feat: Add more attributes to golden signals metrics.

gax-java/dependencies.properties

@@ -41,6 +41,7 @@ maven.com_google_auth_google_auth_library_oauth2_http=com.google.auth:google-aut
 maven.com_google_auth_google_auth_library_credentials=com.google.auth:google-auth-library-credentials:1.42.1
 maven.io_opentelemetry_opentelemetry_api=io.opentelemetry:opentelemetry-api:1.47.0
 maven.io_opentelemetry_opentelemetry_context=io.opentelemetry:opentelemetry-context:1.47.0
+maven.io_opentelemetry_opentelemetry_sdk_testing=io.opentelemetry:opentelemetry_sdk_testing:1.47.0
 maven.io_opencensus_opencensus_api=io.opencensus:opencensus-api:0.31.1
 maven.io_opencensus_opencensus_contrib_grpc_metrics=io.opencensus:opencensus-contrib-grpc-metrics:0.31.1
 maven.io_opencensus_opencensus_contrib_http_util=io.opencensus:opencensus-contrib-http-util:0.31.1

gax-java/gax/pom.xml

@@ -78,6 +78,11 @@
       <artifactId>opentelemetry-context</artifactId>
       <optional>true</optional>
     </dependency>
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-sdk-testing</artifactId>
+      <scope>test</scope>
+    </dependency>
     <!--    Logging dependency    -->
     <dependency>
       <groupId>org.slf4j</groupId>

gax-java/gax/src/main/java/com/google/api/gax/rpc/LibraryMetadata.java

@@ -51,6 +51,9 @@ public abstract class LibraryMetadata {
   @Nullable
   public abstract String artifactName();
 
+  @Nullable
+  public abstract String version();
+
   public static LibraryMetadata empty() {
     return newBuilder().build();
   }
@@ -65,6 +68,8 @@ public abstract static class Builder {
 
     public abstract Builder setArtifactName(@Nullable String artifactName);
 
+    public abstract Builder setVersion(@Nullable String version);
+
     public abstract LibraryMetadata build();
   }
 }

gax-java/gax/src/main/java/com/google/api/gax/tracing/ApiTracerContext.java

@@ -33,9 +33,22 @@
 import com.google.api.core.InternalApi;
 import com.google.api.gax.rpc.LibraryMetadata;
 import com.google.auto.value.AutoValue;
+import org.apache.http.protocol.HTTP;
+
 import java.util.HashMap;
 import java.util.Map;
 import javax.annotation.Nullable;
+//gcp.client.service [consistent across T4 spans]
+//gcp.client.version [consistent across T4 spans]
+//        rpc.system.name (e.g., grpc, http) [consistent across T4 spans]
+//        rpc.response.status_code (for gRPC and HTTP) [from last T4 span]
+//        rpc.method (for gRPC and HTTP) [from the last T4 span]
+//url.domain [consistent across T4 spans]
+//        url.template (for HTTP) [from the first T4 span]
+//        http.response.status_code (for HTTP) [from the last T4 span]
+//server.address [from the last T4 span]
+//server.port [from the last T4 span]
+//        error.type (if the overall T3 operation failed)
 
 /**
  * A context object that contains information used to infer attributes that are common for all
@@ -51,6 +64,15 @@ public abstract class ApiTracerContext {
 
   public abstract LibraryMetadata libraryMetadata();
 
+  @Nullable
+  public abstract String serviceName();
+
+  @Nullable
+  public abstract String urlDomain();
+
+  @Nullable
+  public abstract String urlTemplate();
+
   /**
    * @return a map of attributes to be included in attempt-level spans
    */
@@ -68,6 +90,25 @@ public Map<String, String> getAttemptAttributes() {
     return attributes;
   }
 
+  Map<String, String> getMetricsAttributes() {
+    Map<String, String> attributes = new HashMap<>();
+    if (serverAddress() != null) {
+      attributes.put(ObservabilityAttributes.SERVER_ADDRESS_ATTRIBUTE, serverAddress());
+    }
+    if (serviceName() != null) {
+      attributes.put("gcp.client.service", serviceName());
+    }
+    if (transport() == HTTP) {
+      if (urlDomain() != null) {
+        attributes.put("url.domain", serviceName());
+      }
+      if (serviceName() != null) {
+        attributes.put("url.template", serviceName());
+      }
+    }
+    return attributes;
+  }
+
   public static ApiTracerContext empty() {
     return newBuilder().setLibraryMetadata(LibraryMetadata.empty()).build();
   }

gax-java/gax/src/main/java/com/google/api/gax/tracing/GoldenSignalMetricsTracer.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.tracing;
+
+import static com.google.api.gax.tracing.ObservabilityAttributes.RPC_RESPONSE_STATUS_ATTRIBUTE;
+
+import com.google.api.gax.rpc.StatusCode;
+import com.google.common.base.Stopwatch;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * This class computes golden signal metrics that can be observed in the lifecycle of an RPC
+ * operation. The responsibility of recording metrics should delegate to {@link
+ * GoldenSignalsMetricsRecorder}, hence this class should not have any knowledge about the
+ * observability framework (e.g. OpenTelemetry).
+ */
+class GoldenSignalMetricsTracer implements ApiTracer {
+  private final Stopwatch clientRequestTimer = Stopwatch.createStarted();
+  private final GoldenSignalsMetricsRecorder metricsRecorder;
+  private final Map<String, String> attributes = new HashMap<>();
+  private final ApiTracerContext apiTracerContext;
+
+  /**
+   * Creates the following instruments for the following metrics:
+   *
+   * <ul>
+   *   <li>Client Request Duration: Histogram
+   * </ul>
+   *
+   * @param metricsRecorder  OpenTelemetry
+   * @param apiTracerContext
+   */
+  GoldenSignalMetricsTracer(GoldenSignalsMetricsRecorder metricsRecorder, ApiTracerContext apiTracerContext) {
+    this.metricsRecorder = metricsRecorder;
+    this.apiTracerContext = apiTracerContext;
+  }
+
+  @Override
+  public void operationSucceeded() {
+    attributes.put(RPC_RESPONSE_STATUS_ATTRIBUTE, StatusCode.Code.OK.toString());
+    attributes.putAll(apiTracerContext.getMetricsAttributes());
+    metricsRecorder.recordOperationLatency(
+        clientRequestTimer.elapsed(TimeUnit.SECONDS), attributes);
+  }
+
+  @Override
+  public void operationCancelled() {
+    attributes.put(RPC_RESPONSE_STATUS_ATTRIBUTE, StatusCode.Code.CANCELLED.toString());
+    attributes.putAll(apiTracerContext.getMetricsAttributes());
+    metricsRecorder.recordOperationLatency(
+        clientRequestTimer.elapsed(TimeUnit.SECONDS), attributes);
+  }
+
+  @Override
+  public void operationFailed(Throwable error) {
+    attributes.put(RPC_RESPONSE_STATUS_ATTRIBUTE, ObservabilityUtils.extractStatus(error));
+    attributes.putAll(apiTracerContext.getMetricsAttributes());
+    metricsRecorder.recordOperationLatency(
+        clientRequestTimer.elapsed(TimeUnit.SECONDS), attributes);
+  }
+}

gax-java/gax/src/main/java/com/google/api/gax/tracing/GoldenSignalMetricsTracerFactory.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.tracing;
+
+import com.google.api.core.BetaApi;
+import com.google.api.core.InternalApi;
+import io.opentelemetry.api.OpenTelemetry;
+
+/**
+ * A {@link ApiTracerFactory} to build instances of {@link GoldenSignalMetricsTracer}.
+ *
+ * <p>This class is expected to be initialized once during client initialization.
+ */
+@BetaApi
+@InternalApi
+public class GoldenSignalMetricsTracerFactory implements ApiTracerFactory {
+
+  private ApiTracerContext apiTracerContext;
+  private final OpenTelemetry openTelemetry;
+  private GoldenSignalsMetricsRecorder metricsRecorder;
+
+  public GoldenSignalMetricsTracerFactory(OpenTelemetry openTelemetry) {
+    this.openTelemetry = openTelemetry;
+  }
+
+  @Override
+  public ApiTracer newTracer(ApiTracer parent, SpanName spanName, OperationType operationType) {
+    if (metricsRecorder == null) {
+      // This should never happen, in case it happens, create a no-op api tracer to not block
+      // regular requests.
+      return new BaseApiTracer();
+    }
+    return new GoldenSignalMetricsTracer(metricsRecorder, apiTracerContext);
+  }
+
+  @Override
+  public ApiTracerFactory withContext(ApiTracerContext context) {
+    this.apiTracerContext = context;
+    this.metricsRecorder =
+        new GoldenSignalsMetricsRecorder(
+            openTelemetry, apiTracerContext.libraryMetadata().artifactName());
+    return this;
+  }
+}

gax-java/gax/src/main/java/com/google/api/gax/tracing/GoldenSignalsMetricsRecorder.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.tracing;
+
+import io.opentelemetry.api.OpenTelemetry;
+import io.opentelemetry.api.metrics.DoubleHistogram;
+import io.opentelemetry.api.metrics.Meter;
+import java.util.Map;
+
+/**
+ * This class takes an OpenTelemetry object, and creates instruments (meters, histograms etc.) from
+ * it for recording golden signal metrics. There must be only one instance of
+ * GoldenSignalsMetricsRecorder per client, all the methods in this class are expected to be called
+ * from multiple threads, hence they need to be thread safe.
+ */
+class GoldenSignalsMetricsRecorder {
+  static final String CLIENT_REQUEST_DURATION_METRIC_NAME = "gcp.client.request.duration";
+  static final String CLIENT_REQUEST_DURATION_METRIC_DESCRIPTION =
+      "Measures the total time taken for a logical client request, including any retries, backoff, and pre/post-processing";
+
+  final DoubleHistogram clientRequestDurationRecorder;
+
+  GoldenSignalsMetricsRecorder(OpenTelemetry openTelemetry, String libraryName) {
+    Meter meter = openTelemetry.meterBuilder(libraryName).build();
+
+    this.clientRequestDurationRecorder =
+        meter
+            .histogramBuilder(CLIENT_REQUEST_DURATION_METRIC_NAME)
+            .setDescription(CLIENT_REQUEST_DURATION_METRIC_DESCRIPTION)
+            .setUnit("s")
+            .build();
+  }
+
+  void recordOperationLatency(double operationLatency, Map<String, String> attributes) {
+    clientRequestDurationRecorder.record(
+        operationLatency, ObservabilityUtils.toOtelAttributes(attributes));
+  }
+}