docs: Add OpenTelemetry samples (googleapis#2208)

* docs: Add OpenTelemetry samples

* docs: Fix sample file naming

samples/snippets/src/main/java/pubsub/OpenTelemetryPublisherExample.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 pubsub;
+
+// [START pubsub_publish_otel_tracing]
+
+import com.google.api.core.ApiFuture;
+import com.google.cloud.opentelemetry.trace.TraceConfiguration;
+import com.google.cloud.opentelemetry.trace.TraceExporter;
+import com.google.cloud.pubsub.v1.Publisher;
+import com.google.protobuf.ByteString;
+import com.google.pubsub.v1.PubsubMessage;
+import com.google.pubsub.v1.TopicName;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import io.opentelemetry.sdk.trace.samplers.Sampler;
+import io.opentelemetry.semconv.ResourceAttributes;
+import java.io.IOException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+public class OpenTelemetryPublisherExample {
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "your-project-id";
+    String topicId = "your-topic-id";
+
+    openTelemetryPublisherExample(projectId, topicId);
+  }
+
+  public static void openTelemetryPublisherExample(String projectId, String topicId)
+      throws IOException, ExecutionException, InterruptedException {
+    Resource resource =
+        Resource.getDefault().toBuilder()
+            .put(ResourceAttributes.SERVICE_NAME, "publisher-example")
+            .build();
+
+    // Creates a Cloud Trace exporter.
+    SpanExporter traceExporter =
+        TraceExporter.createWithConfiguration(
+            TraceConfiguration.builder().setProjectId(projectId).build());
+
+    SdkTracerProvider sdkTracerProvider =
+        SdkTracerProvider.builder()
+            .setResource(resource)
+            .addSpanProcessor(SimpleSpanProcessor.create(traceExporter))
+            .setSampler(Sampler.alwaysOn())
+            .build();
+
+    OpenTelemetry openTelemetry =
+        OpenTelemetrySdk.builder().setTracerProvider(sdkTracerProvider).buildAndRegisterGlobal();
+
+    TopicName topicName = TopicName.of(projectId, topicId);
+
+    Publisher publisher = null;
+    try {
+      // Create a publisher instance with the created OpenTelemetry object and enabling tracing.
+      publisher =
+          Publisher.newBuilder(topicName)
+              .setOpenTelemetry(openTelemetry)
+              .setEnableOpenTelemetryTracing(true)
+              .build();
+
+      String message = "Hello World!";
+      ByteString data = ByteString.copyFromUtf8(message);
+      PubsubMessage pubsubMessage = PubsubMessage.newBuilder().setData(data).build();
+
+      // Once published, returns a server-assigned message id (unique within the topic)
+      ApiFuture<String> messageIdFuture = publisher.publish(pubsubMessage);
+      String messageId = messageIdFuture.get();
+      System.out.println("Published message ID: " + messageId);
+    } finally {
+      if (publisher != null) {
+        // When finished with the publisher, shutdown to free up resources.
+        publisher.shutdown();
+        publisher.awaitTermination(1, TimeUnit.MINUTES);
+      }
+    }
+  }
+}
+// [END pubsub_publish_otel_tracing]

samples/snippets/src/main/java/pubsub/OpenTelemetrySubscriberExample.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * 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 pubsub;
+
+// [START pubsub_subscribe_otel_tracing]
+
+import com.google.cloud.opentelemetry.trace.TraceConfiguration;
+import com.google.cloud.opentelemetry.trace.TraceExporter;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.MessageReceiver;
+import com.google.cloud.pubsub.v1.Subscriber;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.PubsubMessage;
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.resources.Resource;
+import io.opentelemetry.sdk.trace.SdkTracerProvider;
+import io.opentelemetry.sdk.trace.export.SimpleSpanProcessor;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import io.opentelemetry.sdk.trace.samplers.Sampler;
+import io.opentelemetry.semconv.ResourceAttributes;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+public class OpenTelemetrySubscriberExample {
+  public static void main(String... args) throws Exception {
+    // TODO(developer): Replace these variables before running the sample.
+    String projectId = "your-project-id";
+    String subscriptionId = "your-subscription-id";
+
+    openTelemetrySubscriberExample(projectId, subscriptionId);
+  }
+
+  public static void openTelemetrySubscriberExample(String projectId, String subscriptionId) {
+    Resource resource =
+        Resource.getDefault().toBuilder()
+            .put(ResourceAttributes.SERVICE_NAME, "subscriber-example")
+            .build();
+
+    // Creates a Cloud Trace exporter.
+    SpanExporter traceExporter =
+        TraceExporter.createWithConfiguration(
+            TraceConfiguration.builder().setProjectId(projectId).build());
+
+    SdkTracerProvider sdkTracerProvider =
+        SdkTracerProvider.builder()
+            .setResource(resource)
+            .addSpanProcessor(SimpleSpanProcessor.create(traceExporter))
+            .setSampler(Sampler.alwaysOn())
+            .build();
+
+    OpenTelemetry openTelemetry =
+        OpenTelemetrySdk.builder().setTracerProvider(sdkTracerProvider).buildAndRegisterGlobal();
+
+    ProjectSubscriptionName subscriptionName =
+        ProjectSubscriptionName.of(projectId, subscriptionId);
+
+    // Instantiate an asynchronous message receiver.
+    MessageReceiver receiver =
+        (PubsubMessage message, AckReplyConsumer consumer) -> {
+          // Handle incoming message, then ack the received message.
+          System.out.println("Id: " + message.getMessageId());
+          System.out.println("Data: " + message.getData().toStringUtf8());
+          consumer.ack();
+        };
+
+    Subscriber subscriber = null;
+    try {
+      subscriber =
+          Subscriber.newBuilder(subscriptionName, receiver)
+              .setOpenTelemetry(openTelemetry)
+              .setEnableOpenTelemetryTracing(true)
+              .build();
+
+      // Start the subscriber.
+      subscriber.startAsync().awaitRunning();
+      System.out.printf("Listening for messages on %s:\n", subscriptionName.toString());
+      // Allow the subscriber to run for 30s unless an unrecoverable error occurs.
+      subscriber.awaitTerminated(30, TimeUnit.SECONDS);
+    } catch (TimeoutException timeoutException) {
+      // Shut down the subscriber after 30s. Stop receiving messages.
+      subscriber.stopAsync();
+    }
+  }
+}
+ // [END pubsub_subscribe_otel_tracing]