Fluent OTel (OpenTelemetry) Proto files

This projects builds a static library that provides C interfaces for OpenTelemetry proto files data model and also includes some helper utilities.

In the source, the .proto files are already included in their C version, so here you will find instructions for:

build this as a static library
regenerate C interfaces from .proto files

The project exposes the following build options:

Build static library

To get start just clone this repository

git clone https://github.com/fluent/fluent-otel-proto

Join the build directory and compile:

cd fluent-otel-proto/build
cmake ../

By default an example test gets available:

examples/test-api
- opentelemetry proto 'common'  :     found
- opentelemetry proto 'resource':     found
- opentelemetry proto 'trace'   :     found
- opentelemetry proto 'logs'    :     found
- opentelemetry proto 'metrics' :     found
- opentelemetry proto 'profiles':     found

Regenerate C files

To regenerate the C files inside this repo, you need to main dependencies or repositories:

Download dependencies

0. protobuf (https://github.com/protocolbuffers/protobuf)

This version of protobuf-c to build in the next steps required an updated version of protobuf, at this moment this needs to be compiled manually since distros ships a very old version, here are the required steps:

cd /tmp
git clone --depth 1 --branch v5.26.1 https://github.com/protocolbuffers/protobuf.git protobuf-src
cd protobuf-src
git submodule update --init --recursive
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release \
         -Dprotobuf_BUILD_TESTS=OFF \
         -DCMAKE_INSTALL_PREFIX=/usr/local
make
sudo make install
sudo ldconfig

1. Protobuf-c

The repository fluent/protobuf-c is a fork of the official protobuf-c that includes upstream PR #781 to support optional feature from proto3. This feature is only required by the OpenTelemetry Metrics data model.

Download and install protobuf-c by running the following commands:

git clone https://github.com/fluent/protobuf-c
cd protobuf-c
./autogen.sh
./configure PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig:/usr/local/lib/pkgconfig --prefix=/opt/protobuf-c
make
sudo make install

2. OpenTelemetry Proto

Download the main repository with the following command:

git clone https://github.com/open-telemetry/opentelemetry-proto

3. Clone this repository

git clone https://github.com/fluent/fluent-otel-proto

4. Regenerate C Files

The CMake command will require the following variable definitions to succeed in the C files regeneration:

Variable name	Description
FLUENT_PROTO_REGENERATE	Enable the C source file regeneration. Disabled by default.
PROTOBUF_C_SOURCE_DIR	Absolute path of the directory containing the sources of `protobuf-c` downloaded in Step 1. NOTE: this is the source code path, not where the binaries were installed.
OTEL_PROTO_DIR	Absolute path of the directory containing the sources of `opentelemetry-proto` downloaded in Step 2.

In addition, the following build options are available if you desire to enable/disable certain feature:

Build Option	Description	Default
FLUENT_PROTO_COMMON	Include the regeneration of C interfaces for `common.proto` file.	On
FLUENT_PROTO_RESOURCE	Include the regeneration of C interface for `resource.proto` file.	On
FLUENT_PROTO_TRACE	Include the regeneration of C interfaces for `trace.proto` and `trace_service.proto` files.	On
FLUENT_PROTO_LOGS	Include the regeneration of C interfaces for `logs.proto` and `logs_service.proto` files.	On
FLUENT_PROTO_METRICS	Include the regeneration of C interfaces for `metrics.proto` and `metrics_service.proto` files.	On
FLUENT_PROTO_PROFILES	Include the regeneartion of C inter for `profiles.proto`	On

5. Example

Get into this project source code directory:

cd fluent-otel-proto/build/

Run CMake:

cmake -DFLUENT_PROTO_REGENERATE=ON \
      -DPROTOBUF_C_SOURCE_DIR=/tmp/protobuf-c \
      -DOTEL_PROTO_DIR=/tmp/opentelemetry-proto \
      ../

now build by running make command.