haproxy/addons/otel/include/include.h
Miroslav Zagorac ea9d05de02 MEDIUM: otel: added context propagation via carrier interfaces
Added the span context injection and extraction layer that bridges the
OTel C wrapper's propagation API with HAProxy's HTTP headers and text map
carriers.

The new otelc.c module implements four public functions that wrap the
OTel C wrapper's context propagation methods: flt_otel_inject_text_map()
and flt_otel_inject_http_headers() serialize a span's context into
a text map or HTTP headers carrier for outbound propagation, while
flt_otel_extract_text_map() and flt_otel_extract_http_headers()
deserialize an inbound carrier into an otelc_span_context for parent
linking.

Each direction uses a pair of callbacks registered on the carrier
structure.  The injection writers (flt_otel_text_map_writer_set_cb and
flt_otel_http_headers_writer_set_cb) store key-value pairs emitted by the
SDK into the carrier's text map via OTELC_TEXT_MAP_ADD().  The extraction
readers (flt_otel_text_map_reader_foreach_key_cb and
flt_otel_http_headers_reader_foreach_key_cb) iterate the carrier's text
map entries and pass each pair to the SDK's handler callback.

The scope context initialization in flt_otel_scope_context_init() now
calls flt_otel_extract_http_headers() to extract the span context from the
provided text map carrier and stores it in the scope context structure,
making extracted contexts available for parent linking in subsequent span
creation.
2026-04-13 09:23:26 +02:00

50 lines
1,004 B
C

/* 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 "event.h"
#include "conf.h"
#include "conf_funcs.h"
#include "filter.h"
#include "otelc.h"
#include "parser.h"
#include "pool.h"
#include "scope.h"
#include "util.h"
#endif /* _OTEL_INCLUDE_H_ */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*
* vi: noexpandtab shiftwidth=8 tabstop=8
*/