[codelab] Add a codelab for gRPC C++ OTel plugin (#37318)

Closes #37318

PiperOrigin-RevId: 658586660

examples/cpp/otel/codelab/BUILD

@@ -0,0 +1,99 @@
+# Copyright 2023 the gRPC 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.
+
+licenses(["notice"])
+
+package(
+    default_visibility = ["//examples/cpp:__subpackages__"],
+)
+
+cc_library(
+    name = "util",
+    srcs = ["util.cc"],
+    hdrs = ["util.h"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "//:grpc++",
+        "//examples/protos:helloworld_cc_grpc",
+        "@io_opentelemetry_cpp//sdk/src/metrics",
+    ],
+)
+
+cc_binary(
+    name = "greeter_callback_client",
+    srcs = ["greeter_callback_client.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "util",
+        "//:grpc++",
+        "//:grpcpp_otel_plugin",
+        "//examples/cpp/otel:util",
+        "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:parse",
+        "@io_opentelemetry_cpp//exporters/prometheus:prometheus_exporter",
+        "@io_opentelemetry_cpp//sdk/src/metrics",
+    ],
+)
+
+cc_binary(
+    name = "greeter_callback_server",
+    srcs = ["greeter_callback_server.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "util",
+        "//:grpc++",
+        "//:grpc++_reflection",
+        "//:grpcpp_otel_plugin",
+        "//examples/cpp/otel:util",
+        "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:parse",
+        "@com_google_absl//absl/strings:str_format",
+        "@io_opentelemetry_cpp//exporters/prometheus:prometheus_exporter",
+        "@io_opentelemetry_cpp//sdk/src/metrics",
+    ],
+)
+
+cc_binary(
+    name = "greeter_callback_client_solution",
+    srcs = ["greeter_callback_client_solution.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "util",
+        "//:grpc++",
+        "//:grpcpp_otel_plugin",
+        "//examples/cpp/otel:util",
+        "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:parse",
+        "@io_opentelemetry_cpp//exporters/prometheus:prometheus_exporter",
+        "@io_opentelemetry_cpp//sdk/src/metrics",
+    ],
+)
+
+cc_binary(
+    name = "greeter_callback_server_solution",
+    srcs = ["greeter_callback_server_solution.cc"],
+    defines = ["BAZEL_BUILD"],
+    deps = [
+        "util",
+        "//:grpc++",
+        "//:grpc++_reflection",
+        "//:grpcpp_otel_plugin",
+        "//examples/cpp/otel:util",
+        "@com_google_absl//absl/flags:flag",
+        "@com_google_absl//absl/flags:parse",
+        "@com_google_absl//absl/strings:str_format",
+        "@io_opentelemetry_cpp//exporters/prometheus:prometheus_exporter",
+        "@io_opentelemetry_cpp//sdk/src/metrics",
+    ],
+)

examples/cpp/otel/codelab/CMakeLists.txt

@@ -0,0 +1,87 @@
+# Copyright 2018 gRPC 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.
+#
+# cmake build file for C++ gRPC OpenTelemetry example.
+# Assumes absl, protobuf, prometheus-cpp, opentelemetry-cpp and gRPC (with -DgRPC_BUILD_OPENTELEMETRY_PLUGIN=ON) have been installed using cmake.
+# See cmake_externalproject/CMakeLists.txt for all-in-one cmake build
+# that automatically builds all the dependencies before building helloworld.
+
+cmake_minimum_required(VERSION 3.13)
+
+project(grpc_opentelemetry_example C CXX)
+
+include(../../cmake/common.cmake)
+
+# Find prometheus-cpp package
+find_package(prometheus-cpp CONFIG REQUIRED)
+
+# Find opentelemetry-cpp package
+find_package(opentelemetry-cpp CONFIG REQUIRED)
+
+# Proto file
+get_filename_component(hw_proto "../../../protos/helloworld.proto" ABSOLUTE)
+get_filename_component(hw_proto_path "${hw_proto}" PATH)
+
+# Generated sources
+set(hw_proto_srcs "${CMAKE_CURRENT_BINARY_DIR}/helloworld.pb.cc")
+set(hw_proto_hdrs "${CMAKE_CURRENT_BINARY_DIR}/helloworld.pb.h")
+set(hw_grpc_srcs "${CMAKE_CURRENT_BINARY_DIR}/helloworld.grpc.pb.cc")
+set(hw_grpc_hdrs "${CMAKE_CURRENT_BINARY_DIR}/helloworld.grpc.pb.h")
+add_custom_command(
+      OUTPUT "${hw_proto_srcs}" "${hw_proto_hdrs}" "${hw_grpc_srcs}" "${hw_grpc_hdrs}"
+      COMMAND ${_PROTOBUF_PROTOC}
+      ARGS --grpc_out "${CMAKE_CURRENT_BINARY_DIR}"
+        --cpp_out "${CMAKE_CURRENT_BINARY_DIR}"
+        -I "${hw_proto_path}"
+        --plugin=protoc-gen-grpc="${_GRPC_CPP_PLUGIN_EXECUTABLE}"
+        "${hw_proto}"
+      DEPENDS "${hw_proto}")
+
+# Include generated *.pb.h files
+include_directories("${CMAKE_CURRENT_BINARY_DIR}")
+include_directories("${CMAKE_SOURCE_DIR}")
+
+# hw_grpc_proto
+add_library(hw_grpc_proto
+  ${hw_grpc_srcs}
+  ${hw_grpc_hdrs}
+  ${hw_proto_srcs}
+  ${hw_proto_hdrs})
+target_link_libraries(hw_grpc_proto
+  ${_REFLECTION}
+  ${_GRPC_GRPCPP}
+  ${_PROTOBUF_LIBPROTOBUF})
+
+# util
+add_library(util
+  "util.cc")
+target_link_libraries(util
+  hw_grpc_proto
+  opentelemetry-cpp::metrics
+  ${_GRPC_GRPCPP}
+  ${_REFLECTION}
+  ${_PROTOBUF_LIBPROTOBUF})
+
+# Targets greeter_callback_(client|server) greeter_callback_(client|server)_solution
+foreach(_target
+  greeter_callback_client greeter_callback_server greeter_callback_client_solution greeter_callback_server_solution)
+  add_executable(${_target} "${_target}.cc")
+  target_link_libraries(${_target}
+    absl::flags
+    absl::flags_parse
+    opentelemetry-cpp::metrics
+    opentelemetry-cpp::prometheus_exporter
+    gRPC::grpcpp_otel_plugin
+    util)
+endforeach()

examples/cpp/otel/codelab/greeter_callback_client.cc

@@ -0,0 +1,138 @@
+/*
+ *
+ * Copyright 2021 gRPC 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.
+ *
+ */
+
+// Explicitly define HAVE_ABSEIL to avoid conflict with OTel's Abseil
+// version. Refer
+// https://github.com/open-telemetry/opentelemetry-cpp/issues/1042.
+#ifndef HAVE_ABSEIL
+#define HAVE_ABSEIL
+#endif
+
+#include <condition_variable>
+#include <mutex>
+#include <string>
+
+#include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
+#include "opentelemetry/exporters/prometheus/exporter_factory.h"
+#include "opentelemetry/exporters/prometheus/exporter_options.h"
+#include "opentelemetry/sdk/metrics/meter_provider.h"
+
+#include <grpcpp/ext/otel_plugin.h>
+#include <grpcpp/grpcpp.h>
+
+#ifdef BAZEL_BUILD
+#include "examples/cpp/otel/codelab/util.h"
+#include "examples/protos/helloworld.grpc.pb.h"
+#else
+#include "helloworld.grpc.pb.h"
+#include "util.h"
+#endif
+
+ABSL_FLAG(std::string, target, "localhost:50051", "Server address");
+ABSL_FLAG(std::string, prometheus_endpoint, "localhost:9465",
+          "Prometheus exporter endpoint");
+
+namespace {
+
+using grpc::Channel;
+using grpc::ClientContext;
+using grpc::Status;
+using helloworld::Greeter;
+using helloworld::HelloReply;
+using helloworld::HelloRequest;
+
+class GreeterClient {
+ public:
+  GreeterClient(std::shared_ptr<Channel> channel)
+      : stub_(Greeter::NewStub(channel)) {}
+
+  // Assembles the client's payload, sends it and presents the response back
+  // from the server.
+  std::string SayHello(const std::string& user) {
+    // Data we are sending to the server.
+    HelloRequest request;
+    request.set_name(user);
+
+    // Container for the data we expect from the server.
+    HelloReply reply;
+
+    // Context for the client. It could be used to convey extra information to
+    // the server and/or tweak certain RPC behaviors.
+    ClientContext context;
+
+    // The actual RPC.
+    std::mutex mu;
+    std::condition_variable cv;
+    bool done = false;
+    Status status;
+    stub_->async()->SayHello(&context, &request, &reply,
+                             [&mu, &cv, &done, &status](Status s) {
+                               status = std::move(s);
+                               std::lock_guard<std::mutex> lock(mu);
+                               done = true;
+                               cv.notify_one();
+                             });
+
+    std::unique_lock<std::mutex> lock(mu);
+    while (!done) {
+      cv.wait(lock);
+    }
+
+    // Act upon its status.
+    if (status.ok()) {
+      return reply.message();
+    } else {
+      std::cout << status.error_code() << ": " << status.error_message()
+                << std::endl;
+      return "RPC failed";
+    }
+  }
+
+ private:
+  std::unique_ptr<Greeter::Stub> stub_;
+};
+
+void RunClient(const std::string& target_str) {
+  // Instantiate the client. It requires a channel, out of which the actual RPCs
+  // are created. This channel models a connection to an endpoint specified by
+  // the argument "--target=" which is the only expected argument.
+  grpc::ChannelArguments args;
+  // Continuously send RPCs every second.
+  while (true) {
+    GreeterClient greeter(grpc::CreateCustomChannel(
+        target_str, grpc::InsecureChannelCredentials(), args));
+    std::string user("world");
+    std::string reply = greeter.SayHello(user);
+    std::cout << "Greeter received: " << reply << std::endl;
+    std::this_thread::sleep_for(std::chrono::seconds(1));
+  }
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
+
+  // CODELAB HINT : Add code to register gRPC OpenTelemetry plugin here.
+
+  // Continuously send RPCs.
+  RunClient(absl::GetFlag(FLAGS_target));
+
+  return 0;
+}

examples/cpp/otel/codelab/greeter_callback_client_solution.cc

@@ -0,0 +1,158 @@
+/*
+ *
+ * Copyright 2021 gRPC 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.
+ *
+ */
+
+// Explicitly define HAVE_ABSEIL to avoid conflict with OTel's Abseil
+// version. Refer
+// https://github.com/open-telemetry/opentelemetry-cpp/issues/1042.
+#ifndef HAVE_ABSEIL
+#define HAVE_ABSEIL
+#endif
+
+#include <condition_variable>
+#include <mutex>
+#include <string>
+
+#include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
+#include "opentelemetry/exporters/prometheus/exporter_factory.h"
+#include "opentelemetry/exporters/prometheus/exporter_options.h"
+#include "opentelemetry/sdk/metrics/meter_provider.h"
+
+#include <grpcpp/ext/otel_plugin.h>
+#include <grpcpp/grpcpp.h>
+
+#ifdef BAZEL_BUILD
+#include "examples/cpp/otel/codelab/util.h"
+#include "examples/protos/helloworld.grpc.pb.h"
+#else
+#include "helloworld.grpc.pb.h"
+#include "util.h"
+#endif
+
+ABSL_FLAG(std::string, target, "localhost:50051", "Server address");
+ABSL_FLAG(std::string, prometheus_endpoint, "localhost:9465",
+          "Prometheus exporter endpoint");
+
+namespace {
+
+using grpc::Channel;
+using grpc::ClientContext;
+using grpc::Status;
+using helloworld::Greeter;
+using helloworld::HelloReply;
+using helloworld::HelloRequest;
+
+class GreeterClient {
+ public:
+  GreeterClient(std::shared_ptr<Channel> channel)
+      : stub_(Greeter::NewStub(channel)) {}
+
+  // Assembles the client's payload, sends it and presents the response back
+  // from the server.
+  std::string SayHello(const std::string& user) {
+    // Data we are sending to the server.
+    HelloRequest request;
+    request.set_name(user);
+
+    // Container for the data we expect from the server.
+    HelloReply reply;
+
+    // Context for the client. It could be used to convey extra information to
+    // the server and/or tweak certain RPC behaviors.
+    ClientContext context;
+
+    // The actual RPC.
+    std::mutex mu;
+    std::condition_variable cv;
+    bool done = false;
+    Status status;
+    stub_->async()->SayHello(&context, &request, &reply,
+                             [&mu, &cv, &done, &status](Status s) {
+                               status = std::move(s);
+                               std::lock_guard<std::mutex> lock(mu);
+                               done = true;
+                               cv.notify_one();
+                             });
+
+    std::unique_lock<std::mutex> lock(mu);
+    while (!done) {
+      cv.wait(lock);
+    }
+
+    // Act upon its status.
+    if (status.ok()) {
+      return reply.message();
+    } else {
+      std::cout << status.error_code() << ": " << status.error_message()
+                << std::endl;
+      return "RPC failed";
+    }
+  }
+
+ private:
+  std::unique_ptr<Greeter::Stub> stub_;
+};
+
+void RunClient(const std::string& target_str) {
+  // Instantiate the client. It requires a channel, out of which the actual RPCs
+  // are created. This channel models a connection to an endpoint specified by
+  // the argument "--target=" which is the only expected argument.
+  grpc::ChannelArguments args;
+  // Continuously send RPCs every second.
+  while (true) {
+    GreeterClient greeter(grpc::CreateCustomChannel(
+        target_str, grpc::InsecureChannelCredentials(), args));
+    std::string user("world");
+    std::string reply = greeter.SayHello(user);
+    std::cout << "Greeter received: " << reply << std::endl;
+    std::this_thread::sleep_for(std::chrono::seconds(1));
+  }
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
+  // CODELAB HINT : Add code to register OpenTelemetry plugin here.
+  // Register a global gRPC OpenTelemetry plugin configured with a prometheus
+  // exporter.
+  opentelemetry::exporter::metrics::PrometheusExporterOptions opts;
+  opts.url = absl::GetFlag(FLAGS_prometheus_endpoint);
+  auto prometheus_exporter =
+      opentelemetry::exporter::metrics::PrometheusExporterFactory::Create(opts);
+  auto meter_provider =
+      std::make_shared<opentelemetry::sdk::metrics::MeterProvider>();
+  // The default histogram boundaries are not granular enough for RPCs. Override
+  // the "grpc.client.attempt.duration" view as recommended by
+  // https://github.com/grpc/proposal/blob/master/A66-otel-stats.md.
+  AddLatencyView(meter_provider.get(), "grpc.client.attempt.duration", "s");
+  meter_provider->AddMetricReader(std::move(prometheus_exporter));
+  auto status = grpc::OpenTelemetryPluginBuilder()
+                    .SetMeterProvider(std::move(meter_provider))
+                    .BuildAndRegisterGlobal();
+  if (!status.ok()) {
+    std::cerr << "Failed to register gRPC OpenTelemetry Plugin: "
+              << status.ToString() << std::endl;
+    return static_cast<int>(status.code());
+  }
+
+  // Continuously send RPCs.
+  RunClient(absl::GetFlag(FLAGS_target));
+
+  return 0;
+}

examples/cpp/otel/codelab/greeter_callback_server.cc

@@ -0,0 +1,112 @@
+/*
+ *
+ * Copyright 2021 gRPC 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.
+ *
+ */
+
+// Explicitly define HAVE_ABSEIL to avoid conflict with OTel's Abseil
+// version. Refer
+// https://github.com/open-telemetry/opentelemetry-cpp/issues/1042.
+#ifndef HAVE_ABSEIL
+#define HAVE_ABSEIL
+#endif
+
+#include <iostream>
+#include <memory>
+#include <string>
+
+#include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
+#include "absl/strings/str_format.h"
+#include "opentelemetry/exporters/prometheus/exporter_factory.h"
+#include "opentelemetry/exporters/prometheus/exporter_options.h"
+#include "opentelemetry/sdk/metrics/meter_provider.h"
+
+#include <grpcpp/ext/otel_plugin.h>
+#include <grpcpp/ext/proto_server_reflection_plugin.h>
+#include <grpcpp/grpcpp.h>
+#include <grpcpp/health_check_service_interface.h>
+
+#ifdef BAZEL_BUILD
+#include "examples/cpp/otel/codelab/util.h"
+#include "examples/protos/helloworld.grpc.pb.h"
+#else
+#include "helloworld.grpc.pb.h"
+#include "util.h"
+#endif
+
+ABSL_FLAG(uint16_t, port, 50051, "Server port for the service");
+ABSL_FLAG(std::string, prometheus_endpoint, "localhost:9464",
+          "Prometheus exporter endpoint");
+
+namespace {
+
+using grpc::CallbackServerContext;
+using grpc::Server;
+using grpc::ServerBuilder;
+using grpc::ServerUnaryReactor;
+using grpc::Status;
+using helloworld::Greeter;
+using helloworld::HelloReply;
+using helloworld::HelloRequest;
+
+// Logic and data behind the server's behavior.
+class GreeterServiceImpl final : public Greeter::CallbackService {
+  ServerUnaryReactor* SayHello(CallbackServerContext* context,
+                               const HelloRequest* request,
+                               HelloReply* reply) override {
+    std::string prefix("Hello ");
+    reply->set_message(prefix + request->name());
+
+    // CODELAB HINT: This sleep seems suspicious.
+    std::this_thread::sleep_for(std::chrono::seconds(5));
+
+    ServerUnaryReactor* reactor = context->DefaultReactor();
+    reactor->Finish(Status::OK);
+    return reactor;
+  }
+};
+
+void RunServer(uint16_t port) {
+  std::string server_address = absl::StrFormat("0.0.0.0:%d", port);
+  GreeterServiceImpl service;
+
+  grpc::EnableDefaultHealthCheckService(true);
+  grpc::reflection::InitProtoReflectionServerBuilderPlugin();
+  ServerBuilder builder;
+  // Listen on the given address without any authentication mechanism.
+  builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
+  // Register "service" as the instance through which we'll communicate with
+  // clients. In this case it corresponds to an *synchronous* service.
+  builder.RegisterService(&service);
+  // Finally assemble the server.
+  std::unique_ptr<Server> server(builder.BuildAndStart());
+  std::cout << "Server listening on " << server_address << std::endl;
+
+  // Wait for the server to shutdown. Note that some other thread must be
+  // responsible for shutting down the server for this call to ever return.
+  server->Wait();
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
+
+  // CODELAB HINT : Add code to register gRPC OpenTelemetry plugin here.
+
+  RunServer(absl::GetFlag(FLAGS_port));
+  return 0;
+}

examples/cpp/otel/codelab/greeter_callback_server_solution.cc

@@ -0,0 +1,127 @@
+/*
+ *
+ * Copyright 2021 gRPC 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.
+ *
+ */
+
+// Explicitly define HAVE_ABSEIL to avoid conflict with OTel's Abseil
+// version. Refer
+// https://github.com/open-telemetry/opentelemetry-cpp/issues/1042.
+#ifndef HAVE_ABSEIL
+#define HAVE_ABSEIL
+#endif
+
+#include <iostream>
+#include <memory>
+#include <string>
+
+#include "absl/flags/flag.h"
+#include "absl/flags/parse.h"
+#include "absl/strings/str_format.h"
+#include "opentelemetry/exporters/prometheus/exporter_factory.h"
+#include "opentelemetry/exporters/prometheus/exporter_options.h"
+#include "opentelemetry/sdk/metrics/meter_provider.h"
+
+#include <grpcpp/ext/otel_plugin.h>
+#include <grpcpp/ext/proto_server_reflection_plugin.h>
+#include <grpcpp/grpcpp.h>
+#include <grpcpp/health_check_service_interface.h>
+
+#ifdef BAZEL_BUILD
+#include "examples/cpp/otel/codelab/util.h"
+#include "examples/protos/helloworld.grpc.pb.h"
+#else
+#include "helloworld.grpc.pb.h"
+#include "util.h"
+#endif
+
+ABSL_FLAG(uint16_t, port, 50051, "Server port for the service");
+ABSL_FLAG(std::string, prometheus_endpoint, "localhost:9464",
+          "Prometheus exporter endpoint");
+
+namespace {
+
+using grpc::CallbackServerContext;
+using grpc::Server;
+using grpc::ServerBuilder;
+using grpc::ServerUnaryReactor;
+using grpc::Status;
+using helloworld::Greeter;
+using helloworld::HelloReply;
+using helloworld::HelloRequest;
+
+// Logic and data behind the server's behavior.
+class GreeterServiceImpl final : public Greeter::CallbackService {
+  ServerUnaryReactor* SayHello(CallbackServerContext* context,
+                               const HelloRequest* request,
+                               HelloReply* reply) override {
+    std::string prefix("Hello ");
+    reply->set_message(prefix + request->name());
+
+    ServerUnaryReactor* reactor = context->DefaultReactor();
+    reactor->Finish(Status::OK);
+    return reactor;
+  }
+};
+
+void RunServer(uint16_t port) {
+  std::string server_address = absl::StrFormat("0.0.0.0:%d", port);
+  GreeterServiceImpl service;
+
+  grpc::EnableDefaultHealthCheckService(true);
+  grpc::reflection::InitProtoReflectionServerBuilderPlugin();
+  ServerBuilder builder;
+  // Listen on the given address without any authentication mechanism.
+  builder.AddListeningPort(server_address, grpc::InsecureServerCredentials());
+  // Register "service" as the instance through which we'll communicate with
+  // clients. In this case it corresponds to an *synchronous* service.
+  builder.RegisterService(&service);
+  // Finally assemble the server.
+  std::unique_ptr<Server> server(builder.BuildAndStart());
+  std::cout << "Server listening on " << server_address << std::endl;
+
+  // Wait for the server to shutdown. Note that some other thread must be
+  // responsible for shutting down the server for this call to ever return.
+  server->Wait();
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+  absl::ParseCommandLine(argc, argv);
+  // Register a global gRPC OpenTelemetry plugin configured with a prometheus
+  // exporter.
+  opentelemetry::exporter::metrics::PrometheusExporterOptions opts;
+  opts.url = absl::GetFlag(FLAGS_prometheus_endpoint);
+  auto prometheus_exporter =
+      opentelemetry::exporter::metrics::PrometheusExporterFactory::Create(opts);
+  auto meter_provider =
+      std::make_shared<opentelemetry::sdk::metrics::MeterProvider>();
+  // The default histogram boundaries are not granular enough for RPCs. Override
+  // the "grpc.server.call.duration" view as recommended by
+  // https://github.com/grpc/proposal/blob/master/A66-otel-stats.md.
+  AddLatencyView(meter_provider.get(), "grpc.server.call.duration", "s");
+  meter_provider->AddMetricReader(std::move(prometheus_exporter));
+  auto status = grpc::OpenTelemetryPluginBuilder()
+                    .SetMeterProvider(std::move(meter_provider))
+                    .BuildAndRegisterGlobal();
+  if (!status.ok()) {
+    std::cerr << "Failed to register gRPC OpenTelemetry Plugin: "
+              << status.ToString() << std::endl;
+    return static_cast<int>(status.code());
+  }
+  RunServer(absl::GetFlag(FLAGS_port));
+  return 0;
+}

examples/cpp/otel/codelab/util.cc

@@ -0,0 +1,70 @@
+//
+//
+// Copyright 2024 gRPC 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.
+//
+//
+
+// Explicitly define HAVE_ABSEIL to avoid conflict with OTel's Abseil
+// version. Refer
+// https://github.com/open-telemetry/opentelemetry-cpp/issues/1042.
+#ifndef HAVE_ABSEIL
+#define HAVE_ABSEIL
+#endif
+
+#include "opentelemetry/sdk/metrics/view/instrument_selector_factory.h"
+#include "opentelemetry/sdk/metrics/view/meter_selector_factory.h"
+#include "opentelemetry/sdk/metrics/view/view_factory.h"
+
+#include <grpcpp/grpcpp.h>
+
+#ifdef BAZEL_BUILD
+#include "examples/cpp/otel/codelab/util.h"
+#include "examples/protos/helloworld.grpc.pb.h"
+#else
+#include "helloworld.grpc.pb.h"
+#include "util.h"
+#endif
+
+using grpc::CallbackServerContext;
+using grpc::Channel;
+using grpc::ClientContext;
+using grpc::Server;
+using grpc::ServerBuilder;
+using grpc::ServerUnaryReactor;
+using grpc::Status;
+using helloworld::Greeter;
+using helloworld::HelloReply;
+using helloworld::HelloRequest;
+
+void AddLatencyView(opentelemetry::sdk::metrics::MeterProvider* provider,
+                    const std::string& name, const std::string& unit) {
+  auto histogram_config = std::make_shared<
+      opentelemetry::sdk::metrics::HistogramAggregationConfig>();
+  histogram_config->boundaries_ = {
+      0,     0.00001, 0.00005, 0.0001, 0.0003, 0.0006, 0.0008, 0.001, 0.002,
+      0.003, 0.004,   0.005,   0.006,  0.008,  0.01,   0.013,  0.016, 0.02,
+      0.025, 0.03,    0.04,    0.05,   0.065,  0.08,   0.1,    0.13,  0.16,
+      0.2,   0.25,    0.3,     0.4,    0.5,    0.65,   0.8,    1,     2,
+      5,     10,      20,      50,     100};
+  provider->AddView(
+      opentelemetry::sdk::metrics::InstrumentSelectorFactory::Create(
+          opentelemetry::sdk::metrics::InstrumentType::kHistogram, name, unit),
+      opentelemetry::sdk::metrics::MeterSelectorFactory::Create(
+          "grpc-c++", grpc::Version(), ""),
+      opentelemetry::sdk::metrics::ViewFactory::Create(
+          name, "", unit,
+          opentelemetry::sdk::metrics::AggregationType::kHistogram,
+          std::move(histogram_config)));
+}

examples/cpp/otel/codelab/util.h

@@ -0,0 +1,31 @@
+//
+//
+// Copyright 2024 gRPC 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.
+//
+//
+
+#ifndef GRPCPP_EXAMPLES_CPP_OTEL_CODELAB_UTIL_H
+#define GRPCPP_EXAMPLES_CPP_OTEL_CODELAB_UTIL_H
+
+#include <string>
+
+#include "opentelemetry/sdk/metrics/meter_provider.h"
+
+// Helper function that adds view for gRPC latency instrument \a name with unit
+// \a unit with bucket boundaries that are more useful for RPCs.
+void AddLatencyView(opentelemetry::sdk::metrics::MeterProvider* provider,
+                    const std::string& name, const std::string& unit);
+
+#endif  // GRPCPP_EXAMPLES_CPP_OTEL_UTIL_H