examples: Add gRPC OpenTelemetry example (#11299)

Add gRPC OpenTelemetry example. The example uses Prometheus exporter to export metrics and can be verified locally.
It also provides an example using LoggingMetricExporter to export and log the metrics using java.util.logging.

examples/example-opentelemetry/README.md

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+gRPC OpenTelemetry Example
+================
+
+The example extends the gRPC "hello world" example by modifying the client and server to
+showcase a sample configuration for gRPC OpenTelemetry with a Prometheus exporter.
+
+The example requires grpc-java to be pre-built. Using a release tag will download the relevant binaries
+from a maven repository. But if you need the latest SNAPSHOT binaries you will need to follow
+[COMPILING](../../COMPILING.md) to build these.
+
+### Build the example
+
+The source code is [here](src/main/java/io/grpc/examples/opentelemetry).
+To build the example, run in this directory:
+```
+$ ../gradlew installDist
+```
+The build creates scripts `opentelemetry-server` and `opentelemetry-client` in the `build/install/example-opentelemetry/bin/` directory
+which can be used to run this example. The example requires the server to be running before starting the
+client.
+
+### Run the example
+
+**opentelemetry-server**:
+
+The opentelemetry-server accepts optional arguments for server-port and prometheus-port:
+
+```text
+USAGE: opentelemetry-server [server-port [prometheus-port]]
+```
+
+**opentelemetry-client**:
+
+The opentelemetry-client accepts optional arguments for user-name, target and prometheus-port:
+
+```text
+USAGE: opentelemetry-client-client [user-name [target [prometheus-port]]]
+```
+
+The opentelemetry-client continuously sends an RPC to the server every second.
+
+To make sure that the server and client metrics are being exported properly, in
+a separate terminal, run the following:
+
+```
+$ curl localhost:9464/metrics
+```
+
+```
+$ curl localhost:9465/metrics
+```
+
+> ***NOTE:*** If the prometheus endpoint configured is overridden, please update the target in the
+> above curl command.

examples/example-opentelemetry/build.gradle

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+plugins {
+    // Provide convenience executables for trying out the examples.
+    id 'application'
+    id 'com.google.protobuf' version '0.9.4'
+    // Generate IntelliJ IDEA's .idea & .iml project files
+    id 'idea'
+}
+
+repositories {
+    maven { // The google mirror is less flaky than mavenCentral()
+        url "https://maven-central.storage-download.googleapis.com/maven2/"
+    }
+    mavenCentral()
+    mavenLocal()
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}
+
+// IMPORTANT: You probably want the non-SNAPSHOT version of gRPC. Make sure you
+// are looking at a tagged version of the example and not "master"!
+
+// Feel free to delete the comment at the next line. It is just for safely
+// updating the version in our release process.
+def grpcVersion = '1.66.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def protocVersion = '3.25.1'
+def openTelemetryVersion = '1.39.0'
+def openTelemetryPrometheusVersion = '1.39.0-alpha'
+
+dependencies {
+    implementation "io.grpc:grpc-protobuf:${grpcVersion}"
+    implementation "io.grpc:grpc-stub:${grpcVersion}"
+    implementation "io.grpc:grpc-opentelemetry:${grpcVersion}"
+    implementation "io.opentelemetry:opentelemetry-sdk:${openTelemetryVersion}"
+    implementation "io.opentelemetry:opentelemetry-sdk-metrics:${openTelemetryVersion}"
+    implementation "io.opentelemetry:opentelemetry-exporter-logging:${openTelemetryVersion}"
+    implementation "io.opentelemetry:opentelemetry-exporter-prometheus:${openTelemetryPrometheusVersion}"
+    compileOnly "org.apache.tomcat:annotations-api:6.0.53"
+    runtimeOnly "io.grpc:grpc-netty-shaded:${grpcVersion}"
+}
+
+protobuf {
+    protoc { artifact = "com.google.protobuf:protoc:${protocVersion}" }
+    plugins {
+        grpc { artifact = "io.grpc:protoc-gen-grpc-java:${grpcVersion}" }
+    }
+    generateProtoTasks {
+        all()*.plugins { grpc {} }
+    }
+}
+
+startScripts.enabled = false
+
+task OpenTelemetryHelloWorldServer(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.opentelemetry.OpenTelemetryServer'
+    applicationName = 'opentelemetry-server'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+task OpenTelemetryHelloWorldClient(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.opentelemetry.OpenTelemetryClient'
+    applicationName = 'opentelemetry-client'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+task LoggingOpenTelemetryHelloWorldServer(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.opentelemetry.logging.LoggingOpenTelemetryServer'
+    applicationName = 'logging-opentelemetry-server'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+task LoggingOpenTelemetryHelloWorldClient(type: CreateStartScripts) {
+    mainClass = 'io.grpc.examples.opentelemetry.logging.LoggingOpenTelemetryClient'
+    applicationName = 'logging-opentelemetry-client'
+    outputDir = new File(project.buildDir, 'tmp/scripts/' + name)
+    classpath = startScripts.classpath
+}
+
+application {
+    applicationDistribution.into('bin') {
+        from(OpenTelemetryHelloWorldServer)
+        from(OpenTelemetryHelloWorldClient)
+        from(LoggingOpenTelemetryHelloWorldServer)
+        from(LoggingOpenTelemetryHelloWorldClient)
+        fileMode = 0755
+    }
+}

examples/example-opentelemetry/settings.gradle

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+rootProject.name = 'example-opentelemetry'

examples/example-opentelemetry/src/main/java/io/grpc/example/opentelemetry/OpenTelemetryClient.java

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+/*
+ * Copyright 2024 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.
+ */
+
+package io.grpc.examples.opentelemetry;
+
+import io.grpc.Channel;
+import io.grpc.Grpc;
+import io.grpc.InsecureChannelCredentials;
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.StatusRuntimeException;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.opentelemetry.GrpcOpenTelemetry;
+import io.opentelemetry.exporter.prometheus.PrometheusHttpServer;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * A simple gRPC client that requests a greeting from the {@link HelloWorldServer} and
+ * generates gRPC OpenTelmetry metrics data based on the configuration.
+ */
+public class OpenTelemetryClient {
+  private static final Logger logger = Logger.getLogger(OpenTelemetryClient.class.getName());
+
+  private final GreeterGrpc.GreeterBlockingStub blockingStub;
+
+  /** Construct client for accessing HelloWorld server using the existing channel. */
+  public OpenTelemetryClient(Channel channel) {
+    blockingStub = GreeterGrpc.newBlockingStub(channel);
+  }
+
+  /** Say hello to server. */
+  public void greet(String name) {
+    logger.info("Will try to greet " + name + " ...");
+    HelloRequest request = HelloRequest.newBuilder().setName(name).build();
+    HelloReply response;
+    try {
+      response = blockingStub.sayHello(request);
+    } catch (StatusRuntimeException e) {
+      logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
+      return;
+    }
+    logger.info("Greeting: " + response.getMessage());
+  }
+
+  /**
+   * Greet server. If provided, the first element of {@code args} is the name to use in the
+   * greeting. The second argument is the target server.
+   */
+  public static void main(String[] args) throws Exception {
+    String user = "world";
+    // Access a service running on the local machine on port 50051
+    String target = "localhost:50051";
+    // The port on which prometheus metrics are exposed.
+    int prometheusPort = 9465;
+    AtomicBoolean sendRpcs = new AtomicBoolean(true);
+    if (args.length > 0) {
+      if ("--help".equals(args[0])) {
+        System.err.println("Usage: [name [target [prometheusPort]]]");
+        System.err.println("");
+        System.err.println("  name    The name you wish to be greeted by. Defaults to " + user);
+        System.err.println("  target  The server to connect to. Defaults to " + target);
+        System.err.println("  prometheusPort  The port to expose prometheus metrics. Defaults to " + prometheusPort);
+        System.exit(1);
+      }
+      user = args[0];
+    }
+    if (args.length > 1) {
+      target = args[1];
+    }
+    if (args.length > 2) {
+      prometheusPort = Integer.parseInt(args[2]);
+    }
+
+    Thread mainThread = Thread.currentThread();
+
+    Runtime.getRuntime().addShutdownHook(new Thread() {
+      @Override
+      public void run() {
+        // Use stderr here since the logger may have been reset by its JVM shutdown hook.
+        System.err.println("*** shutting down gRPC client since JVM is shutting down");
+
+        sendRpcs.set(false);
+        try {
+          mainThread.join();
+        } catch (InterruptedException e) {
+          e.printStackTrace(System.err);
+        }
+        System.err.println("*** client shut down");
+      }
+    });
+
+    // Adds a PrometheusHttpServer to convert OpenTelemetry metrics to Prometheus format and
+    // expose these via a HttpServer exporter to the SdkMeterProvider.
+    SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
+        .registerMetricReader(
+            PrometheusHttpServer.builder().setPort(prometheusPort).build())
+        .build();
+
+    // Initialize OpenTelemetry SDK with MeterProvider configured with Prometeheus.
+    OpenTelemetrySdk openTelemetrySdk =
+        OpenTelemetrySdk.builder().setMeterProvider(sdkMeterProvider).build();
+
+    // Initialize gRPC OpenTelemetry.
+    // Following client metrics are enabled by default :
+    //     1. grpc.client.attempt.started
+    //     2. grpc.client.attempt.sent_total_compressed_message_size
+    //     3. grpc.client.attempt.rcvd_total_compressed_message_size
+    //     4. grpc.client.attempt.duration
+    //     5. grpc.client.call.duration
+    GrpcOpenTelemetry grpcOpenTelmetry = GrpcOpenTelemetry.newBuilder()
+        .sdk(openTelemetrySdk)
+        .build();
+    // Registers gRPC OpenTelemetry globally.
+    grpcOpenTelmetry.registerGlobal();
+
+    // Create a communication channel to the server, known as a Channel.
+    ManagedChannel channel = Grpc.newChannelBuilder(target, InsecureChannelCredentials.create())
+        .build();
+    OpenTelemetryClient client = new OpenTelemetryClient(channel);
+
+    try {
+      // Run RPCs every second.
+      while (sendRpcs.get()) {
+        client.greet(user);
+        // Sleep for a bit before sending the next RPC.
+        Thread.sleep(1000);
+      }
+    } finally {
+      channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+      // Shut down OpenTelemetry SDK.
+      openTelemetrySdk.close();
+    }
+  }
+}

examples/example-opentelemetry/src/main/java/io/grpc/example/opentelemetry/OpenTelemetryServer.java

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+/*
+ * Copyright 2024 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.
+ */
+
+package io.grpc.examples.opentelemetry;
+
+import io.grpc.Grpc;
+import io.grpc.InsecureServerCredentials;
+import io.grpc.Server;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.opentelemetry.GrpcOpenTelemetry;
+import io.grpc.stub.StreamObserver;
+import io.opentelemetry.exporter.prometheus.PrometheusHttpServer;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Logger;
+
+/**
+ * gRPC server that manages startup/shutdown of a {@code Greeter} server and generates
+ * gRPC OpenTelemetry metrics data based on the configuration.
+ */
+public class OpenTelemetryServer {
+  private static final Logger logger = Logger.getLogger(OpenTelemetryServer.class.getName());
+
+  private Server server;
+  private void start(int port) throws IOException {
+    server = Grpc.newServerBuilderForPort(port, InsecureServerCredentials.create())
+        .addService(new GreeterImpl())
+        .build()
+        .start();
+    logger.info("Server started, listening on " + port);
+  }
+
+  private void stop() throws InterruptedException {
+    if (server != null) {
+      server.shutdown().awaitTermination(30, TimeUnit.SECONDS);
+    }
+  }
+
+  /**
+   * Await termination on the main thread since the grpc library uses daemon threads.
+   */
+  private void blockUntilShutdown() throws InterruptedException {
+    if (server != null) {
+      server.awaitTermination();
+    }
+  }
+
+  /**
+   * Main launches the server from the command line.
+   */
+  public static void main(String[] args) throws IOException, InterruptedException {
+    // The port on which the server should run.
+    int port = 50051;
+    // The port on which prometheus metrics are exposed.
+    int prometheusPort = 9464;
+
+    if (args.length > 0) {
+      if ("--help".equals(args[0])) {
+        System.err.println("Usage: [port [prometheus_port]]");
+        System.err.println("");
+        System.err.println("  port  The port on which server will run. Defaults to " + port);
+        System.err.println("  prometheusPort  The port to expose prometheus metrics. Defaults to " + prometheusPort);
+        System.exit(1);
+      }
+      port = Integer.parseInt(args[0]);
+    }
+    if (args.length > 1) {
+      prometheusPort = Integer.parseInt(args[1]);
+    }
+
+    // Adds a PrometheusHttpServer to convert OpenTelemetry metrics to Prometheus format and
+    // expose these via a HttpServer exporter to the SdkMeterProvider.
+    SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
+        .registerMetricReader(
+            PrometheusHttpServer.builder().setPort(prometheusPort).build())
+        .build();
+
+    // Initialize OpenTelemetry SDK with MeterProvider configured with Prometheus metrics exporter
+    OpenTelemetrySdk openTelemetrySdk =
+        OpenTelemetrySdk.builder().setMeterProvider(sdkMeterProvider).build();
+
+    // Initialize gRPC OpenTelemetry.
+    // Following client metrics are enabled by default :
+    //     1. grpc.server.call.started
+    //     2. grpc.server.call.sent_total_compressed_message_size
+    //     3. grpc.server.call.rcvd_total_compressed_message_size
+    //     4. grpc.server.call.duration
+    GrpcOpenTelemetry grpcOpenTelmetry = GrpcOpenTelemetry.newBuilder()
+        .sdk(openTelemetrySdk)
+        .build();
+    // Registers gRPC OpenTelemetry globally.
+    grpcOpenTelmetry.registerGlobal();
+
+    final OpenTelemetryServer server = new OpenTelemetryServer();
+    server.start(port);
+
+    Runtime.getRuntime().addShutdownHook(new Thread() {
+      @Override
+      public void run() {
+        System.err.println("*** shutting down gRPC server since JVM is shutting down");
+        try {
+          server.stop();
+        } catch (InterruptedException e) {
+          e.printStackTrace(System.err);
+        }
+        // Shut down OpenTelemetry SDK.
+        openTelemetrySdk.close();
+
+        System.err.println("*** server shut down");
+      }
+    });
+
+    server.blockUntilShutdown();
+  }
+
+  static class GreeterImpl extends GreeterGrpc.GreeterImplBase {
+
+    @Override
+    public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
+      HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
+      responseObserver.onNext(reply);
+      responseObserver.onCompleted();
+    }
+  }
+}

examples/example-opentelemetry/src/main/java/io/grpc/example/opentelemetry/logging/LoggingOpenTelemetryClient.java

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+/*
+ * Copyright 2024 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.
+ */
+
+package io.grpc.examples.opentelemetry.logging;
+
+import io.grpc.Channel;
+import io.grpc.Grpc;
+import io.grpc.InsecureChannelCredentials;
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.StatusRuntimeException;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.opentelemetry.GrpcOpenTelemetry;
+import io.opentelemetry.exporter.logging.LoggingMetricExporter;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.export.PeriodicMetricReader;
+import java.time.Duration;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * A simple gRPC client that requests a greeting from the {@link HelloWorldServer} and
+ * exports gRPC OpenTelmetry metrics data using {@code java.util.logging}.
+ */
+public class LoggingOpenTelemetryClient {
+  private static final Logger logger = Logger.getLogger(LoggingOpenTelemetryClient.class.getName());
+
+  private final GreeterGrpc.GreeterBlockingStub blockingStub;
+
+  /** Construct client for accessing HelloWorld server using the existing channel. */
+  public LoggingOpenTelemetryClient(Channel channel) {
+    blockingStub = GreeterGrpc.newBlockingStub(channel);
+  }
+
+  /** Say hello to server. */
+  public void greet(String name) {
+    logger.info("Will try to greet " + name + " ...");
+    HelloRequest request = HelloRequest.newBuilder().setName(name).build();
+    HelloReply response;
+    try {
+      response = blockingStub.sayHello(request);
+    } catch (StatusRuntimeException e) {
+      logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
+      return;
+    }
+    logger.info("Greeting: " + response.getMessage());
+  }
+
+  /**
+   * Greet server. If provided, the first element of {@code args} is the name to use in the
+   * greeting. The second argument is the target server.
+   */
+  public static void main(String[] args) throws Exception {
+    String user = "world";
+    // Access a service running on the local machine on port 50051
+    String target = "localhost:50051";
+    // The number of milliseconds between metric exports.
+    long metricExportInterval = 800L;
+    AtomicBoolean sendRpcs = new AtomicBoolean(true);
+    if (args.length > 0) {
+      if ("--help".equals(args[0])) {
+        System.err.println("Usage: [name [target]]");
+        System.err.println("");
+        System.err.println("  name    The name you wish to be greeted by. Defaults to " + user);
+        System.err.println("  target  The server to connect to. Defaults to " + target);
+        System.exit(1);
+      }
+      user = args[0];
+    }
+    if (args.length > 1) {
+      target = args[1];
+    }
+
+    Thread mainThread = Thread.currentThread();
+
+    Runtime.getRuntime().addShutdownHook(new Thread() {
+      @Override
+      public void run() {
+        // Use stderr here since the logger may have been reset by its JVM shutdown hook.
+        System.err.println("*** shutting down gRPC client since JVM is shutting down");
+
+        sendRpcs.set(false);
+        try {
+          mainThread.join();
+        } catch (InterruptedException e) {
+          e.printStackTrace(System.err);
+        }
+        System.err.println("*** client shut down");
+      }
+    });
+
+    // Create an instance of PeriodicMetricReader and configure it to export
+    // via a logging exporter to the SdkMeterProvider.
+    SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
+        .registerMetricReader(
+            PeriodicMetricReader.builder(LoggingMetricExporter.create())
+                .setInterval(Duration.ofMillis(metricExportInterval))
+                .build())
+        .build();
+
+    // Initialize OpenTelemetry SDK with MeterProvider configured with Prometeheus.
+    OpenTelemetrySdk openTelemetrySdk =
+        OpenTelemetrySdk.builder().setMeterProvider(sdkMeterProvider).build();
+
+    // Initialize gRPC OpenTelemetry.
+    // Following client metrics are enabled by default :
+    //     1. grpc.client.attempt.started
+    //     2. grpc.client.attempt.sent_total_compressed_message_size
+    //     3. grpc.client.attempt.rcvd_total_compressed_message_size
+    //     4. grpc.client.attempt.duration
+    //     5. grpc.client.call.duration
+    GrpcOpenTelemetry grpcOpenTelmetry = GrpcOpenTelemetry.newBuilder()
+        .sdk(openTelemetrySdk)
+        .build();
+    // Registers gRPC OpenTelemetry globally.
+    grpcOpenTelmetry.registerGlobal();
+
+    // Create a communication channel to the server, known as a Channel.
+    ManagedChannel channel = Grpc.newChannelBuilder(target, InsecureChannelCredentials.create())
+        .build();
+    LoggingOpenTelemetryClient client = new LoggingOpenTelemetryClient(channel);
+
+    try {
+      // Run RPCs every second.
+      while (sendRpcs.get()) {
+        client.greet(user);
+        // Sleep for a bit before sending the next RPC.
+        Thread.sleep(1000);
+      }
+    } finally {
+      channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
+      // Shut down OpenTelemetry SDK.
+      openTelemetrySdk.close();
+    }
+  }
+}

examples/example-opentelemetry/src/main/java/io/grpc/example/opentelemetry/logging/LoggingOpenTelemetryServer.java

@@ -0,0 +1,144 @@
+/*
+ * Copyright 2024 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.
+ */
+
+package io.grpc.examples.opentelemetry.logging;
+
+import io.grpc.Grpc;
+import io.grpc.InsecureServerCredentials;
+import io.grpc.Server;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.opentelemetry.GrpcOpenTelemetry;
+import io.grpc.stub.StreamObserver;
+import io.opentelemetry.exporter.logging.LoggingMetricExporter;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.metrics.SdkMeterProvider;
+import io.opentelemetry.sdk.metrics.export.PeriodicMetricReader;
+import java.time.Duration;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.logging.Logger;
+
+/**
+ * gRPC server that manages startup/shutdown of a {@code Greeter} server and exports
+ * gRPC OpenTelemetry metrics data using {@code java.util.logging}.
+ */
+public class LoggingOpenTelemetryServer {
+  private static final Logger logger = Logger.getLogger(LoggingOpenTelemetryServer.class.getName());
+
+  private Server gRPCServer;
+  private void start(int port) throws IOException {
+    gRPCServer = Grpc.newServerBuilderForPort(port, InsecureServerCredentials.create())
+        .addService(new GreeterImpl())
+        .build()
+        .start();
+    logger.info("Server started, listening on " + port);
+  }
+
+  private void stop() throws InterruptedException {
+    if (gRPCServer != null) {
+      gRPCServer.shutdown().awaitTermination(30, TimeUnit.SECONDS);
+    }
+  }
+
+  /**
+   * Await termination on the main thread since the grpc library uses daemon threads.
+   */
+  private void blockUntilShutdown() throws InterruptedException {
+    if (gRPCServer != null) {
+      gRPCServer.awaitTermination();
+    }
+  }
+
+  /**
+   * Main launches the server from the command line.
+   */
+  public static void main(String[] args) throws IOException, InterruptedException {
+    // The port on which the server should run.
+    int port = 50051;
+    // The port on which prometheus metrics are exposed.
+    int prometheusPort = 9464;
+    // The number of milliseconds between metric exports.
+    long metricExportInterval = 800L;
+
+    if (args.length > 0) {
+      if ("--help".equals(args[0])) {
+        System.err.println("Usage: [port]");
+        System.err.println("");
+        System.err.println("  port  The port on which server will run. Defaults to " + port);
+        System.exit(1);
+      }
+      port = Integer.parseInt(args[0]);
+    }
+
+    // Create an instance of PeriodicMetricReader and configure it to export
+    // via a logging exporter to the SdkMeterProvider.
+    SdkMeterProvider sdkMeterProvider = SdkMeterProvider.builder()
+        .registerMetricReader(
+            PeriodicMetricReader.builder(LoggingMetricExporter.create())
+                .setInterval(Duration.ofMillis(metricExportInterval))
+                .build())
+        .build();
+
+    // Initialize OpenTelemetry SDK with MeterProvider configured with Logging metrics exporter
+    OpenTelemetrySdk openTelemetrySdk =
+        OpenTelemetrySdk.builder().setMeterProvider(sdkMeterProvider).build();
+
+    // Initialize gRPC OpenTelemetry.
+    // Following client metrics are enabled by default :
+    //     1. grpc.server.call.started
+    //     2. grpc.server.call.sent_total_compressed_message_size
+    //     3. grpc.server.call.rcvd_total_compressed_message_size
+    //     4. grpc.server.call.duration
+    GrpcOpenTelemetry grpcOpenTelmetry = GrpcOpenTelemetry.newBuilder()
+        .sdk(openTelemetrySdk)
+        .build();
+    // Registers gRPC OpenTelemetry globally.
+    grpcOpenTelmetry.registerGlobal();
+
+    final LoggingOpenTelemetryServer server = new LoggingOpenTelemetryServer();
+    server.start(port);
+
+    Runtime.getRuntime().addShutdownHook(new Thread() {
+      @Override
+      public void run() {
+        System.err.println("*** shutting down gRPC server since JVM is shutting down");
+        try {
+          server.stop();
+        } catch (InterruptedException e) {
+          e.printStackTrace(System.err);
+        }
+        // Shut down OpenTelemetry SDK.
+        openTelemetrySdk.close();
+
+        System.err.println("*** server shut down");
+      }
+    });
+
+    server.blockUntilShutdown();
+  }
+
+  static class GreeterImpl extends GreeterGrpc.GreeterImplBase {
+
+    @Override
+    public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
+      HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
+      responseObserver.onNext(reply);
+      responseObserver.onCompleted();
+    }
+  }
+}

examples/example-opentelemetry/src/main/proto/helloworld/helloworld.proto

@@ -0,0 +1,39 @@
+/*
+ * 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.
+ */
+syntax = "proto3";
+
+option java_multiple_files = true;
+option java_package = "io.grpc.examples.helloworld";
+option java_outer_classname = "HelloWorldProto";
+option objc_class_prefix = "HLW";
+
+package helloworld;
+
+// The greeting service definition.
+service Greeter {
+  // Sends a greeting
+  rpc SayHello (HelloRequest) returns (HelloReply) {}
+}
+
+// The request message containing the user's name.
+message HelloRequest {
+  string name = 1;
+}
+
+// The response message containing the greetings
+message HelloReply {
+  string message = 1;
+}