Add Prometheus Exporter

CHANGELOG.md

@@ -15,6 +15,7 @@ Increment the:
 
 ## [Unreleased]
 
+* [EXPORTER] Prometheus Exporter ([#1031](https:/open-telemetry/opentelemetry-cpp/pull/1031))
 * [EXPORTER] Add OTLP/HTTP Log Exporter ([#1030](https:/open-telemetry/opentelemetry-cpp/pull/1030))
 
 ## [1.0.1] 2021-10-21

CMakeLists.txt

@@ -299,6 +299,24 @@ if((NOT WITH_API_ONLY)
  endif()
 endif()
 
+if(WITH_PROMETHEUS)
+ find_package(prometheus-cpp CONFIG QUIET)
+ if(NOT prometheus-cpp_FOUND)
+ message("Trying to use local prometheus-cpp from submodule")
+ if(EXISTS ${PROJECT_SOURCE_DIR}/third_party/prometheus-cpp/.git)
+ add_subdirectory(third_party/prometheus-cpp)
+ else()
+ message(
+ FATAL_ERROR
+ "\nprometheus-cpp package was not found. Please either provide it manually or clone with submodules. "
+ "To initialize, fetch and checkout any nested submodules, you can use the following command:\n"
+ "git submodule update --init --recursive")
+ endif()
+ else()
+ message("Using external prometheus-cpp")
+ endif()
+endif()
+
 if(WITH_OTLP)
  set(protobuf_MODULE_COMPATIBLE ON)
  find_package(Protobuf)

ci/do_ci.sh

@@ -35,7 +35,6 @@ BAZEL_STARTUP_OPTIONS="--output_user_root=$HOME/.cache/bazel"
 export CTEST_OUTPUT_ON_FAILURE=1
 
 if [[ "$1" == "cmake.test" ]]; then
- install_prometheus_cpp_client
  cd "${BUILD_DIR}"
  rm -rf *
  cmake -DCMAKE_BUILD_TYPE=Debug \

exporters/prometheus/BUILD

@@ -15,25 +15,26 @@
 package(default_visibility = ["//visibility:public"])
 
 cc_library(
- name = "prometheus_collector",
+ name = "prometheus_exporter",
  srcs = [
- "src/prometheus_collector.cc",
+ "src/prometheus_exporter.cc",
  ],
  hdrs = [
- "include/opentelemetry/exporters/prometheus/prometheus_collector.h",
- "include/opentelemetry/exporters/prometheus/prometheus_exporter_utils.h",
+ "include/opentelemetry/exporters/prometheus/prometheus_exporter.h",
  ],
  strip_include_prefix = "include",
  deps = [
- ":prometheus_utils",
+ ":prometheus_collector",
+ ":prometheus_exporter_utils",
  "//api",
  "//sdk:headers",
  "@com_github_jupp0r_prometheus_cpp//core",
+ "@com_github_jupp0r_prometheus_cpp//pull",
  ],
 )
 
 cc_library(
- name = "prometheus_utils",
+ name = "prometheus_exporter_utils",
  srcs = [
  "src/prometheus_exporter_utils.cc",
  ],
@@ -45,27 +46,35 @@ cc_library(
  "//api",
  "//sdk:headers",
  "@com_github_jupp0r_prometheus_cpp//core",
+ "@com_github_jupp0r_prometheus_cpp//pull",
  ],
 )
 
-cc_test(
- name = "prometheus_collector_test",
+cc_library(
+ name = "prometheus_collector",
  srcs = [
- "test/prometheus_collector_test.cc",
+ "src/prometheus_collector.cc",
  ],
+ hdrs = [
+ "include/opentelemetry/exporters/prometheus/prometheus_collector.h",
+ ],
+ strip_include_prefix = "include",
  deps = [
- ":prometheus_collector",
- "@com_google_googletest//:gtest_main",
+ ":prometheus_exporter_utils",
+ "//api",
+ "//sdk:headers",
+ "@com_github_jupp0r_prometheus_cpp//core",
+ "@com_github_jupp0r_prometheus_cpp//pull",
  ],
 )
 
 cc_test(
- name = "prometheus_exporter_utils_test",
+ name = "prometheus_exporter_test",
  srcs = [
- "test/prometheus_exporter_utils_test.cc",
+ "test/prometheus_exporter_test.cc",
  ],
  deps = [
- ":prometheus_utils",
+ ":prometheus_exporter",
  "@com_google_googletest//:gtest_main",
  ],
 )

exporters/prometheus/CMakeLists.txt

@@ -13,22 +13,26 @@
 # limitations under the License.
 
 include_directories(include)
-find_package(prometheus-cpp CONFIG REQUIRED)
-
-add_library(prometheus_exporter_deprecated src/prometheus_collector.cc
- src/prometheus_exporter_utils.cc)
+if(NOT TARGET prometheus-cpp::core)
+ find_package(prometheus-cpp CONFIG REQUIRED)
+endif()
 
+add_library(
+ prometheus_exporter_deprecated
+ src/prometheus_exporter.cc src/prometheus_collector.cc
+ src/prometheus_exporter_utils.cc)
 target_include_directories(
  prometheus_exporter_deprecated
  PUBLIC "$<BUILD_INTERFACE:${CMAKE_CURRENT_LIST_DIR}/include>"
  "$<INSTALL_INTERFACE:include>")
 
+set(PROMETHEUS_EXPORTER_TARGETS prometheus_exporter_deprecated pull core)
 target_link_libraries(
- prometheus_exporter_deprecated PUBLIC opentelemetry_metrics_deprecated
-  prometheus-cpp::core)
-
+ prometheus_exporter_deprecated
+ PUBLIC opentelemetry_metrics_deprecated prometheus-cpp::pull
+ prometheus-cpp::core)
 install(
- TARGETS prometheus_exporter_deprecated
+ TARGETS ${PROMETHEUS_EXPORTER_TARGETS}
  EXPORT "${PROJECT_NAME}-target"
  RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
  LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}

exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_collector.h

@@ -8,10 +8,10 @@
 # include <mutex>
 # include <vector>
 
+# include "opentelemetry/exporters/prometheus/prometheus_exporter_utils.h"
 # include "opentelemetry/sdk/_metrics/record.h"
 # include "prometheus/collectable.h"
 # include "prometheus/metric_family.h"
-# include "prometheus_exporter_utils.h"
 
 namespace prometheus_client = ::prometheus;
 namespace metric_sdk = opentelemetry::sdk::metrics;

exporters/prometheus/include/opentelemetry/exporters/prometheus/prometheus_exporter.h

@@ -0,0 +1,98 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+#ifdef ENABLE_METRICS_PREVIEW
+# include <memory>
+# include <string>
+# include <vector>
+
+# include "opentelemetry/exporters/prometheus/prometheus_collector.h"
+# include "opentelemetry/sdk/_metrics/exporter.h"
+# include "opentelemetry/sdk/_metrics/record.h"
+# include "opentelemetry/version.h"
+# include "prometheus/exposer.h"
+
+/**
+ * This class is an implementation of the MetricsExporter interface and
+ * exports Prometheus metrics data. Functions in this class should be
+ * called by the Controller in our data pipeline.
+ */
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+
+namespace exporter
+{
+namespace prometheus
+{
+class PrometheusExporter : public sdk::metrics::MetricsExporter
+{
+public:
+ /**
+ * Constructor - binds an exposer and collector to the exporter
+ * @param address: an address for an exposer that exposes
+ * an HTTP endpoint for the exporter to connect to
+ */
+ PrometheusExporter(std::string &address);
+
+ /**
+ * Exports a batch of Metric Records.
+ * @param records: a collection of records to export
+ * @return: returns a ReturnCode detailing a success, or type of failure
+ */
+ sdk::common::ExportResult Export(
+ const std::vector<sdk::metrics::Record> &records) noexcept override;
+
+ /**
+ * Shuts down the exporter and does cleanup.
+ * Since Prometheus is a pull based interface,
+ * we cannot serve data remaining in the intermediate
+ * collection to to client an HTTP request being sent,
+ * so we flush the data.
+ */
+ void Shutdown() noexcept;
+
+ /**
+ * @return: returns a shared_ptr to
+ * the PrometheusCollector instance
+ */
+ std::shared_ptr<PrometheusCollector> &GetCollector();
+
+ /**
+ * @return: Gets the shutdown status of the exporter
+ */
+ bool IsShutdown() const;
+
+private:
+ /**
+ * exporter shutdown status
+ */
+ bool is_shutdown_;
+
+ /**
+ * Pointer to a
+ * PrometheusCollector instance
+ */
+ std::shared_ptr<PrometheusCollector> collector_;
+
+ /**
+ * Pointer to an
+ * Exposer instance
+ */
+ std::unique_ptr<::prometheus::Exposer> exposer_;
+
+ /**
+ * friend class for testing
+ */
+ friend class PrometheusExporterTest;
+
+ /**
+ * PrometheusExporter constructor with no parameters
+ * Used for testing only
+ */
+ PrometheusExporter();
+};
+} // namespace prometheus
+} // namespace exporter
+OPENTELEMETRY_END_NAMESPACE
+#endif // ENABLE_METRICS_PREVIEW

exporters/prometheus/src/prometheus_exporter.cc

@@ -0,0 +1,110 @@
+/*
+ * 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.
+ */
+
+#ifdef ENABLE_METRICS_PREVIEW
+# include "opentelemetry/exporters/prometheus/prometheus_exporter.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+
+namespace exporter
+{
+namespace prometheus
+{
+/**
+ * Constructor - binds an exposer and collector to the exporter
+ * @param address: an address for an exposer that exposes
+ * an HTTP endpoint for the exporter to connect to
+ */
+PrometheusExporter::PrometheusExporter(std::string &address) : is_shutdown_(false)
+{
+ exposer_ = std::unique_ptr<::prometheus::Exposer>(new ::prometheus::Exposer{address});
+ collector_ = std::shared_ptr<PrometheusCollector>(new PrometheusCollector);
+
+ exposer_->RegisterCollectable(collector_);
+}
+
+/**
+ * PrometheusExporter constructor with no parameters
+ * Used for testing only
+ */
+PrometheusExporter::PrometheusExporter() : is_shutdown_(false)
+{
+ collector_ = std::unique_ptr<PrometheusCollector>(new PrometheusCollector);
+}
+
+/**
+ * Exports a batch of Metric Records.
+ * @param records: a collection of records to export
+ * @return: returns a ReturnCode detailing a success, or type of failure
+ */
+sdk::common::ExportResult PrometheusExporter::Export(
+ const std::vector<sdk::metrics::Record> &records) noexcept
+{
+ if (is_shutdown_)
+ {
+ return sdk::common::ExportResult::kFailure;
+ }
+ else if (records.empty())
+ {
+ return sdk::common::ExportResult::kFailureInvalidArgument;
+ }
+ else if (collector_->GetCollection().size() + records.size() >
+ (size_t)collector_->GetMaxCollectionSize())
+ {
+ return sdk::common::ExportResult::kFailureFull;
+ }
+ else
+ {
+ collector_->AddMetricData(records);
+ return sdk::common::ExportResult::kSuccess;
+ }
+}
+
+/**
+ * Shuts down the exporter and does cleanup.
+ * Since Prometheus is a pull based interface,
+ * we cannot serve data remaining in the intermediate
+ * collection to to client an HTTP request being sent,
+ * so we flush the data.
+ */
+void PrometheusExporter::Shutdown() noexcept
+{
+ is_shutdown_ = true;
+
+ collector_->GetCollection().clear();
+}
+
+/**
+ * @return: returns a shared_ptr to
+ * the PrometheusCollector instance
+ */
+std::shared_ptr<PrometheusCollector> &PrometheusExporter::GetCollector()
+{
+ return collector_;
+}
+
+/**
+ * @return: Gets the shutdown status of the exporter
+ */
+bool PrometheusExporter::IsShutdown() const
+{
+ return is_shutdown_;
+}
+
+} // namespace prometheus
+} // namespace exporter
+OPENTELEMETRY_END_NAMESPACE
+#endif // ENABLE_METRICS_PREVIEW

exporters/prometheus/test/CMakeLists.txt

@@ -1,4 +1,5 @@
-foreach(testname prometheus_collector_test prometheus_exporter_utils_test)
+foreach(testname prometheus_exporter_test prometheus_collector_test
+ prometheus_exporter_utils_test)
  add_executable(${testname} "${testname}.cc")
  target_link_libraries(
  ${testname} ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT}