88GB read
+Requests/sec:  39735.09
+Transfer/sec:      9.81MB
+----------------------------------------------------------------------
+
+--- rate-limit 2.5 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   202.35us  180.56us  27.28ms   99.10%
+    Req/Sec     5.08k   145.06     8.27k    71.24%
+  Latency Distribution
+     50%  191.00us
+     75%  205.00us
+     90%  223.00us
+     99%  374.00us
+  12131047 requests in 5.00m, 2.93GB read
+Requests/sec:  40423.43
+Transfer/sec:      9.98MB
+----------------------------------------------------------------------
+
+--- rate-limit 0.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   200.88us  223.19us  32.70ms   99.44%
+    Req/Sec     5.13k   151.03     6.55k    69.46%
+  Latency Distribution
+     50%  190.00us
+     75%  203.00us
+     90%  218.00us
+     99%  367.00us
+  12256706 requests in 5.00m, 2.96GB read
+Requests/sec:  40842.16
+Transfer/sec:     10.09MB
+----------------------------------------------------------------------
+
+--- rate-limit disabled --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   194.91us  222.55us  33.80ms   99.47%
+    Req/Sec     5.29k   167.52     5.95k    68.32%
+  Latency Distribution
+     50%  184.00us
+     75%  197.00us
+     90%  214.00us
+     99%  353.00us
+  12633928 requests in 5.00m, 3.05GB read
+Requests/sec:  42112.54
+Transfer/sec:     10.40MB
+----------------------------------------------------------------------
+
+--- rate-limit off --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   194.37us  166.76us  28.75ms   99.09%
+    Req/Sec     5.28k   160.02     5.86k    68.02%
+  Latency Distribution
+     50%  184.00us
+     75%  197.00us
+     90%  214.00us
+     99%  355.00us
+  12622896 requests in 5.00m, 3.04GB read
+Requests/sec:  42062.31
+Transfer/sec:     10.39MB
+----------------------------------------------------------------------
+

addons/otel/test/README-speed-sa

@@ -0,0 +1,144 @@
+--- rate-limit 100.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   213.08us  136.99us  17.58ms   98.10%
+    Req/Sec     4.80k   251.04     5.97k    68.01%
+  Latency Distribution
+     50%  203.00us
+     75%  223.00us
+     90%  245.00us
+     99%  405.00us
+  11464278 requests in 5.00m, 2.77GB read
+Requests/sec:  38201.61
+Transfer/sec:      9.44MB
+----------------------------------------------------------------------
+
+--- rate-limit 75.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   202.18us  121.42us  12.04ms   97.72%
+    Req/Sec     5.05k   248.48     5.85k    65.69%
+  Latency Distribution
+     50%  194.00us
+     75%  219.00us
+     90%  245.00us
+     99%  393.00us
+  12071015 requests in 5.00m, 2.91GB read
+Requests/sec:  40223.31
+Transfer/sec:      9.94MB
+----------------------------------------------------------------------
+
+--- rate-limit 50.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   190.49us  117.32us   7.33ms   97.62%
+    Req/Sec     5.37k   265.60     6.98k    65.98%
+  Latency Distribution
+     50%  181.00us
+     75%  208.00us
+     90%  237.00us
+     99%  383.00us
+  12837427 requests in 5.00m, 3.10GB read
+Requests/sec:  42777.17
+Transfer/sec:     10.57MB
+----------------------------------------------------------------------
+
+--- rate-limit 25.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   180.46us  123.40us  13.20ms   97.80%
+    Req/Sec     5.69k   242.93     7.75k    68.66%
+  Latency Distribution
+     50%  165.00us
+     75%  194.00us
+     90%  223.00us
+     99%  375.00us
+  13595213 requests in 5.00m, 3.28GB read
+Requests/sec:  45302.34
+Transfer/sec:     11.19MB
+----------------------------------------------------------------------
+
+--- rate-limit 10.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   174.69us  129.17us  16.50ms   97.93%
+    Req/Sec     5.89k   260.40     7.03k    69.57%
+  Latency Distribution
+     50%  160.00us
+     75%  178.00us
+     90%  210.00us
+     99%  374.00us
+  14068388 requests in 5.00m, 3.39GB read
+Requests/sec:  46879.07
+Transfer/sec:     11.58MB
+----------------------------------------------------------------------
+
+--- rate-limit 2.5 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   170.58us  116.89us  11.49ms   97.74%
+    Req/Sec     6.03k   249.35     6.54k    67.44%
+  Latency Distribution
+     50%  158.00us
+     75%  170.00us
+     90%  192.00us
+     99%  375.00us
+  14402604 requests in 5.00m, 3.47GB read
+Requests/sec:  47992.71
+Transfer/sec:     11.85MB
+----------------------------------------------------------------------
+
+--- rate-limit 0.0 --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   167.96us  114.36us  10.99ms   97.81%
+    Req/Sec     6.12k   266.16     6.57k    70.70%
+  Latency Distribution
+     50%  157.00us
+     75%  166.00us
+     90%  183.00us
+     99%  370.00us
+  14622790 requests in 5.00m, 3.53GB read
+Requests/sec:  48726.40
+Transfer/sec:     12.04MB
+----------------------------------------------------------------------
+
+--- rate-limit disabled --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   167.74us  114.11us  11.10ms   97.82%
+    Req/Sec     6.13k   251.71     6.57k    69.59%
+  Latency Distribution
+     50%  157.00us
+     75%  166.00us
+     90%  182.00us
+     99%  368.00us
+  14641307 requests in 5.00m, 3.53GB read
+Requests/sec:  48788.18
+Transfer/sec:     12.05MB
+----------------------------------------------------------------------
+
+--- rate-limit off --------------------------------------------------
+Running 5m test @ http://localhost:10080/index.html
+  8 threads and 8 connections
+  Thread Stats   Avg      Stdev     Max   +/- Stdev
+    Latency   168.00us  112.83us  11.07ms   97.79%
+    Req/Sec     6.12k   264.12     7.23k    68.95%
+  Latency Distribution
+     50%  157.00us
+     75%  166.00us
+     90%  183.00us
+     99%  369.00us
+  14613970 requests in 5.00m, 3.53GB read
+Requests/sec:  48697.01
+Transfer/sec:     12.03MB
+----------------------------------------------------------------------
+

addons/otel/test/README-test-speed

@@ -0,0 +1,319 @@
+                   -----------------------------------------
+                     HAProxy OTEL filter speed test guide
+                                Version 1.0
+                          ( Last update: 2026-04-09 )
+                   -----------------------------------------
+                         Author : Miroslav Zagorac
+                   Contact : mzagorac at haproxy dot com
+
+
+SUMMARY
+--------
+
+  1.    Overview
+  2.    Prerequisites
+  3.    Running the test
+  4.    Test parameters
+  5.    Rate-limit levels
+  6.    Test configurations
+  7.    Results
+  7.1.    Standalone (sa)
+  7.2.    Comparison (cmp)
+  7.3.    Context propagation (ctx)
+  7.4.    Frontend / backend (fe-be)
+  8.    Summary
+
+
+1. Overview
+------------
+
+The test-speed.sh script measures the performance impact of the OTEL filter on
+HAProxy at various rate-limit settings.  For each test configuration, the script
+iterates through a series of rate-limit values -- from full tracing (100%) down
+to the filter being completely removed -- measuring throughput and latency at
+each level.
+
+The script uses template files (haproxy.cfg.in and otel.cfg.in) from each test
+directory to generate the actual configuration files.  A sed substitution
+adjusts the rate-limit value (or disables/removes the filter) before each run.
+
+
+2. Prerequisites
+-----------------
+
+The following tools must be installed and available in PATH:
+
+  - thttpd : a lightweight HTTP server used as the backend origin server.
+             It serves a small static HTML file (index.html) on port 8000.
+
+  - wrk    : an HTTP benchmarking tool that generates the test load.
+             See https://github.com/wg/wrk
+
+
+3. Running the test
+--------------------
+
+The test is executed from the test directory.  It can be run for all
+configurations at once or for a single configuration.
+
+To run all configurations:
+
+  % ./test-speed.sh all
+
+This produces result files in the _logs directory:
+
+  _logs/README-speed-fe-be
+  _logs/README-speed-sa
+  _logs/README-speed-cmp
+  _logs/README-speed-ctx
+
+To run a single configuration:
+
+  % ./test-speed.sh <cfg> [<dir>]
+
+Where <cfg> corresponds to a run-<cfg>.sh script and <dir> is the configuration
+directory (defaults to <cfg>).  For example:
+
+  % ./test-speed.sh sa
+  % ./test-speed.sh fe-be fe
+  % ./test-speed.sh cmp
+  % ./test-speed.sh ctx
+
+
+4. Test parameters
+-------------------
+
+The wrk benchmarking tool is invoked with the following parameters:
+
+  -t8        8 threads
+  -c8        8 concurrent connections
+  -d300      5-minute test duration (300 seconds)
+  --latency  latency distribution reporting
+
+Each rate-limit level is tested sequentially.  Between runs, HAProxy is stopped
+via SIGUSR1 and restarted with the next rate-limit configuration.  A 10-second
+pause separates consecutive runs.
+
+The backend origin server (thttpd) serves a small static HTML page (index.html,
+approximately 50 bytes) on port 8000.  HAProxy listens on port 10080 and proxies
+requests to the origin.
+
+
+5. Rate-limit levels
+---------------------
+
+The script tests nine rate-limit levels in the following order:
+
+  100.0    - the filter processes every stream (worst case)
+   75.0    - the filter processes 75% of streams
+   50.0    - the filter processes 50% of streams
+   25.0    - the filter processes 25% of streams
+   10.0    - the filter processes 10% of streams
+    2.5    - the filter processes 2.5% of streams
+    0.0    - the filter is loaded and attached to every stream but never
+             processes any telemetry (the rate-limit check always fails);
+             this measures the per-stream attach and detach overhead
+
+  disabled - the filter is loaded but disabled via 'option disabled'; it is not
+             attached to streams at all; this measures the cost of loading and
+             initializing the filter library without any per-stream work
+
+  off      - the 'filter opentelemetry' and 'otel-group' directives are
+             commented out of haproxy.cfg; the filter is not loaded and has zero
+             presence in the processing path; this is the absolute baseline
+
+In the result tables, the 'overhead' column is the throughput loss relative to
+the 'off' baseline, expressed as a percentage:
+
+  overhead = (req/s_off - req/s_test) / req/s_off * 100
+
+
+6. Test configurations
+-----------------------
+
+Four OTEL filter configurations are tested.  They differ in complexity and in
+the features they exercise:
+
+  sa     - Standalone.  Uses all possible HAProxy filter events with spans,
+           attributes, events, links, baggage, status, metrics and groups.
+           This is the most comprehensive single-instance configuration and
+           represents the worst-case scenario.
+
+  cmp    - Comparison.  A simplified configuration made for comparison with
+           other tracing implementations.  It uses a reduced span hierarchy
+           without context propagation, groups or metrics.  This is closer to
+           a typical production deployment.
+
+  ctx    - Context propagation.  Similar to 'sa' in scope coverage, but spans
+           are opened using extracted span contexts (inject/extract via HAProxy
+           variables) as parent references instead of direct span names.  This
+           adds the overhead of context serialization, variable storage and
+           deserialization on every scope execution.
+
+  fe-be  - Frontend / backend.  Two cascaded HAProxy instances: the frontend
+           (fe) creates the root trace and injects span context into HTTP
+           headers; the backend (be) extracts the context and continues the
+           trace.  This configuration measures the combined overhead of two
+           OTEL filter instances plus the inter-process context propagation
+           cost.
+
+           Note: the rate-limit is varied only on the frontend.  The backend
+           always runs with its default configuration (filter enabled,
+           hard-errors on).  The backend configuration is only modified for
+           the 'disabled' and 'off' levels.
+
+
+7. Results
+-----------
+
+The tables below summarize the benchmarking results.  The 'req/s' column shows
+the sustained request rate reported by wrk, 'avg latency' is the average
+response time, and 'overhead' is the throughput loss relative to the 'off'
+baseline.
+
+
+7.1. Standalone (sa)
+---------------------
+
+  ---------------------------------------------------------------
+   rate-limit     req/s     avg latency     overhead
+  ---------------------------------------------------------------
+      100.0%     38,202       213.08 us       21.6%
+       75.0%     40,223       202.18 us       17.4%
+       50.0%     42,777       190.49 us       12.2%
+       25.0%     45,302       180.46 us        7.0%
+       10.0%     46,879       174.69 us        3.7%
+        2.5%     47,993       170.58 us        1.4%
+        0.0%     48,726       167.96 us          ~0
+     disabled    48,788       167.74 us          ~0
+     off         48,697       168.00 us      baseline
+  ---------------------------------------------------------------
+
+With all possible events active, the sa configuration at 100% rate-limit shows
+a 22% throughput reduction.  At 10% rate-limit the overhead drops to 3.7%, and
+at 2.5% it is barely measurable at 1.4%.  The 'disabled' and '0.0' levels show
+no measurable overhead above the baseline.
+
+
+7.2. Comparison (cmp)
+----------------------
+
+  ---------------------------------------------------------------
+   rate-limit     req/s     avg latency     overhead
+  ---------------------------------------------------------------
+      100.0%     44,780       182.58 us        7.6%
+       75.0%     45,362       180.10 us        6.4%
+       50.0%     46,279       176.59 us        4.6%
+       25.0%     47,061       173.57 us        2.9%
+       10.0%     47,793       170.85 us        1.4%
+        2.5%     48,410       169.11 us        0.2%
+        0.0%     48,586       168.09 us          ~0
+     disabled    48,510       168.57 us          ~0
+     off         48,488       168.64 us      baseline
+  ---------------------------------------------------------------
+
+The simplified cmp configuration shows significantly lower overhead than sa at
+every rate-limit level.  At 100% rate-limit the overhead is 7.6%, at 10% it is
+1.4%, and below 2.5% it becomes indistinguishable from the baseline.
+
+
+7.3. Context propagation (ctx)
+-------------------------------
+
+  ---------------------------------------------------------------
+   rate-limit     req/s     avg latency     overhead
+  ---------------------------------------------------------------
+      100.0%     30,032       270.35 us       38.0%
+       75.0%     33,490       242.56 us       30.9%
+       50.0%     37,679       215.92 us       22.2%
+       25.0%     42,449       192.36 us       12.4%
+       10.0%     45,458       180.08 us        6.2%
+        2.5%     47,546       171.64 us        1.9%
+        0.0%     48,313       168.86 us        0.3%
+     disabled    48,620       168.36 us          ~0
+     off         48,446       168.73 us      baseline
+  ---------------------------------------------------------------
+
+The ctx configuration is the most expensive due to the inject/extract cycle on
+every scope execution.  At 100% rate-limit the overhead reaches 38%.  However,
+the cost scales linearly with the rate-limit: at 10% the overhead is 6.2%, and
+at 2.5% it drops to 1.9%.  The filter attachment overhead (0.0% vs off) is
+negligible at 0.3%.
+
+
+7.4. Frontend / backend (fe-be)
+--------------------------------
+
+  ---------------------------------------------------------------
+   rate-limit     req/s     avg latency     overhead
+  ---------------------------------------------------------------
+      100.0%     34,012       238.75 us       19.1%
+       75.0%     35,462       230.08 us       15.7%
+       50.0%     36,811       222.33 us       12.5%
+       25.0%     38,493       210.95 us        8.5%
+       10.0%     39,735       206.15 us        5.5%
+        2.5%     40,423       202.35 us        3.9%
+        0.0%     40,842       200.88 us        2.9%
+     disabled    42,113       194.91 us          ~0
+     off         42,062       194.37 us      baseline
+  ---------------------------------------------------------------
+
+The fe-be configuration involves two HAProxy instances in series, so the
+absolute baseline (off) is already lower at 42,062 req/s due to the extra
+network hop.  The rate-limit is varied only on the frontend; the backend
+always has the filter loaded with hard-errors enabled.
+
+This explains the 2.9% overhead at rate-limit 0.0: even though the frontend
+never traces, the backend filter still attaches to every stream, attempts to
+extract context from the HTTP headers, fails (because the frontend did not
+inject any context), and the hard-errors option stops further processing.
+This per-stream attach/extract/error cycle accounts for the residual cost.
+
+When both instances have the filter disabled (disabled level), the overhead
+is within measurement noise, consistent with the single-instance
+configurations.
+
+
+8. Summary
+-----------
+
+The table below shows the overhead for each configuration at selected rate-limit
+levels:
+
+  ---------------------------------------------------
+   rate-limit    sa      cmp      ctx     fe-be
+  ---------------------------------------------------
+      100.0%   21.6%    7.6%    38.0%    19.1%
+       25.0%    7.0%    2.9%    12.4%     8.5%
+       10.0%    3.7%    1.4%     6.2%     5.5%
+        2.5%    1.4%    0.2%     1.9%     3.9%
+  ---------------------------------------------------
+
+Key observations:
+
+  - The overhead scales approximately linearly with the rate-limit value.
+    Reducing the rate-limit from 100% to 10% eliminates the vast majority
+    of the cost in all configurations.
+
+  - The cmp configuration, which uses a reduced span hierarchy typical of
+    production deployments, adds only 1.4% overhead at a 10% rate-limit.
+
+  - The sa configuration, which exercises all possible events, stays at about
+    7% overhead at a 25% rate-limit and below 4% at 10%.
+
+  - The ctx configuration is the most expensive due to the inject/extract
+    context propagation on every scope.  It is designed as a stress test for
+    the propagation mechanism rather than a practical production template.
+
+  - The fe-be configuration carries a higher fixed cost because two HAProxy
+    instances are involved and the backend filter processes context extraction
+    regardless of the frontend rate-limit setting.
+
+  - Loading the filter but disabling it via 'option disabled' adds no measurable
+    overhead in any configuration.
+
+  - The filter attachment cost without any telemetry processing (rate-limit 0.0)
+    is 0.3% or less for single-instance configurations (sa, cmp, ctx).
+
+  - In typical production use with a rate-limit of 10% or less, the performance
+    impact of the OTEL filter should be negligible for single-instance deployments.

addons/otel/test/be/haproxy.cfg

@@ -0,0 +1,19 @@
+global
+    stats socket /tmp/haproxy-be.sock mode 666 level admin
+
+listen stats
+    mode http
+    bind *:8002
+    stats uri /
+    stats admin if TRUE
+    stats refresh 10s
+
+frontend otel-test-be-frontend
+    bind *:11080
+    default_backend servers-backend
+
+    # OTel filter
+    filter opentelemetry id otel-test-be config be/otel.cfg
+
+backend servers-backend
+    server server-1 127.0.0.1:8000

addons/otel/test/be/otel.cfg

@@ -0,0 +1,61 @@
+[otel-test-be]
+    otel-instrumentation otel-test-instrumentation
+        config be/otel.yml
+#       log localhost:514 local7 debug
+        option dontlog-normal
+        option hard-errors
+        no option disabled
+
+        scopes frontend_http_request
+        scopes backend_tcp_request
+        scopes backend_http_request
+        scopes client_session_end
+
+        scopes server_session_start
+        scopes tcp_response
+        scopes http_response
+        scopes server_session_end
+
+    otel-scope frontend_http_request
+        extract "otel-ctx" use-headers
+        span "HAProxy session" parent "otel-ctx" root
+            baggage "haproxy_id" var(sess.otel.uuid)
+        span "Client session" parent "HAProxy session"
+        span "Frontend HTTP request" parent "Client session"
+            attribute "http.method" method
+            attribute "http.url" url
+            attribute "http.version" str("HTTP/") req.ver
+        otel-event on-frontend-http-request
+
+    otel-scope backend_tcp_request
+        span "Backend TCP request" parent "Frontend HTTP request"
+        finish "Frontend HTTP request"
+        otel-event on-backend-tcp-request
+
+    otel-scope backend_http_request
+        span "Backend HTTP request" parent "Backend TCP request"
+        finish "Backend TCP request"
+        otel-event on-backend-http-request
+
+    otel-scope client_session_end
+        finish "Client session"
+        otel-event on-client-session-end
+
+    otel-scope server_session_start
+        span "Server session" parent "HAProxy session"
+        finish "Backend HTTP request"
+        otel-event on-server-session-start
+
+    otel-scope tcp_response
+        span "TCP response" parent "Server session"
+        otel-event on-tcp-response
+
+    otel-scope http_response
+        span "HTTP response" parent "TCP response"
+            attribute "http.status_code" status
+        finish "TCP response"
+        otel-event on-http-response
+
+    otel-scope server_session_end
+        finish *
+        otel-event on-server-session-end

addons/otel/test/be/otel.yml

@@ -0,0 +1,246 @@
+exporters:
+  exporter_traces_otlp_file:
+    type:           otlp_file
+    thread_name:    "OTLP/file trace"
+    file_pattern:   "__be_traces_log-%F-%N"
+    alias_pattern:  "__traces_log-latest"
+    flush_interval: 30000000
+    flush_count:    256
+    file_size:      134217728
+    rotate_size:    5
+
+  exporter_traces_otlp_grpc:
+    type:                             otlp_grpc
+    thread_name:                      "OTLP/gRPC trace"
+    endpoint:                         "http://localhost:4317/v1/traces"
+    use_ssl_credentials:              false
+#   ssl_credentials_cacert_path:      ""
+#   ssl_credentials_cacert_as_string: ""
+#   ssl_client_key_path:              ""
+#   ssl_client_key_string:            ""
+#   ssl_client_cert_path:             ""
+#   ssl_client_cert_string:           ""
+#   timeout:                          10
+#   user_agent:                       ""
+#   max_threads:                      0
+#   compression:                      ""
+#   max_concurrent_requests:          0
+
+  exporter_traces_otlp_http:
+    type:                        otlp_http
+    thread_name:                 "OTLP/HTTP trace"
+    endpoint:                    "http://localhost:4318/v1/traces"
+    content_type:                json
+    json_bytes_mapping:          hexid
+    debug:                       false
+    timeout:                     10
+    http_headers:
+      - X-OTel-Header-1:         "OTLP HTTP traces test header #1"
+      - X-OTel-Header-2:         "OTLP HTTP traces test header #2"
+    max_concurrent_requests:     64
+    max_requests_per_connection: 8
+    ssl_insecure_skip_verify:    true
+#   ssl_ca_cert_path:            ""
+#   ssl_ca_cert_string:          ""
+#   ssl_client_key_path:         ""
+#   ssl_client_key_string:       ""
+#   ssl_client_cert_path:        ""
+#   ssl_client_cert_string:      ""
+#   ssl_min_tls:                 ""
+#   ssl_max_tls:                 ""
+#   ssl_cipher:                  ""
+#   ssl_cipher_suite:            ""
+#   compression:                 ""
+
+  exporter_traces_dev_null:
+    type:     ostream
+    filename: /dev/null
+
+  exporter_traces_ostream:
+    type:     ostream
+    filename: __be_traces
+
+  exporter_traces_memory:
+    type:        memory
+    buffer_size: 256
+
+  exporter_traces_zipkin:
+    type:           zipkin
+    endpoint:       "http://localhost:9411/api/v2/spans"
+    format:         json
+    service_name:   "zipkin-service"
+#   ipv4:           ""
+#   ipv6:           ""
+
+  exporter_metrics_otlp_file:
+    type:           otlp_file
+    thread_name:    "OTLP/file metr"
+    file_pattern:   "__be_metrics_log-%F-%N"
+    alias_pattern:  "__metrics_log-latest"
+    flush_interval: 30000000
+    flush_count:    256
+    file_size:      134217728
+    rotate_size:    5
+
+  exporter_metrics_otlp_grpc:
+    type:                otlp_grpc
+    thread_name:         "OTLP/gRPC metr"
+    endpoint:            "http://localhost:4317/v1/metrics"
+    use_ssl_credentials: false
+
+  exporter_metrics_otlp_http:
+    type:                        otlp_http
+    thread_name:                 "OTLP/HTTP metr"
+    endpoint:                    "http://localhost:4318/v1/metrics"
+    content_type:                json
+    debug:                       false
+    timeout:                     10
+    http_headers:
+      - X-OTel-Header-1:         "OTLP HTTP metrics test header #1"
+      - X-OTel-Header-2:         "OTLP HTTP metrics test header #2"
+    max_concurrent_requests:     64
+    max_requests_per_connection: 8
+    ssl_insecure_skip_verify:    true
+
+  exporter_metrics_dev_null:
+    type:     ostream
+    filename: /dev/null
+
+  exporter_metrics_ostream:
+    type:     ostream
+    filename: __be_metrics
+
+  exporter_metrics_memory:
+    type:        memory
+    buffer_size: 256
+
+  exporter_logs_otlp_file:
+    type:           otlp_file
+    thread_name:    "OTLP/file logs"
+    file_pattern:   "__be_logs_log-%F-%N"
+    alias_pattern:  "__logs_log-latest"
+    flush_interval: 30000000
+    flush_count:    256
+    file_size:      134217728
+    rotate_size:    5
+
+  exporter_logs_otlp_grpc:
+    type:                otlp_grpc
+    thread_name:         "OTLP/gRPC logs"
+    endpoint:            "http://localhost:4317/v1/logs"
+    use_ssl_credentials: false
+
+  exporter_logs_otlp_http:
+    type:                        otlp_http
+    thread_name:                 "OTLP/HTTP logs"
+    endpoint:                    "http://localhost:4318/v1/logs"
+    content_type:                json
+    debug:                       false
+    timeout:                     10
+    http_headers:
+      - X-OTel-Header-1:         "OTLP HTTP logs test header #1"
+      - X-OTel-Header-2:         "OTLP HTTP logs test header #2"
+    max_concurrent_requests:     64
+    max_requests_per_connection: 8
+    ssl_insecure_skip_verify:    true
+
+  exporter_logs_dev_null:
+    type:     ostream
+    filename: /dev/null
+
+  exporter_logs_ostream:
+    type:     ostream
+    filename: __be_logs
+
+  exporter_logs_elasticsearch:
+    type:             elasticsearch
+    host:             localhost
+    port:             9200
+    index:            logs
+    response_timeout: 30
+    debug:            false
+    http_headers:
+      - X-OTel-Header-1: "Elasticsearch logs test header #1"
+      - X-OTel-Header-2: "Elasticsearch logs test header #2"
+
+readers:
+  reader_metrics:
+    thread_name:     "reader metr"
+    export_interval: 10000
+    export_timeout:  5000
+
+samplers:
+  sampler_traces:
+#   type:  always_on
+#   type:  always_off
+#   type:  trace_id_ratio_based
+#   ratio: 1.0
+    type:     parent_based
+    delegate: always_on
+
+processors:
+  processor_traces_batch:
+    type:                  batch
+    thread_name:           "proc/batch trac"
+    # Note: when the queue is half full, a preemptive notification is sent
+    # to start the export call.
+    max_queue_size:        2048
+    # Time interval (in ms) between two consecutive exports
+    schedule_delay:        5000
+    # Export 'max_export_batch_size' after every `schedule_delay' milliseconds.
+    max_export_batch_size: 512
+
+  processor_traces_single:
+    type:                  single
+
+  processor_logs_batch:
+    type:                  batch
+    thread_name:           "proc/batch logs"
+    max_queue_size:        2048
+    schedule_delay:        5000
+    max_export_batch_size: 512
+
+  processor_logs_single:
+    type:                  single
+
+providers:
+  provider_traces:
+    resources:
+      - service.version:     "1.0.0"
+      - service.instance.id: "id-be"
+      - service.name:        "be"
+      - service.namespace:   "HAProxy traces test"
+
+  provider_metrics:
+    resources:
+      - service.version:     "1.0.0"
+      - service.instance.id: "id-be"
+      - service.name:        "be"
+      - service.namespace:   "HAProxy metrics test"
+
+  provider_logs:
+    resources:
+      - service.version:     "1.0.0"
+      - service.instance.id: "id-be"
+      - service.name:        "be"
+      - service.namespace:   "HAProxy logs test"
+
+signals:
+  traces:
+    scope_name: "HAProxy OTEL - traces"
+    exporters:  exporter_traces_otlp_http
+    samplers:   sampler_traces
+    processors: processor_traces_batch
+    providers:  provider_traces
+
+  metrics:
+    scope_name: "HAProxy OTEL - metrics"
+    exporters:  exporter_metrics_otlp_http
+    readers:    reader_metrics
+    providers:  provider_metrics
+
+  logs:
+    scope_name: "HAProxy OTEL - logs"
+    exporters:  exporter_logs_otlp_http
+    processors: processor_logs_batch
+    providers:  provider_logs

addons/otel/test/cmp/haproxy.cfg

@@ -0,0 +1,22 @@
+global
+    stats socket /tmp/haproxy.sock mode 666 level admin
+
+listen stats
+    mode http
+    bind *:8001
+    stats uri /
+    stats admin if TRUE
+    stats refresh 10s
+
+frontend otel-test-cmp-frontend
+    bind *:10080
+    default_backend servers-backend
+
+    # ACL used to distinguish successful from error responses
+    acl acl-http-status-ok status 100:399
+
+    # OTel filter
+    filter opentelemetry id otel-test-cmp config cmp/otel.cfg
+
+backend servers-backend
+    server server-1 127.0.0.1:8000

addons/otel/test/cmp/otel.cfg

@@ -0,0 +1,81 @@
+[otel-test-cmp]
+    otel-instrumentation otel-test-instrumentation
+        config cmp/otel.yml
+#       log localhost:514 local7 debug
+        option dontlog-normal
+        option hard-errors
+        no option disabled
+        rate-limit 100.0
+
+        scopes client_session_start
+        scopes frontend_tcp_request
+        scopes frontend_http_request
+        scopes backend_tcp_request
+        scopes backend_http_request
+        scopes server_unavailable
+
+        scopes server_session_start
+        scopes tcp_response
+        scopes http_response http_response-error server_session_end client_session_end
+
+    otel-scope client_session_start
+        span "HAProxy session" root
+            baggage "haproxy_id" var(sess.otel.uuid)
+        span "Client session" parent "HAProxy session"
+        otel-event on-client-session-start
+
+    otel-scope frontend_tcp_request
+        span "Frontend TCP request" parent "Client session"
+        otel-event on-frontend-tcp-request
+
+    otel-scope frontend_http_request
+        span "Frontend HTTP request" parent "Frontend TCP request"
+            attribute "http.method" method
+            attribute "http.url" url
+            attribute "http.version" str("HTTP/") req.ver
+        finish "Frontend TCP request"
+        otel-event on-frontend-http-request
+
+    otel-scope backend_tcp_request
+        span "Backend TCP request" parent "Frontend HTTP request"
+        finish "Frontend HTTP request"
+        otel-event on-backend-tcp-request
+
+    otel-scope backend_http_request
+        span "Backend HTTP request" parent "Backend TCP request"
+        finish "Backend TCP request"
+        otel-event on-backend-http-request
+
+    otel-scope server_unavailable
+        span "HAProxy session"
+            status "error" str("503 Service Unavailable")
+        finish *
+        otel-event on-server-unavailable
+
+    otel-scope server_session_start
+        span "Server session" parent "HAProxy session"
+        finish "Backend HTTP request"
+        otel-event on-server-session-start
+
+    otel-scope tcp_response
+        span "TCP response" parent "Server session"
+        otel-event on-tcp-response
+
+    otel-scope http_response
+        span "HTTP response" parent "TCP response"
+            attribute "http.status_code" status
+        finish "TCP response"
+        otel-event on-http-response
+
+    otel-scope http_response-error
+        span "HTTP response"
+            status "error" str("!acl-http-status-ok")
+        otel-event on-http-response if !acl-http-status-ok
+
+    otel-scope server_session_end
+        finish "HTTP response" "Server session"
+        otel-event on-http-response
+
+    otel-scope client_session_end
+        finish "*"
+        otel-event on-http-response

addons/otel/test/cmp/otel.yml

@@ -0,0 +1,246 @@
+exporters:
+  exporter_traces_otlp_file:
+    type:           otlp_file
+    thread_name:    "OTLP/file trace"
+    file_pattern:   "__cmp_traces_log-%F-%N"
+    alias_pattern:  "__traces_log-latest"
+    flush_interval: 30000000
+    flush_count:    256
+    file_size:      134217728
+    rotate_size:    5
+
+  exporter_traces_otlp_grpc:
+    type:                             otlp_grpc
+    thread_name:                      "OTLP/gRPC trace"
+    endpoint:                         "http://localhost:4317/v1/traces"
+    use_ssl_credentials:              false
+#   ssl_credentials_cacert_path:      ""
+#   ssl_credentials_cacert_as_string: ""
+#   ssl_client_key_path:              ""
+#   ssl_client_key_string:            ""
+#   ssl_client_cert_path:             ""
+#   ssl_client_cert_string:           ""
+#   timeout:                          10
+#   user_agent:                       ""
+#   max_threads:                      0
+#   compression:                      ""
+#   max_concurrent_requests:          0
+
+  exporter_traces_otlp_http:
+    type:                        otlp_http
+    thread_name:                 "OTLP/HTTP trace"
+    endpoint:                    "http://localhost:4318/v1/traces"
+    content_type:                json
+    json_bytes_mapping:          hexid
+    debug:                       false
+    timeout:                     10
+    http_headers:
+      - X-OTel-Header-1:         "OTLP HTTP traces test header #1"
+      - X-OTel-Header-2:         "OTLP HTTP traces test header #2"
+    max_concurrent_requests:     64
+    max_requests_per_connection: 8
+    ssl_insecure_skip_verify:    true
+#   ssl_ca_cert_path:            ""
+#   ssl_ca_cert_string:          ""
+#   ssl_client_key_path:         ""
+#   ssl_client_key_string:       ""
+#   ssl_client_cert_path:        ""
+#   ssl_client_cert_string:      ""
+#   ssl_min_tls:                 ""
+#   ssl_max_tls:                 ""
+#   ssl_cipher:                  ""
+#   ssl_cipher_suite:            ""
+#   compression:                 ""
+
+  exporter_traces_dev_null:
+    type:     ostream
+    filename: /dev/null
+
+  exporter_traces_ostream:
+    type:     ostream
+    filename: __cmp_traces
+
+  exporter_traces_memory:
+    type:        memory
+    buffer_size: 256
+
+  exporter_traces_zipkin:
+    type:           zipkin
+    endpoint:       "http://localhost:9411/api/v2/spans"
+    format:         json
+    service_name:   "zipkin-service"
+#   ipv4:           ""
+#   ipv6:           ""
+
+  exporter_metrics_otlp_file:
+    type:           otlp_file
+    thread_name:    "OTLP/file metr"
+    file_pattern:   "__cmp_metrics_log-%F-%N"
+    alias_pattern:  "__metrics_log-latest"
+    flush_interval: 30000000
+    flush_count:    256
+    file_size:      134217728
+    rotate_size:    5
+
+  exporter_metrics_otlp_grpc:
+    type:                otlp_grpc
+    thread_name:         "OTLP/gRPC metr"
+    endpoint:            "http://localhost:4317/v1/metrics"
+    use_ssl_credentials: false
+
+  exporter_metrics_otlp_http:
+    type:                        otlp_http
+    thread_name:                 "OTLP/HTTP metr"
+    endpoint:                    "http://localhost:4318/v1/metrics"
+    content_type:                json
+    debug:                       false
+    timeout:                     10
+    http_headers:
+      - X-OTel-Header-1:         "OTLP HTTP metrics test header #1"
+      - X-OTel-Header-2:         "OTLP HTTP metrics test header #2"
+    max_concurrent_requests:     64
+    max_requests_per_connection: 8
+    ssl_insecure_skip_verify:    true
+
+  exporter_metrics_dev_null:
+    type:     ostream
+    filename: /dev/null
+
+  exporter_metrics_ostream:
+    type:     ostream
+    filename: __cmp_metrics
+
+  exporter_metrics_memory:
+    type:        memory
+    buffer_size: 256
+
+  exporter_logs_otlp_file:
+    type:           otlp_file
+    thread_name:    "OTLP/file logs"
+    file_pattern:   "__cmp_logs_log-%F-%N"
+    alias_pattern:  "__logs_log-latest"
+    flush_interval: 30000000
+    flush_count:    256
+    file_size:      134217728
+    rotate_size:    5
+
+  exporter_logs_otlp_grpc:
+    type:                otlp_grpc
+    thread_name:         "OTLP/gRPC logs"
+    endpoint:            "http://localhost:4317/v1/logs"
+    use_ssl_credentials: false
+
+  exporter_logs_otlp_http:
+    type:                        otlp_http
+    thread_name:                 "OTLP/HTTP logs"
+    endpoint:                    "http://localhost:4318/v1/logs"
+    content_type:                json
+    debug:                       false
+    timeout:                     10
+    http_headers:
+      - X-OTel-Header-1:         "OTLP HTTP logs test header #1"
+      - X-OTel-Header-2:         "OTLP HTTP logs test header #2"
+    max_concurrent_requests:     64
+    max_requests_per_connection: 8
+    ssl_insecure_skip_verify:    true
+
+  exporter_logs_dev_null:
+    type:     ostream
+    filename: /dev/null
+
+  exporter_logs_ostream:
+    type:     ostream
+    filename: __cmp_logs
+
+  exporter_logs_elasticsearch:
+    type:             elasticsearch
+    host:             localhost
+    port:             9200
+    index:            logs
+    response_timeout: 30
+    debug:            false
+    http_headers:
+      - X-OTel-Header-1: "Elasticsearch logs test header #1"
+      - X-OTel-Header-2: "Elasticsearch logs test header #2"
+
+readers:
+  reader_metrics:
+    thread_name:     "reader metr"
+    export_interval: 10000
+    export_timeout:  5000
+
+samplers:
+  sampler_traces:
+#   type:  always_on
+#   type:  always_off
+#   type:  trace_id_ratio_based
+#   ratio: 1.0
+    type:     parent_based
+    delegate: always_on
+
+processors:
+  processor_traces_batch:
+    type:                  batch
+    thread_name:           "proc/batch trac"
+    # Note: when the queue is half full, a preemptive notification is sent
+    # to start the export call.
+    max_queue_size:        2048
+    # Time interval (in ms) between two consecutive exports
+    schedule_delay:        5000
+    # Export 'max_export_batch_size' after every `schedule_delay' milliseconds.
+    max_export_batch_size: 512
+
+  processor_traces_single:
+    type:                  single
+
+  processor_logs_batch:
+    type:                  batch
+    thread_name:           "proc/batch logs"
+    max_queue_size:        2048
+    schedule_delay:        5000
+    max_export_batch_size: 512
+
+  processor_logs_single:
+    type:                  single
+
+providers:
+  provider_traces:
+    resources:
+      - service.version:     "1.0.0"
+      - service.instance.id: "id-cmp"
+      - service.name:        "cmp"
+      - service.namespace:   "HAProxy traces test"
+
+  provider_metrics:
+    resources:
+      - service.version:     "1.0.0"
+      - service.instance.id: "id-cmp"
+      - service.name:        "cmp"
+      - service.namespace:   "HAProxy metrics test"
+
+  provider_logs:
+    resources:
+      - service.version:     "1.0.0"
+      - service.instance.id: "id-cmp"
+      - service.name:        "cmp"
+      - service.namespace:   "HAProxy logs test"
+
+signals:
+  traces:
+    scope_name: "HAProxy OTEL - traces"
+    exporters:  exporter_traces_otlp_http
+    samplers:   sampler_traces
+    processors: processor_traces_batch
+    providers:  provider_traces
+
+  metrics:
+    scope_name: "HAProxy OTEL - metrics"
+    exporters:  exporter_metrics_otlp_http
+    readers:    reader_metrics
+    providers:  provider_metrics
+
+  logs:
+    scope_name: "HAProxy OTEL - logs"
+    exporters:  exporter_logs_otlp_http
+    processors: processor_logs_batch
+    providers:  provider_logs

addons/otel/test/copy-yml.sh

@@ -0,0 +1,24 @@
+#!/bin/sh -u
+#
+# Copyright 2026 HAProxy Technologies, Miroslav Zagorac <mzagorac@haproxy.com>
+#
+SH_FILE="${1:-}"
+ SH_EXT="${2:-}"
+
+
+if test ${#} -ne 2; then
+	echo
+	echo "usage: $(basename "${0}") input-file test-name"
+	echo
+	exit 64
+fi
+
+sed '
+	s/^\( *\)\(filename:\)\( *\)_\(_[a-z]*\)/\1\2\3__'"${SH_EXT}"'\4/g
+	s/^\( *\)\(file_pattern:\)\( *\)"_\(_[a-z]*_[^"]*\)"/\1\2\3"__'"${SH_EXT}"'\4"/g
+	s/^\( *\)\(- service.instance.id:\)\( *\).*/\1\2\3"id-'"${SH_EXT}"'"/g
+	s/^\( *\)\(- service.name:\)\( *\).*/\1\2\3"'"${SH_EXT}"'"/g
+	s/^\( *\)\(- service.namespace:\)\( *\)\("otelc\)/\1\2\3"HAProxy/g
+	s/^\( *\)\(scope_name:\)\( *\)"OTEL C wrapper /\1\2 "HAProxy OTEL /g
+	s/^\( *\)\(exporters:\)\( *\)\(exporter_[a-z]*_\).*/\1\2\3\4otlp_http/g
+' "${SH_FILE}"

addons/otel/test/ctx/haproxy.cfg

@@ -0,0 +1,28 @@
+global
+    stats socket /tmp/haproxy.sock mode 666 level admin
+
+listen stats
+    mode http
+    bind *:8001
+    stats uri /
+    stats admin if TRUE
+    stats refresh 10s
+
+frontend otel-test-ctx-frontend
+    bind *:10080
+    default_backend servers-backend
+
+    # ACL used to distinguish successful from error responses
+    acl acl-http-status-ok status 100:399
+
+    # OTel filter
+    filter opentelemetry id otel-test-ctx config ctx/otel.cfg
+
+    # run response scopes for successful responses
+    http-response otel-group otel-test-ctx http_response_group if acl-http-status-ok
+
+    # run after-response scopes for error responses
+    http-after-response otel-group otel-test-ctx http_after_response_group if !acl-http-status-ok
+
+backend servers-backend
+    server server-1 127.0.0.1:8000

addons/otel/test/ctx/otel.cfg

@@ -0,0 +1,196 @@
+[otel-test-ctx]
+    otel-instrumentation otel-test-instrumentation
+        debug-level 0x77f
+        log localhost:514 local7 debug
+        config ctx/otel.yml
+        option dontlog-normal
+        option hard-errors
+        no option disabled
+        rate-limit 100.0
+
+        groups http_response_group
+        groups http_after_response_group
+
+        scopes client_session_start_1
+        scopes client_session_start_2
+        scopes frontend_tcp_request
+        scopes http_wait_request
+        scopes http_body_request
+        scopes frontend_http_request
+        scopes switching_rules_request
+        scopes backend_tcp_request
+        scopes backend_http_request
+        scopes process_server_rules_request
+        scopes http_process_request
+        scopes tcp_rdp_cookie_request
+        scopes process_sticking_rules_request
+        scopes client_session_end
+        scopes server_unavailable
+
+        scopes server_session_start
+        scopes tcp_response
+        scopes http_wait_response
+        scopes process_store_rules_response
+        scopes http_response http_response-error
+        scopes server_session_end
+
+    otel-group http_response_group
+        scopes http_response_1
+        scopes http_response_2
+
+    otel-scope http_response_1
+        span "HTTP response"
+            event "event_1" "hdr.content" res.hdr("content-type") str("; length: ") res.hdr("content-length") str(" bytes")
+
+    otel-scope http_response_2
+        span "HTTP response"
+            event "event_2" "hdr.date" res.hdr("date") str(" / ") res.hdr("last-modified")
+
+    otel-group http_after_response_group
+        scopes http_after_response
+
+    otel-scope http_after_response
+        span "HAProxy response" parent "HAProxy session"
+            status "error" str("http.status_code") status
+
+    otel-scope client_session_start_1
+        span "HAProxy session" root
+            inject "otel_ctx_1" use-headers use-vars
+            baggage "haproxy_id" var(sess.otel.uuid)
+        otel-event on-client-session-start
+
+    otel-scope client_session_start_2
+        extract "otel_ctx_1" use-vars
+        span "Client session" parent "otel_ctx_1"
+            inject "otel_ctx_2" use-headers use-vars
+        otel-event on-client-session-start
+
+    otel-scope frontend_tcp_request
+        extract "otel_ctx_2" use-vars
+        span "Frontend TCP request" parent "otel_ctx_2"
+            inject "otel_ctx_3" use-headers use-vars
+        otel-event on-frontend-tcp-request
+
+    otel-scope http_wait_request
+        extract "otel_ctx_3" use-vars
+        span "HTTP wait request" parent "otel_ctx_3"
+            inject "otel_ctx_4" use-headers use-vars
+        finish "Frontend TCP request" "otel_ctx_3"
+        otel-event on-http-wait-request
+
+    otel-scope http_body_request
+        extract "otel_ctx_4" use-vars
+        span "HTTP body request" parent "otel_ctx_4"
+            inject "otel_ctx_5" use-headers use-vars
+        finish "HTTP wait request" "otel_ctx_4"
+        otel-event on-http-body-request
+
+    otel-scope frontend_http_request
+        extract "otel_ctx_5" use-vars
+        span "Frontend HTTP request" parent "otel_ctx_5"
+            attribute "http.method" method
+            attribute "http.url" url
+            attribute "http.version" str("HTTP/") req.ver
+            inject "otel_ctx_6" use-headers use-vars
+        finish "HTTP body request" "otel_ctx_5"
+        otel-event on-frontend-http-request
+
+    otel-scope switching_rules_request
+        extract "otel_ctx_6" use-vars
+        span "Switching rules request" parent "otel_ctx_6"
+            inject "otel_ctx_7" use-headers use-vars
+        finish "Frontend HTTP request" "otel_ctx_6"
+        otel-event on-switching-rules-request
+
+    otel-scope backend_tcp_request
+        extract "otel_ctx_7" use-vars
+        span "Backend TCP request" parent "otel_ctx_7"
+            inject "otel_ctx_8" use-headers use-vars
+        finish "Switching rules request" "otel_ctx_7"
+        otel-event on-backend-tcp-request
+
+    otel-scope backend_http_request
+        extract "otel_ctx_8" use-vars
+        span "Backend HTTP request" parent "otel_ctx_8"
+            inject "otel_ctx_9" use-headers use-vars
+        finish "Backend TCP request" "otel_ctx_8"
+        otel-event on-backend-http-request
+
+    otel-scope process_server_rules_request
+        extract "otel_ctx_9" use-vars
+        span "Process server rules request" parent "otel_ctx_9"
+            inject "otel_ctx_10" use-headers use-vars
+        finish "Backend HTTP request" "otel_ctx_9"
+        otel-event on-process-server-rules-request
+
+    otel-scope http_process_request
+        extract "otel_ctx_10" use-vars
+        span "HTTP process request" parent "otel_ctx_10"
+            inject "otel_ctx_11" use-headers use-vars
+        finish "Process server rules request" "otel_ctx_10"
+        otel-event on-http-process-request
+
+    otel-scope tcp_rdp_cookie_request
+        extract "otel_ctx_11" use-vars
+        span "TCP RDP cookie request" parent "otel_ctx_11"
+            inject "otel_ctx_12" use-headers use-vars
+        finish "HTTP process request" "otel_ctx_11"
+        otel-event on-tcp-rdp-cookie-request
+
+    otel-scope process_sticking_rules_request
+        extract "otel_ctx_12" use-vars
+        span "Process sticking rules request" parent "otel_ctx_12"
+            inject "otel_ctx_13" use-headers use-vars
+        finish "TCP RDP cookie request" "otel_ctx_12"
+        otel-event on-process-sticking-rules-request
+
+    otel-scope client_session_end
+        finish "Client session" "otel_ctx_2"
+        otel-event on-client-session-end
+
+    otel-scope server_unavailable
+        finish *
+        otel-event on-server-unavailable
+
+    otel-scope server_session_start
+        span "Server session" parent "otel_ctx_1"
+            inject "otel_ctx_14" use-vars
+        extract "otel_ctx_13" use-vars
+        finish "Process sticking rules request" "otel_ctx_13"
+        otel-event on-server-session-start
+
+    otel-scope tcp_response
+        extract "otel_ctx_14" use-vars
+        span "TCP response" parent "otel_ctx_14"
+            inject "otel_ctx_15" use-vars
+        otel-event on-tcp-response
+
+    otel-scope http_wait_response
+        extract "otel_ctx_15" use-vars
+        span "HTTP wait response" parent "otel_ctx_15"
+            inject "otel_ctx_16" use-headers use-vars
+        finish "TCP response" "otel_ctx_15"
+        otel-event on-http-wait-response
+
+    otel-scope process_store_rules_response
+        extract "otel_ctx_16" use-vars
+        span "Process store rules response" parent "otel_ctx_16"
+            inject "otel_ctx_17" use-headers use-vars
+        finish "HTTP wait response" "otel_ctx_16"
+        otel-event on-process-store-rules-response
+
+    otel-scope http_response
+        extract "otel_ctx_17" use-vars
+        span "HTTP response" parent "otel_ctx_17"
+            attribute "http.status_code" status
+        finish "Process store rules response" "otel_ctx_17"
+        otel-event on-http-response
+
+    otel-scope http_response-error
+        span "HTTP response"
+            status "error" str("!acl-http-status-ok")
+        otel-event on-http-response if !acl-http-status-ok
+
+    otel-scope server_session_end
+        finish *
+        otel-event on-server-session-end