Add Prometheus Exporter: Step 1

.github/workflows/ci.yml

@@ -18,6 +18,8 @@ jobs:
         sudo ./ci/setup_ci_environment.sh
     - name: run tests
       run: ./ci/do_ci.sh cmake.test
+    - name: run prometheus exporter tests
+      run: ./ci/do_ci.sh cmake.exporter.prometheus.test
 
   cmake_test_cxx20:
     name: CMake C++20 test

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "third_party/prometheus-cpp"]
+	path = third_party/prometheus-cpp
+	url = https://github.com/jupp0r/prometheus-cpp.git

CMakeLists.txt

@@ -13,6 +13,9 @@ endif()
 option(WITH_OTPROTOCOL
        "Whether to include the OpenTelemetry Protocol in the SDK" OFF)
 
+option(WITH_PROMETHEUS "Whether to include the Prometheus Client in the SDK"
+       OFF)
+
 set(WITH_PROTOBUF OFF)
 if(WITH_OTPROTOCOL)
   set(WITH_PROTOBUF ON)

WORKSPACE

@@ -88,3 +88,17 @@ http_archive(
         "https://github.com/nlohmann/json/releases/download/v3.6.1/include.zip",
     ],
 )
+
+# C++ Prometheus Client library.
+load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive", "http_file")
+
+http_archive(
+    name = "com_github_jupp0r_prometheus_cpp",
+    sha256 = "85ad6fea0f0dcb413104366b7d6109acdb015aff8767945511c5cad8202a28a6",
+    strip_prefix = "prometheus-cpp-0.9.0",
+    urls = ["https://github.com/jupp0r/prometheus-cpp/archive/v0.9.0.tar.gz"],
+)
+
+load("@com_github_jupp0r_prometheus_cpp//bazel:repositories.bzl", "prometheus_cpp_repositories")
+
+prometheus_cpp_repositories()

ci/do_ci.sh

@@ -40,6 +40,33 @@ elif [[ "$1" == "cmake.exporter.otprotocol.test" ]]; then
   make
   make test
   exit 0
+elif [[ "$1" == "cmake.exporter.prometheus.test" ]]; then
+#  export DEBIAN_FRONTEND=noninteractive
+#  apt-get update
+#  apt-get install sudo
+#  apt-get install zlib1g-dev
+#  apt-get -y install libcurl4-openssl-dev
+  cd third_party
+  git clone https://github.com/jupp0r/prometheus-cpp
+  cd prometheus-cpp
+  git checkout v0.9.0
+  git submodule init
+  git submodule update
+  mkdir _build && cd _build
+  cmake .. -DBUILD_SHARED_LIBS=ON
+  make -j 4
+  sudo make install
+
+  cd "${BUILD_DIR}"
+  rm -rf *
+
+  cmake -DCMAKE_BUILD_TYPE=Debug  \
+        -DWITH_PROMETHEUS=ON \
+        -DCMAKE_CXX_FLAGS="-Werror" \
+        "${SRC_DIR}"
+  make
+  make test
+  exit 0
 elif [[ "$1" == "cmake.test_example_plugin" ]]; then
   # Build the plugin
   cd "${BUILD_DIR}"
@@ -83,8 +110,10 @@ elif [[ "$1" == "bazel.legacy.test" ]]; then
   bazel test $BAZEL_TEST_OPTIONS -- //... -//exporters/otlp/...
   exit 0
 elif [[ "$1" == "bazel.noexcept" ]]; then
-  bazel build --copt=-fno-exceptions $BAZEL_OPTIONS //...
-  bazel test --copt=-fno-exceptions $BAZEL_TEST_OPTIONS //...
+  # there are some exceptions and error handling code from the Prometheus Client
+  # that make this test always fail. ignore Prometheus exporter in the noexcept here.
+  bazel build --copt=-fno-exceptions $BAZEL_OPTIONS -- //... -//exporters/prometheus/...
+  bazel test --copt=-fno-exceptions $BAZEL_TEST_OPTIONS -- //... -//exporters/prometheus/...
   exit 0
 elif [[ "$1" == "bazel.asan" ]]; then
   bazel test --config=asan $BAZEL_TEST_OPTIONS //...

ci/setup_cmake.sh

@@ -2,10 +2,15 @@
 
 set -e
 
+export DEBIAN_FRONTEND=noninteractive
+apt-get update
 apt-get install --no-install-recommends --no-install-suggests -y \
                 cmake \
                 libbenchmark-dev \
-                libgtest-dev
+                libgtest-dev \
+                zlib1g-dev \
+                sudo \
+                libcurl4-openssl-dev
 
 # Follows these instructions for setting up gtest
 # https://www.eriksmistad.no/getting-started-with-google-test-on-ubuntu/

exporters/CMakeLists.txt

@@ -1,4 +1,9 @@
 if(WITH_OTPROTOCOL)
   add_subdirectory(otlp)
 endif()
+
 add_subdirectory(ostream)
+
+if(WITH_PROMETHEUS)
+  add_subdirectory(prometheus)
+endif()

exporters/prometheus/BUILD

@@ -0,0 +1,42 @@
+# Copyright 2020, OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "prometheus_utils",
+    srcs = [
+        "src/prometheus_exporter_utils.cc",
+    ],
+    hdrs = [
+        "include/opentelemetry/exporters/prometheus/prometheus_exporter_utils.h",
+    ],
+    strip_include_prefix = "include",
+    deps = [
+        "//api",
+        "//sdk:headers",
+        "@com_github_jupp0r_prometheus_cpp//core",
+    ],
+)
+
+cc_test(
+    name = "prometheus_exporter_utils_test",
+    srcs = [
+        "test/prometheus_exporter_utils_test.cc",
+    ],
+    deps = [
+        ":prometheus_utils",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

exporters/prometheus/CMakeLists.txt

@@ -0,0 +1,22 @@
+# Copyright 2020, OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+include_directories(include)
+
+find_package(prometheus-cpp CONFIG REQUIRED)
+add_library(prometheus_exporter src/prometheus_exporter_utils.cc)
+
+if(BUILD_TESTING)
+  add_subdirectory(test)
+endif()

exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter_utils.h

@@ -0,0 +1,182 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "opentelemetry/sdk/metrics/record.h"
+#include "prometheus/metric_family.h"
+
+namespace metric_sdk = opentelemetry::sdk::metrics;
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace exporter
+{
+namespace prometheus
+{
+/**
+ * The Prometheus Utils contains utility functions for Prometheus Exporter
+ */
+class PrometheusExporterUtils
+{
+public:
+  /**
+   * Helper function to convert OpenTelemetry metrics data collection
+   * to Prometheus metrics data collection
+   *
+   * @param records a collection of metrics in OpenTelemetry
+   * @return a collection of translated metrics that is acceptable by Prometheus
+   */
+  static std::vector<::prometheus::MetricFamily> TranslateToPrometheus(
+      const std::vector<metric_sdk::Record> &records);
+
+private:
+  /**
+   * Set value to metric family according to record
+   */
+  static void SetMetricFamily(metric_sdk::Record &record,
+                              ::prometheus::MetricFamily *metric_family);
+
+  /**
+   * Sanitize the given metric name or label according to Prometheus rule.
+   *
+   * This function is needed because names in OpenTelemetry can contain
+   * alphanumeric characters, '_', '.', and '-', whereas in Prometheus the
+   * name should only contain alphanumeric characters and '_'.
+   */
+  static std::string SanitizeNames(std::string name);
+
+  /**
+   * Set value to metric family for different aggregator
+   */
+  template <typename T>
+  static void SetMetricFamilyByAggregator(std::shared_ptr<metric_sdk::Aggregator<T>> aggregator,
+                                          std::string labels_str,
+                                          ::prometheus::MetricFamily *metric_family);
+
+  /**
+   * Translate the OTel metric type to Prometheus metric type
+   */
+  static ::prometheus::MetricType TranslateType(metric_sdk::AggregatorKind kind);
+
+  /**
+   * Set metric data for:
+   * Counter => Prometheus Counter
+   * Gauge => Prometheus Gauge
+   */
+  template <typename T>
+  static void SetData(std::vector<T> values,
+                      const std::string &labels,
+                      ::prometheus::MetricType type,
+                      std::chrono::nanoseconds time,
+                      ::prometheus::MetricFamily *metric_family);
+
+  /**
+   * Set metric data for:
+   * Histogram => Prometheus Histogram
+   */
+  template <typename T>
+  static void SetData(std::vector<T> values,
+                      const std::vector<double> &boundaries,
+                      const std::vector<int> &counts,
+                      const std::string &labels,
+                      std::chrono::nanoseconds time,
+                      ::prometheus::MetricFamily *metric_family);
+
+  /**
+   * Set metric data for:
+   * MinMaxSumCount => Prometheus Gauge
+   * Use Average (sum / count) as the gauge metric
+   */
+  static void SetData(double value,
+                      const std::string &labels,
+                      std::chrono::nanoseconds time,
+                      ::prometheus::MetricFamily *metric_family);
+
+  /**
+   * Set metric data for:
+   * Exact => Prometheus Summary
+   * Sketch => Prometheus Summary
+   */
+  template <typename T>
+  static void SetData(std::vector<T> values,
+                      metric_sdk::AggregatorKind kind,
+                      const std::vector<T> &quantiles,
+                      const std::string &labels,
+                      std::chrono::nanoseconds time,
+                      ::prometheus::MetricFamily *metric_family,
+                      bool do_quantile,
+                      std::vector<double> quantile_points);
+
+  /**
+   * Set time and labels to metric data
+   */
+  static void SetMetricBasic(::prometheus::ClientMetric &metric,
+                             std::chrono::nanoseconds time,
+                             const std::string &labels);
+
+  /**
+   * Parse a string of labels (key:value) into a vector of pairs
+   * {,}
+   * {l1:v1,l2:v2,...,}
+   */
+  static std::vector<std::pair<std::string, std::string>> ParseLabel(std::string labels);
+
+  /**
+   * Build a quantiles vector from aggregator
+   */
+  template <typename T>
+  static std::vector<T> GetQuantilesVector(std::shared_ptr<metric_sdk::Aggregator<T>> aggregator,
+                                           const std::vector<double> &quantile_points);
+
+  /**
+   * Handle Counter and Gauge.
+   */
+  template <typename T>
+  static void SetValue(std::vector<T> values,
+                       ::prometheus::MetricType type,
+                       ::prometheus::ClientMetric *metric);
+
+  /**
+   * Handle Gauge from MinMaxSumCount
+   */
+  static void SetValue(double value, ::prometheus::ClientMetric *metric);
+
+  /**
+   * Handle Histogram
+   */
+  template <typename T>
+  static void SetValue(std::vector<T> values,
+                       std::vector<double> boundaries,
+                       std::vector<int> counts,
+                       ::prometheus::ClientMetric *metric);
+
+  /**
+   * Handle Exact and Sketch
+   */
+  template <typename T>
+  static void SetValue(std::vector<T> values,
+                       metric_sdk::AggregatorKind kind,
+                       std::vector<T> quantiles,
+                       ::prometheus::ClientMetric *metric,
+                       bool do_quantile,
+                       const std::vector<double> &quantile_points);
+};
+}  // namespace prometheus
+}  // namespace exporter
+OPENTELEMETRY_END_NAMESPACE