HAProxy - Load balancer
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Miroslav Zagorac cd14abf9f3 MEDIUM: otel: added OpenTelemetry filter skeleton
The OpenTelemetry (OTel) filter enables distributed tracing of requests
across service boundaries, export of metrics such as request rates,
latencies and error counts, and structured logging tied to trace context,
giving operators a unified view of HAProxy traffic through any
OpenTelemetry-compatible backend.

The OTel filter is implemented using the standard HAProxy stream filter
API.  Stream filters attach to proxies and intercept traffic at each stage
of processing: they receive callbacks on stream creation and destruction,
channel analyzer events, HTTP header and payload processing, and TCP data
forwarding.  This allows the filter to collect telemetry data at every
stage of the request/response lifecycle without modifying the core proxy
logic.

This commit added the minimum set of files required for the filter to
compile: the addon Makefile with pkg-config-based detection of the
opentelemetry-c-wrapper library, header files with configuration
constants, utility macros and type definitions, and the source files
containing stub filter operation callbacks registered through
flt_otel_ops and the "opentelemetry" keyword parser entry point.

The filter uses the opentelemetry-c-wrapper library from HAProxy
Technologies, which provides a C interface to the OpenTelemetry C++ SDK.
This wrapper allows HAProxy, a C codebase, to leverage the full
OpenTelemetry observability pipeline without direct C++ dependencies
in the HAProxy source tree.

  https://github.com/haproxytech/opentelemetry-c-wrapper
  https://github.com/open-telemetry/opentelemetry-cpp

Build options:

  USE_OTEL     - enable the OpenTelemetry filter
  OTEL_DEBUG   - compile the filter in debug mode
  OTEL_INC     - force the include path to the C wrapper
  OTEL_LIB     - force the library path to the C wrapper
  OTEL_RUNPATH - add the C wrapper RUNPATH to the executable

Example build with OTel and debug enabled:

  make -j8 USE_OTEL=1 OTEL_DEBUG=1 TARGET=linux-glibc
2026-04-13 09:23:26 +02:00
.github CI: github: add the architecture to the cache key for vtest2 2026-04-08 11:16:59 +02:00
addons MEDIUM: otel: added OpenTelemetry filter skeleton 2026-04-13 09:23:26 +02:00
admin CLEANUP: fix typos and spelling in comments and documentation 2026-03-30 09:24:19 +02:00
dev CLEANUP: fix typos and spelling in comments and documentation 2026-03-30 09:24:19 +02:00
doc DOC: update draft link for QMux protocol 2026-04-10 10:20:52 +02:00
examples MINOR: ssl/log: add keylog format variables and env vars 2026-04-01 16:28:49 +02:00
include MEDIUM: otel: added OpenTelemetry filter skeleton 2026-04-13 09:23:26 +02:00
reg-tests REGTESTS: lua: add tune.lua.openlibs to all Lua reg-tests 2026-04-09 14:32:12 +02:00
scripts CI: VTest build with git clone + cache 2026-04-07 18:35:23 +02:00
src MEDIUM: otel: added OpenTelemetry filter skeleton 2026-04-13 09:23:26 +02:00
tests TESTS: quic: add unit-tests for QUIC TX part 2025-09-08 14:49:03 +02:00
.cirrus.yml CI: cirrus-ci: bump FreeBSD image to 14-3 2025-10-09 14:06:48 +02:00
.gitattributes MINOR: Configure the cpp userdiff driver for *.[ch] in .gitattributes 2021-02-22 18:17:57 +01:00
.gitignore MINOR: tevt/dev: Add term_events tool 2025-01-31 10:41:50 +01:00
.mailmap DOC: update Tim's address in .mailmap 2021-09-16 09:14:14 +02:00
.travis.yml MEDIUM: mworker: remove USE_SYSTEMD requirement for -Ws 2024-11-20 12:07:38 +01:00
BRANCHES DOC: clarify the experimental status for certain features 2025-10-17 18:41:13 +02:00
BSDmakefile BUILD: makefile: commit the tiny FreeBSD makefile stub 2023-05-24 17:17:36 +02:00
CHANGELOG [RELEASE] Released version 3.4-dev8 2026-04-03 11:46:05 +02:00
CONTRIBUTING CLEANUP: assorted typo fixes in the code and comments 2025-04-02 11:12:20 +02:00
INSTALL MINOR: version: mention that it's development again 2025-11-26 16:11:47 +01:00
LICENSE LICENSE: add licence exception for OpenSSL 2012-09-07 13:52:26 +02:00
MAINTAINERS MAJOR: spoe: Let the SPOE back into the game 2024-05-22 09:04:38 +02:00
Makefile MEDIUM: otel: added OpenTelemetry filter skeleton 2026-04-13 09:23:26 +02:00
README.md DOC: remove openssl no-deprecated CI image 2026-02-19 10:39:23 +01:00
SUBVERS BUILD: use format tags in VERDATE and SUBVERS files 2013-12-10 11:22:49 +01:00
VERDATE [RELEASE] Released version 3.4-dev8 2026-04-03 11:46:05 +02:00
VERSION [RELEASE] Released version 3.4-dev8 2026-04-03 11:46:05 +02:00

HAProxy

alpine/musl AWS-LC Illumos NetBSD FreeBSD VTest

HAProxy logo

HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.

Installation

The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.

Getting help

The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.

The issue tracker is only for bug reports or feature requests.

Documentation

The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.

Please refer to the following files depending on what you're looking for:

  • INSTALL for instructions on how to build and install HAProxy
  • BRANCHES to understand the project's life cycle and what version to use
  • LICENSE for the project's license
  • CONTRIBUTING for the process to follow to submit contributions

The more detailed documentation is located into the doc/ directory:

License

HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.