[RFC] Poc config yaml

.github/workflows/ci.yml

@@ -160,6 +160,40 @@ 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
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        submodules: 'recursive'
+    - name: setup
+      env:
+        CC: /usr/bin/clang-18
+        CXX: /usr/bin/clang++-18
+        PROTOBUF_VERSION: 21.12
+      run: |
+        sudo apt remove needrestart #refer: https://github.com/actions/runner-images/issues/9937
+        sudo -E ./ci/setup_googletest.sh
+        sudo -E ./ci/setup_ci_environment.sh
+        sudo -E ./ci/install_protobuf.sh
+        sudo -E ./ci/install_ryml.sh
+    - name: run cmake clang (maintainer mode, sync)
+      env:
+        CC: /usr/bin/clang-18
+        CXX: /usr/bin/clang++-18
+      run: |
+        ./ci/do_ci.sh cmake.maintainer.yaml.test
+    - 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 func test
+      run: |
+        (cd ./functional/otlp; ./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

@@ -32,6 +32,7 @@ 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"
@@ -61,6 +62,7 @@ jobs:
             -DBUILD_W3CTRACECONTEXT_TEST=ON \
             -DWITH_METRICS_EXEMPLAR_PREVIEW=ON \
             -DWITH_ASYNC_EXPORT_PREVIEW=ON \
+            -DWITH_CONFIGURATION=ON \
             -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
 
       - name: Run clang-tidy

.github/workflows/iwyu.yml

@@ -30,6 +30,7 @@ jobs:
             libgmock-dev \
             libgtest-dev \
             libbenchmark-dev
+          sudo ./ci/install_ryml.sh
 
       - name: Prepare CMake
         run: |
@@ -39,6 +40,7 @@ jobs:
             -DCMAKE_CXX_STANDARD=14 \
             -DWITH_STL=CXX14 \
             -DCMAKE_CXX_INCLUDE_WHAT_YOU_USE="include-what-you-use;-w;-Xiwyu;--mapping_file=${TOPDIR}/.iwyu.imp;" \
+            -DWITH_CONFIGURATION=ON \
             -DBUILD_TESTING=ON \
             -DBUILD_W3CTRACECONTEXT_TEST=ON \
             -DWITH_OTLP_GRPC=OFF \

.iwyu.imp

@@ -7,6 +7,15 @@
   # Work around for C++ STL
   { "include": ["<bits/chrono.h>", "private", "<chrono>", "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/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

@@ -109,6 +109,8 @@ 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)
 
@@ -500,6 +502,18 @@ if((NOT WITH_API_ONLY) AND USE_NLOHMANN_JSON)
   include(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()
+
 if(OTELCPP_MAINTAINER_MODE)
   if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     message(STATUS "Building with gcc in maintainer mode.")

ci/do_ci.sh

@@ -204,6 +204,29 @@ 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_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_CONFIGURATION=ON \
+        ${IWYU} \
+        "${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="v0.7.2"
+
+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

@@ -29,3 +29,7 @@ add_subdirectory(multi_processor)
 if(WITH_EXAMPLES_HTTP)
   add_subdirectory(http)
 endif()
+
+if(WITH_CONFIGURATION)
+  add_subdirectory(yaml)
+endif()

examples/yaml/CMakeLists.txt

@@ -0,0 +1,59 @@
+# 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)
+
+target_link_libraries(
+  example_yaml
+  ${CMAKE_THREAD_LIBS_INIT}
+  common_metrics_foo_library
+  common_logs_foo_library
+  opentelemetry_exporter_ostream_span
+  opentelemetry_exporter_ostream_metrics
+  opentelemetry_exporter_ostream_logs)
+
+if(WITH_OTLP_HTTP)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/otlp/include)
+  add_definitions(-DOTEL_HAVE_OTLP_HTTP)
+  target_link_libraries(example_yaml opentelemetry_otlp_http_builder)
+endif()
+
+if(WITH_OTLP_GRPC)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/otlp/include)
+  add_definitions(-DOTEL_HAVE_OTLP_GRPC)
+  target_link_libraries(example_yaml opentelemetry_otlp_grpc_builder)
+endif()
+
+if(WITH_ZIPKIN)
+  include_directories(${CMAKE_SOURCE_DIR}/exporters/zipkin/include)
+  add_definitions(-DOTEL_HAVE_ZIPKIN)
+  target_link_libraries(example_yaml opentelemetry_exporter_zipkin_trace)
+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)
+endif()
+
+if(DEFINED OPENTELEMETRY_BUILD_DLL)
+  target_link_libraries(example_yaml opentelemetry_cpp)
+else()
+  target_link_libraries(
+    example_yaml opentelemetry_configuration opentelemetry_init
+    opentelemetry_common opentelemetry_trace opentelemetry_logs)
+endif()

examples/yaml/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

examples/yaml/custom_sampler.cc

@@ -0,0 +1,36 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include <map>
+#include <memory>
+
+#include "opentelemetry/common/attribute_value.h"
+#include "opentelemetry/trace/span_context.h"
+#include "opentelemetry/trace/trace_state.h"
+
+#include "custom_sampler.h"
+
+opentelemetry::sdk::trace::SamplingResult CustomSampler::ShouldSample(
+    const opentelemetry::trace::SpanContext &parent_context,
+    opentelemetry::trace::TraceId /* trace_id */,
+    opentelemetry::nostd::string_view /* name */,
+    opentelemetry::trace::SpanKind /* span_kind */,
+    const opentelemetry::common::KeyValueIterable & /* attributes */,
+    const opentelemetry::trace::SpanContextKeyValueIterable & /* links */) noexcept
+{
+  if (!parent_context.IsValid())
+  {
+    return {opentelemetry::sdk::trace::Decision::RECORD_AND_SAMPLE, nullptr,
+            opentelemetry::trace::TraceState::GetDefault()};
+  }
+  else
+  {
+    return {opentelemetry::sdk::trace::Decision::RECORD_AND_SAMPLE, nullptr,
+            parent_context.trace_state()};
+  }
+}
+
+opentelemetry::nostd::string_view CustomSampler::GetDescription() const noexcept
+{
+  return "CustomSampler";
+}

examples/yaml/custom_sampler.h

@@ -0,0 +1,31 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+
+#include <string>
+
+#include "opentelemetry/common/key_value_iterable.h"
+#include "opentelemetry/nostd/string_view.h"
+#include "opentelemetry/sdk/trace/sampler.h"
+#include "opentelemetry/trace/span_context.h"
+#include "opentelemetry/trace/span_context_kv_iterable.h"
+#include "opentelemetry/trace/span_metadata.h"
+#include "opentelemetry/trace/trace_id.h"
+
+class CustomSampler : public opentelemetry::sdk::trace::Sampler
+{
+public:
+  CustomSampler(const std::string & /* comment */) {}
+  ~CustomSampler() override = default;
+
+  opentelemetry::sdk::trace::SamplingResult ShouldSample(
+      const opentelemetry::trace::SpanContext &parent_context,
+      opentelemetry::trace::TraceId trace_id,
+      opentelemetry::nostd::string_view name,
+      opentelemetry::trace::SpanKind span_kind,
+      const opentelemetry::common::KeyValueIterable &attributes,
+      const opentelemetry::trace::SpanContextKeyValueIterable &links) noexcept override;
+
+  opentelemetry::nostd::string_view GetDescription() const noexcept override;
+};

examples/yaml/custom_sampler_builder.cc

@@ -0,0 +1,28 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#include <string>
+
+#include "opentelemetry/sdk/configuration/document_node.h"
+#include "opentelemetry/sdk/init/registry.h"
+
+#include "custom_sampler.h"
+#include "custom_sampler_builder.h"
+
+std::unique_ptr<opentelemetry::sdk::trace::Sampler> CustomSamplerBuilder::Build(
+    const opentelemetry::sdk::configuration::ExtensionSamplerConfiguration *model) const
+{
+  // Read yaml attributes
+  std::string comment = model->node->GetRequiredString("comment");
+
+  std::unique_ptr<opentelemetry::sdk::trace::Sampler> sdk(new CustomSampler(comment));
+
+  return sdk;
+}
+
+static CustomSamplerBuilder singleton;
+
+void CustomSamplerBuilder::Register(opentelemetry::sdk::init::Registry *registry)
+{
+  registry->AddExtensionSamplerBuilder("my_custom_sampler", &singleton);
+}