Add autoconfiguration auth extension example

examples/autoconf-auth-extension/README.md

@@ -0,0 +1,40 @@
+# OTLP Trace and Metrics with Google Auth Extension Example
+
+This sample demonstrates how to use the [OpenTelemetry GCP Auth Extension](https://github.com/open-telemetry/opentelemetry-java-contrib/tree/main/gcp-auth-extension) to configure the OpenTelemetry SDK in a manually instrumented application and export telemetry to Google Cloud using OTLP exporters for both traces and metrics.
+
+## Prerequisites
+
+First, ensure you have Google Cloud credentials available on your machine:
+
+```shell
+gcloud auth application-default login
+```
+
+Executing this command will save your application credentials to the default path:
+ - Linux, macOS: `$HOME/.config/gcloud/application_default_credentials.json`
+ - Windows: `%APPDATA%\gcloud\application_default_credentials.json`
+
+Next, set the `GOOGLE_CLOUD_PROJECT` environment variable to your GCP project ID:
+```shell
+export GOOGLE_CLOUD_PROJECT="your-gcp-project-id"
+```
+This environment variable is used by the GCP Auth Extension to identify the project.
+
+## Running the Sample
+
+To run the sample from the repository root, use the following Gradle command:
+
+```shell
+./gradlew :examples-autoconf-auth-extension:run
+```
+
+Running this sample will generate traces and metrics and export them to Google Cloud via OTLP.
+
+## Configuration Details
+
+The sample uses OpenTelemetry SDK Autoconfigure. The following system properties are configured in `build.gradle` and can be overridden or set as environment variables:
+
+- `otel.exporter.otlp.endpoint`: Set to `https://telemetry.googleapis.com` for Google Cloud OTLP receiver.
+- `otel.traces.exporter`: Set to `otlp` to use OTLP exporter for traces.
+- `otel.metrics.exporter`: Set to `otlp` to use OTLP exporter for metrics.
+- `otel.exporter.otlp.protocol`: Set to `http/protobuf` as required by Google Cloud OTLP receiver.

examples/autoconf-auth-extension/build.gradle

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2026 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.
+ */
+plugins {
+	id 'java'
+	id 'application'
+}
+
+// examples are not published, so version can be hardcoded
+version = '0.1.0'
+
+description = 'Example showing OTLP exporter with GCP Auth Extension for traces and metrics'
+
+dependencies {
+	implementation(libraries.opentelemetry_api)
+	implementation(libraries.opentelemetry_sdk)
+	implementation(libraries.opentelemetry_otlp_exporter)
+	implementation(libraries.opentelemetry_sdk_autoconf)
+	implementation(libraries.opentelemetry_gcp_auth_extension)
+	implementation(libraries.opentelemetry_gcp_resources)
+}
+
+def autoconf_config = [
+	'-Dotel.exporter.otlp.endpoint=https://telemetry.googleapis.com',
+	'-Dotel.traces.exporter=otlp',
+	'-Dotel.metrics.exporter=otlp',
+	'-Dotel.logs.exporter=none',
+	'-Dotel.service.name=autoconf-auth-extension-example',
+	'-Dotel.exporter.otlp.protocol=http/protobuf',
+]
+
+application {
+	mainClassName = 'com.google.cloud.opentelemetry.example.autoconfauthextension.AutoconfAuthExtensionExample'
+	applicationDefaultJvmArgs = autoconf_config
+}

examples/autoconf-auth-extension/src/main/java/com/google/cloud/opentelemetry/example/autoconfauthextension/AutoconfAuthExtensionExample.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2026 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 com.google.cloud.opentelemetry.example.autoconfauthextension;
+
+import io.opentelemetry.api.metrics.LongCounter;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.context.Scope;
+import io.opentelemetry.sdk.OpenTelemetrySdk;
+import io.opentelemetry.sdk.autoconfigure.AutoConfiguredOpenTelemetrySdk;
+import io.opentelemetry.sdk.common.CompletableResultCode;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+
+public class AutoconfAuthExtensionExample {
+  private static final String INSTRUMENTATION_SCOPE_NAME =
+      AutoconfAuthExtensionExample.class.getName();
+  private static final Random RANDOM = new Random();
+
+  private static OpenTelemetrySdk openTelemetrySdk;
+
+  private static void myUseCase(String description, LongCounter counter) {
+    // Generate a span
+    Span span =
+        openTelemetrySdk.getTracer(INSTRUMENTATION_SCOPE_NAME).spanBuilder(description).startSpan();
+    try (Scope scope = span.makeCurrent()) {
+      span.addEvent("Event A");
+      // Do some work for the use case
+      for (int i = 0; i < 3; i++) {
+        String work = String.format("%s - Work #%d", description, (i + 1));
+        doWork(work, counter);
+      }
+      span.addEvent("Event B");
+    } finally {
+      span.end();
+    }
+  }
+
+  private static void doWork(String description, LongCounter counter) {
+    // Child span
+    Span span =
+        openTelemetrySdk.getTracer(INSTRUMENTATION_SCOPE_NAME).spanBuilder(description).startSpan();
+    try (Scope scope = span.makeCurrent()) {
+      // Simulate work: this could be simulating a network request or an expensive disk operation
+      int randomSleep = RANDOM.nextInt(5) * 100;
+      span.setAttribute("RandomSleep", randomSleep);
+      Thread.sleep(100 + randomSleep);
+
+      // Record a metric
+      counter.add(1);
+    } catch (InterruptedException e) {
+      throw new RuntimeException(e);
+    } finally {
+      span.end();
+    }
+  }
+
+  public static void main(String[] args) {
+    // Configure the OpenTelemetry pipeline with Auto configuration
+    // The gcp-auth-extension is picked up automatically via SPI if present on classpath
+    openTelemetrySdk = AutoConfiguredOpenTelemetrySdk.initialize().getOpenTelemetrySdk();
+
+    // Create a counter
+    LongCounter counter =
+        openTelemetrySdk
+            .getMeter(INSTRUMENTATION_SCOPE_NAME)
+            .counterBuilder("example_work_counter")
+            .setDescription("Counts the number of work items processed")
+            .setUnit("1")
+            .build();
+
+    // Application-specific logic
+    myUseCase("One", counter);
+    myUseCase("Two", counter);
+
+    System.out.println("Telemetry generated. Shutting down SDK...");
+
+    // Flush all buffered telemetry
+    CompletableResultCode traceShutdown = openTelemetrySdk.getSdkTracerProvider().shutdown();
+    CompletableResultCode meterShutdown = openTelemetrySdk.getSdkMeterProvider().shutdown();
+
+    // Wait for export to finish
+    traceShutdown.join(10000, TimeUnit.MILLISECONDS);
+    meterShutdown.join(10000, TimeUnit.MILLISECONDS);
+
+    System.out.println("SDK shut down complete.");
+  }
+}

settings.gradle

@@ -43,6 +43,7 @@ include ":examples-spring"
 include ":propagators-gcp"
 include ":shared-resourcemapping"
 include ":examples-autoinstrument-auth-extension"
+include ":examples-autoconf-auth-extension"
 
 def javaVersion = Jvm.current().javaVersion
 
@@ -107,3 +108,6 @@ project(':examples-otlpmetric').projectDir =
 
 project(':examples-autoinstrument-auth-extension').projectDir =
 		"$rootDir/examples/autoinstrument-auth-extension" as File
+
+project(':examples-autoconf-auth-extension').projectDir =
+		"$rootDir/examples/autoconf-auth-extension" as File