[CONFIGURATION] Implement declarative configuration (config.yaml)

.github/workflows/ci.yml

@@ -182,6 +182,48 @@ jobs:
       run: |
         (cd ./functional/otlp; ./run_test.sh)
 
+  cmake_clang_yaml_config:
+    name: CMake clang 18 (maintainer mode, yaml config)
+    runs-on: ubuntu-24.04
+    env:
+      CC: /usr/bin/clang-18
+      CXX: /usr/bin/clang++-18
+      CXX_STANDARD: '14'
+    steps:
+    - name: Harden the runner (Audit all outbound calls)
+      uses: step-security/harden-runner@6c439dc8bdf85cadbbce9ed30d1c7b959517bc49 # v2.12.2
+      with:
+        egress-policy: audit
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+      with:
+        submodules: 'recursive'
+    - name: setup
+      run: |
+        sudo -E ./ci/setup_ci_environment.sh
+    - name: install dependencies
+      run: |
+        sudo -E ./ci/install_thirdparty.sh --install-dir /usr/local --tags-file third_party_release
+    - name: install ryml
+      run: |
+        sudo -E ./ci/install_ryml.sh
+    - name: run cmake clang (maintainer mode, sync)
+      run: |
+        ./ci/do_ci.sh cmake.maintainer.yaml.test
+    - name: install shelltest
+      run: sudo apt update && sudo apt-get install -y shelltestrunner
+    - name: generate test cert
+      env:
+        CFSSL_VERSION: 1.6.3
+      run: |
+        sudo -E ./tools/setup-cfssl.sh
+        (cd ./functional/cert; ./generate_cert.sh)
+    - name: run otlp func test
+      run: |
+        (cd ./functional/otlp; ./run_test.sh)
+    - name: run configuration func test
+      run: |
+        (cd ./functional/configuration; ./run_test.sh)
+
   cmake_clang_maintainer_async_test:
     name: CMake clang 18 (maintainer mode, async)
     runs-on: ubuntu-24.04

.github/workflows/clang-tidy.yaml

@@ -17,9 +17,9 @@ jobs:
       matrix:
         include:
           - cmake_options: all-options-abiv1-preview
-            warning_limit: 61
+            warning_limit: 66
           - cmake_options: all-options-abiv2-preview
-            warning_limit: 61
+            warning_limit: 66
     steps:
       - name: Harden the runner (Audit all outbound calls)
         uses: step-security/harden-runner@ec9f2d5744a09debf3a187a3f4f675c53b671911 # v2.13.0
@@ -48,6 +48,7 @@ jobs:
           libgmock-dev \
           libgtest-dev \
           libbenchmark-dev
+          sudo ./ci/install_ryml.sh
 
           if ! command -v clang-tidy &> /dev/null; then
             echo "clang-tidy could not be found"

.github/workflows/iwyu.yml

@@ -53,9 +53,15 @@ jobs:
             llvm-dev \
             libclang-dev \
             cmake
+
+      - name: Install rapidyaml
+        run: |
+          sudo ./ci/install_ryml.sh
+
       - name: Install include-what-you-use
         run: |
           sudo ./ci/install_iwyu.sh
+
       - name: Prepare CMake
         env:
           CC: clang

.iwyu.imp

@@ -11,6 +11,17 @@
   { "include": ["<bits/types/struct_tm.h>", "private", "<time.h>", "public"] },
   { "include": ["<bits/types/struct_FILE.h>", "private", "<stdio.h>", "public"] },
 
+  # Work around for ryml
+  { "include": ["<c4/std/string.hpp>", "private", "<ryml_std.hpp>", "public"] },
+
+  { "include": ["<c4/yml/node.hpp>", "private", "<ryml.hpp>", "public"] },
+  { "include": ["<c4/yml/parse.hpp>", "private", "<ryml.hpp>", "public"] },
+  { "include": ["<c4/yml/parse_engine.hpp>", "private", "<ryml.hpp>", "public"] },
+  { "include": ["<c4/yml/tree.hpp>", "private", "<ryml.hpp>", "public"] },
+  { "include": ["<c4/yml/event_handler_tree.hpp>", "private", "<ryml.hpp>", "public"] },
+  { "include": ["<c4/substr.hpp>", "private", "<ryml.hpp>", "public"] },
+  { "include": ["<c4/substr_fwd.hpp>", "private", "<ryml.hpp>", "public"] },
+
   # Local opentelemetry-cpp style
 
   # We prefer to include <gtest/gtest.h> for simplicity

CMakeLists.txt

@@ -77,6 +77,8 @@ endif()
 option(WITH_ABI_VERSION_1 "ABI version 1" ON)
 option(WITH_ABI_VERSION_2 "EXPERIMENTAL: ABI version 2 preview" OFF)
 
+option(WITH_CONFIGURATION "EXPERIMENTAL: YAML configuration file" OFF)
+
 file(READ "${CMAKE_CURRENT_LIST_DIR}/api/include/opentelemetry/version.h"
      OPENTELEMETRY_CPP_HEADER_VERSION_H)
 
@@ -382,6 +384,18 @@ if((NOT WITH_API_ONLY) AND USE_NLOHMANN_JSON)
   include("${opentelemetry-cpp_SOURCE_DIR}/cmake/nlohmann-json.cmake")
 endif()
 
+#
+# Do we need RapidYaml ?
+#
+
+if((NOT WITH_API_ONLY) AND WITH_CONFIGURATION)
+  find_package(ryml 0.7.2 REQUIRED)
+  message(
+    STATUS
+      "Found ryml: include ${RYML_INCLUDE_DIR}, lib ${RYML_LIB_DIR}, version ${ryml_VERSION}"
+  )
+endif()
+
 #
 # Do we need OpenTracing ?
 #

api/include/opentelemetry/common/string_util.h

@@ -3,6 +3,8 @@
 
 #pragma once
 
+#include <ctype.h>
+
 #include "opentelemetry/nostd/string_view.h"
 #include "opentelemetry/version.h"
 

ci/do_ci.sh

@@ -218,6 +218,31 @@ elif [[ "$1" == "cmake.maintainer.abiv2.test" ]]; then
   eval "$MAKE_COMMAND"
   make test
   exit 0
+elif [[ "$1" == "cmake.maintainer.yaml.test" ]]; then
+  cd "${BUILD_DIR}"
+  rm -rf *
+  cmake "${CMAKE_OPTIONS[@]}"  \
+        -DWITH_OTLP_HTTP=ON \
+        -DWITH_OTLP_GRPC=ON \
+        -DWITH_OTLP_FILE=ON \
+        -DWITH_PROMETHEUS=ON \
+        -DWITH_EXAMPLES=ON \
+        -DWITH_EXAMPLES_HTTP=ON \
+        -DWITH_ZIPKIN=ON \
+        -DBUILD_W3CTRACECONTEXT_TEST=ON \
+        -DWITH_ELASTICSEARCH=ON \
+        -DWITH_METRICS_EXEMPLAR_PREVIEW=ON \
+        -DWITH_ASYNC_EXPORT_PREVIEW=OFF \
+        -DOTELCPP_MAINTAINER_MODE=ON \
+        -DWITH_NO_DEPRECATED_CODE=ON \
+        -DWITH_OTLP_HTTP_COMPRESSION=ON \
+        -DWITH_OTLP_RETRY_PREVIEW=ON \
+        -DWITH_THREAD_INSTRUMENTATION_PREVIEW=ON \
+        -DWITH_CONFIGURATION=ON \
+        "${SRC_DIR}"
+  eval "$MAKE_COMMAND"
+  make test
+  exit 0
 elif [[ "$1" == "cmake.with_async_export.test" ]]; then
   cd "${BUILD_DIR}"
   rm -rf *

ci/install_ryml.sh

@@ -0,0 +1,32 @@
+#!/bin/bash
+
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+set -ex
+export DEBIAN_FRONTEND=noninteractive
+[ -z "${RYML_VERSION}" ] && export RYML_VERSION="v0.9.0"
+
+BUILD_DIR=/tmp/
+INSTALL_DIR=/usr/local/
+pushd $BUILD_DIR
+git clone --recursive -b ${RYML_VERSION} https://github.com/biojppm/rapidyaml.git
+
+cd rapidyaml
+RYML_BUILD_OPTIONS=(
+    "-DBUILD_TESTING=OFF"
+    "-DCMAKE_POSITION_INDEPENDENT_CODE=ON"
+    "-DCMAKE_INSTALL_PREFIX=$INSTALL_DIR"
+)
+
+if [ ! -z "${CXX_STANDARD}" ]; then
+    RYML_BUILD_OPTIONS=(${RYML_BUILD_OPTIONS[@]} "-DCMAKE_CXX_STANDARD=${CXX_STANDARD}")
+fi
+
+mkdir build && pushd build
+cmake "${RYML_BUILD_OPTIONS[@]}" ..
+make -j $(nproc)
+make install
+popd
+popd
+export PATH=${INSTALL_DIR}/bin:$PATH  # ensure to use the installed ryml

examples/CMakeLists.txt

@@ -31,3 +31,7 @@ add_subdirectory(multi_processor)
 if(WITH_EXAMPLES_HTTP)
   add_subdirectory(http)
 endif()
+
+if(WITH_CONFIGURATION)
+  add_subdirectory(configuration)
+endif()

examples/configuration/CMakeLists.txt

@@ -0,0 +1,86 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+if(DEFINED OPENTELEMETRY_BUILD_DLL)
+  add_definitions(-DOPENTELEMETRY_BUILD_IMPORT_DLL)
+endif()
+
+include_directories(${CMAKE_SOURCE_DIR}/sdk/include)
+
+add_executable(
+  example_yaml
+  main.cc
+  custom_sampler.cc
+  custom_sampler_builder.cc
+  custom_span_exporter.cc
+  custom_span_exporter_builder.cc
+  custom_span_processor.cc
+  custom_span_processor_builder.cc
+  custom_push_metric_exporter.cc
+  custom_push_metric_exporter_builder.cc
+  custom_pull_metric_exporter.cc
+  custom_pull_metric_exporter_builder.cc
+  custom_log_record_exporter.cc
+  custom_log_record_exporter_builder.cc
+  custom_log_record_processor.cc
+  custom_log_record_processor_builder.cc)
+
+target_link_libraries(
+  example_yaml
+  ${CMAKE_THREAD_LIBS_INIT}
+  common_metrics_foo_library
+  common_logs_foo_library
+  opentelemetry_exporter_ostream_span_builder
+  opentelemetry_exporter_ostream_metrics_builder
+  opentelemetry_exporter_ostream_logs_builder)
+
+if(WITH_OTLP_HTTP)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/otlp/include)
+  add_definitions(-DOTEL_HAVE_OTLP_HTTP)
+  target_link_libraries(example_yaml opentelemetry_exporter_otlp_http_builder)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_otlp_http_log_builder)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_otlp_http_metric_builder)
+endif()
+
+if(WITH_OTLP_GRPC)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/otlp/include)
+  add_definitions(-DOTEL_HAVE_OTLP_GRPC)
+  target_link_libraries(example_yaml opentelemetry_exporter_otlp_grpc_builder)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_otlp_grpc_log_builder)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_otlp_grpc_metrics_builder)
+endif()
+
+if(WITH_OTLP_FILE)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/otlp/include)
+  add_definitions(-DOTEL_HAVE_OTLP_FILE)
+  target_link_libraries(example_yaml opentelemetry_exporter_otlp_file_builder)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_otlp_file_log_builder)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_otlp_file_metric_builder)
+endif()
+
+if(WITH_ZIPKIN)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/zipkin/include)
+  add_definitions(-DOTEL_HAVE_ZIPKIN)
+  target_link_libraries(example_yaml
+                        opentelemetry_exporter_zipkin_trace_builder)
+endif()
+
+if(WITH_PROMETHEUS)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/prometheus/include)
+  add_definitions(-DOTEL_HAVE_PROMETHEUS)
+  target_link_libraries(example_yaml opentelemetry_exporter_prometheus_builder)
+endif()
+
+if(DEFINED OPENTELEMETRY_BUILD_DLL)
+  target_link_libraries(example_yaml opentelemetry_cpp)
+else()
+  target_link_libraries(
+    example_yaml opentelemetry_configuration opentelemetry_common
+    opentelemetry_trace opentelemetry_logs)
+endif()

examples/configuration/anchors.yaml

@@ -0,0 +1,45 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+# anchors.yaml demonstrates anchor substitution to reuse OTLP exporter configuration across signals.
+
+file_format: "0.1"
+exporters:
+  otlp: &otlp-exporter
+    protocol: http/protobuf
+    endpoint: http://localhost:4318
+    certificate: /app/cert.pem
+    client_key: /app/cert.pem
+    client_certificate: /app/cert.pem
+    headers:
+      api-key: !!str 1234
+    compression: gzip
+    timeout: 10000
+
+logger_provider:
+  processors:
+    - batch:
+        exporter:
+          otlp:
+            # expand the otlp-exporter anchor
+            <<: *otlp-exporter
+
+meter_provider:
+  readers:
+    - periodic:
+        interval: 5000
+        timeout: 30000
+        exporter:
+          otlp:
+            # expand the otlp-exporter anchor and add metric specific configuration
+            <<: *otlp-exporter
+            temporality_preference: delta
+            default_histogram_aggregation: base2_exponential_bucket_histogram
+
+tracer_provider:
+  processors:
+    - batch:
+        exporter:
+          otlp:
+            # expand the otlp-exporter anchor
+            <<: *otlp-exporter