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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
HAProxy
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:
- doc/intro.txt for a quick introduction on HAProxy
- doc/configuration.txt for the configuration's reference manual
- doc/lua.txt for the Lua's reference manual
- doc/SPOE.txt for how to use the SPOE engine
- doc/network-namespaces.txt for how to use network namespaces under Linux
- doc/management.txt for the management guide
- doc/regression-testing.txt for how to use the regression testing suite
- doc/peers.txt for the peers protocol reference
- doc/coding-style.txt for how to adopt HAProxy's coding style
- doc/internals for developer-specific documentation (not all up to date)
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.