Add gRPC request metadata instrumentation

instrumentation/grpc-1.6/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/grpc/v1_6/GrpcSingletons.java

@@ -5,13 +5,16 @@
 
 package io.opentelemetry.javaagent.instrumentation.grpc.v1_6;
 
+import static java.util.Collections.emptyList;
+
 import io.grpc.ClientInterceptor;
 import io.grpc.Context;
 import io.grpc.ServerInterceptor;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.instrumentation.grpc.v1_6.GrpcTelemetry;
 import io.opentelemetry.instrumentation.grpc.v1_6.internal.ContextStorageBridge;
 import io.opentelemetry.javaagent.bootstrap.internal.InstrumentationConfig;
+import java.util.List;
 
 // Holds singleton references.
 public final class GrpcSingletons {
@@ -27,9 +30,14 @@ public final class GrpcSingletons {
         InstrumentationConfig.get()
             .getBoolean("otel.instrumentation.grpc.experimental-span-attributes", false);
 
+    List<String> rpcRequestMetadata =
+        InstrumentationConfig.get()
+            .getList("otel.instrumentation.rpc.capture-metadata.request", emptyList());
+
     GrpcTelemetry telemetry =
         GrpcTelemetry.builder(GlobalOpenTelemetry.get())
             .setCaptureExperimentalSpanAttributes(experimentalSpanAttributes)
+            .setCapturedRequestMetadata(rpcRequestMetadata)
             .build();
 
     CLIENT_INTERCEPTOR = telemetry.newClientInterceptor();

instrumentation/grpc-1.6/library/src/main/java/io/opentelemetry/instrumentation/grpc/v1_6/CapturedGrpcMetadataUtil.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.grpc.v1_6;
+
+import static java.util.Collections.unmodifiableList;
+
+import io.opentelemetry.api.common.AttributeKey;
+import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.stream.Collectors;
+
+final class CapturedGrpcMetadataUtil {
+  private static final String RPC_REQUEST_METADATA_KEY_ATTRIBUTE_PREFIX = "rpc.request.metadata.";
+  private static final ConcurrentMap<String, AttributeKey<List<String>>> requestKeysCache =
+      new ConcurrentHashMap<>();
+
+  static List<String> lowercase(List<String> names) {
+    if (names == null) {
+      return Collections.emptyList();
+    }
+
+    return unmodifiableList(
+        names.stream().map(s -> s.toLowerCase(Locale.ROOT)).collect(Collectors.toList()));
+  }
+
+  static AttributeKey<List<String>> requestAttributeKey(String metadataKey) {
+    return requestKeysCache.computeIfAbsent(
+        metadataKey, CapturedGrpcMetadataUtil::createRequestKey);
+  }
+
+  private static AttributeKey<List<String>> createRequestKey(String metadataKey) {
+    return AttributeKey.stringArrayKey(RPC_REQUEST_METADATA_KEY_ATTRIBUTE_PREFIX + metadataKey);
+  }
+
+  private CapturedGrpcMetadataUtil() {}
+}

instrumentation/grpc-1.6/library/src/main/java/io/opentelemetry/instrumentation/grpc/v1_6/GrpcAttributesExtractor.java

@@ -5,18 +5,31 @@
 
 package io.opentelemetry.instrumentation.grpc.v1_6;
 
+import static io.opentelemetry.instrumentation.grpc.v1_6.CapturedGrpcMetadataUtil.lowercase;
+import static io.opentelemetry.instrumentation.grpc.v1_6.CapturedGrpcMetadataUtil.requestAttributeKey;
+
 import io.grpc.Status;
 import io.opentelemetry.api.common.AttributesBuilder;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.instrumentation.api.instrumenter.AttributesExtractor;
 import io.opentelemetry.semconv.trace.attributes.SemanticAttributes;
+import java.util.List;
 import javax.annotation.Nullable;
 
 final class GrpcAttributesExtractor implements AttributesExtractor<GrpcRequest, Status> {
+  private final GrpcRpcAttributesGetter getter;
+  private final List<String> capturedRequestMetadata;
+
+  GrpcAttributesExtractor(
+      GrpcRpcAttributesGetter getter, List<String> requestMetadataValuesToCapture) {
+    this.getter = getter;
+    this.capturedRequestMetadata = lowercase(requestMetadataValuesToCapture);
+  }
+
   @Override
   public void onStart(
       AttributesBuilder attributes, Context parentContext, GrpcRequest grpcRequest) {
-    // No request attributes
+    // Request attributes captured on request end
   }
 
   @Override
@@ -29,5 +42,14 @@ public void onEnd(
     if (status != null) {
       attributes.put(SemanticAttributes.RPC_GRPC_STATUS_CODE, status.getCode().value());
     }
+
+    if (capturedRequestMetadata != null) {
+      for (String key : capturedRequestMetadata) {
+        List<String> value = getter.metadataValue(request, key);
+        if (value != null) {
+          attributes.put(requestAttributeKey(key), value);
+        }
+      }
+    }
   }
 }

instrumentation/grpc-1.6/library/src/main/java/io/opentelemetry/instrumentation/grpc/v1_6/GrpcRpcAttributesGetter.java

@@ -5,7 +5,12 @@
 
 package io.opentelemetry.instrumentation.grpc.v1_6;
 
+import io.grpc.Metadata;
 import io.opentelemetry.instrumentation.api.instrumenter.rpc.RpcAttributesGetter;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
 import javax.annotation.Nullable;
 
 enum GrpcRpcAttributesGetter implements RpcAttributesGetter<GrpcRequest> {
@@ -37,4 +42,23 @@ public String method(GrpcRequest request) {
     }
     return fullMethodName.substring(slashIndex + 1);
   }
+
+  List<String> metadataValue(GrpcRequest request, String key) {
+    if (request.getMetadata() == null) {
+      return Collections.emptyList();
+    }
+
+    if (key == null || key.isEmpty()) {
+      return Collections.emptyList();
+    }
+
+    Iterable<String> values =
+        request.getMetadata().getAll(Metadata.Key.of(key, Metadata.ASCII_STRING_MARSHALLER));
+
+    if (values == null) {
+      return Collections.emptyList();
+    }
+
+    return StreamSupport.stream(values.spliterator(), false).collect(Collectors.toList());
+  }
 }

instrumentation/grpc-1.6/library/src/main/java/io/opentelemetry/instrumentation/grpc/v1_6/GrpcTelemetryBuilder.java

@@ -50,6 +50,7 @@ public final class GrpcTelemetryBuilder {
       additionalClientExtractors = new ArrayList<>();
 
   private boolean captureExperimentalSpanAttributes;
+  private List<String> requestMetadataValuesToCapture;
 
   GrpcTelemetryBuilder(OpenTelemetry openTelemetry) {
     this.openTelemetry = openTelemetry;
@@ -115,6 +116,13 @@ public GrpcTelemetryBuilder setCaptureExperimentalSpanAttributes(
     return this;
   }
 
+  /** Sets which metadata request values should be captured as span attributes. */
+  @CanIgnoreReturnValue
+  public GrpcTelemetryBuilder setCapturedRequestMetadata(List<String> capturedRequestMetadata) {
+    this.requestMetadataValuesToCapture = capturedRequestMetadata;
+    return this;
+  }
+
   /** Returns a new {@link GrpcTelemetry} with the settings of this {@link GrpcTelemetryBuilder}. */
   public GrpcTelemetry build() {
     SpanNameExtractor<GrpcRequest> originalSpanNameExtractor = new GrpcSpanNameExtractor();
@@ -139,7 +147,9 @@ public GrpcTelemetry build() {
             instrumenter ->
                 instrumenter
                     .setSpanStatusExtractor(new GrpcSpanStatusExtractor())
-                    .addAttributesExtractor(new GrpcAttributesExtractor())
+                    .addAttributesExtractor(
+                        new GrpcAttributesExtractor(
+                            GrpcRpcAttributesGetter.INSTANCE, requestMetadataValuesToCapture))
                     .addAttributesExtractors(additionalExtractors));
 
     GrpcNetClientAttributesGetter netClientAttributesGetter = new GrpcNetClientAttributesGetter();

instrumentation/grpc-1.6/library/src/test/java/io/opentelemetry/instrumentation/grpc/v1_6/GrpcTest.java

@@ -24,6 +24,8 @@
 import io.opentelemetry.instrumentation.testing.junit.InstrumentationExtension;
 import io.opentelemetry.instrumentation.testing.junit.LibraryInstrumentationExtension;
 import io.opentelemetry.sdk.testing.assertj.OpenTelemetryAssertions;
+import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 import javax.annotation.Nullable;
 import org.junit.jupiter.api.Test;
@@ -35,6 +37,7 @@ class GrpcTest extends AbstractGrpcTest {
   static final InstrumentationExtension testing = LibraryInstrumentationExtension.create();
 
   private static final AttributeKey<String> CUSTOM_KEY = AttributeKey.stringKey("customKey");
+  private static final String METADATA_ATTRIBUTE_PREFIX = "rpc.request.metadata.";
 
   private static final Metadata.Key<String> CUSTOM_METADATA_KEY =
       Metadata.Key.of("customMetadataKey", Metadata.ASCII_STRING_MARSHALLER);
@@ -56,6 +59,83 @@ protected InstrumentationExtension testing() {
     return testing;
   }
 
+  @Test
+  void grpcAttributesExtractor() throws Exception {
+    String metadataKey = "some-key";
+    AttributeKey<List<String>> attributeKey =
+        AttributeKey.stringArrayKey(METADATA_ATTRIBUTE_PREFIX + metadataKey);
+    String metadataValue = "some-value";
+    List<String> metadataValueAsList = Collections.singletonList("some-value");
+
+    BindableService greeter =
+        new GreeterGrpc.GreeterImplBase() {
+          @Override
+          public void sayHello(
+              Helloworld.Request req, StreamObserver<Helloworld.Response> responseObserver) {
+            Helloworld.Response reply =
+                Helloworld.Response.newBuilder().setMessage("Hello " + req.getName()).build();
+            responseObserver.onNext(reply);
+            responseObserver.onCompleted();
+          }
+        };
+
+    GrpcAttributesExtractor grpcAttributesExtractor =
+        new GrpcAttributesExtractor(
+            GrpcRpcAttributesGetter.INSTANCE, Collections.singletonList(metadataKey));
+
+    Server server =
+        ServerBuilder.forPort(0)
+            .addService(greeter)
+            .intercept(
+                GrpcTelemetry.builder(testing.getOpenTelemetry())
+                    .addAttributeExtractor(grpcAttributesExtractor)
+                    .build()
+                    .newServerInterceptor())
+            .build()
+            .start();
+
+    ManagedChannel channel =
+        createChannel(
+            ManagedChannelBuilder.forAddress("localhost", server.getPort())
+                .intercept(
+                    GrpcTelemetry.builder(testing.getOpenTelemetry())
+                        .addAttributeExtractor(grpcAttributesExtractor)
+                        .build()
+                        .newClientInterceptor()));
+
+    Metadata extraMetadata = new Metadata();
+    extraMetadata.put(
+        Metadata.Key.of(metadataKey, Metadata.ASCII_STRING_MARSHALLER), metadataValue);
+
+    GreeterGrpc.GreeterBlockingStub client =
+        GreeterGrpc.newBlockingStub(channel)
+            .withInterceptors(MetadataUtils.newAttachHeadersInterceptor(extraMetadata));
+
+    Helloworld.Response response =
+        testing()
+            .runWithSpan(
+                "parent",
+                () -> client.sayHello(Helloworld.Request.newBuilder().setName("test").build()));
+
+    OpenTelemetryAssertions.assertThat(response.getMessage()).isEqualTo("Hello test");
+
+    testing()
+        .waitAndAssertTraces(
+            trace ->
+                trace.hasSpansSatisfyingExactly(
+                    span -> span.hasName("parent").hasKind(SpanKind.INTERNAL).hasNoParent(),
+                    span ->
+                        span.hasName("example.Greeter/SayHello")
+                            .hasKind(SpanKind.CLIENT)
+                            .hasParent(trace.getSpan(0))
+                            .hasAttribute(attributeKey, metadataValueAsList),
+                    span ->
+                        span.hasName("example.Greeter/SayHello")
+                            .hasKind(SpanKind.SERVER)
+                            .hasParent(trace.getSpan(1))
+                            .hasAttribute(attributeKey, metadataValueAsList)));
+  }
+
   @Test
   void metadataProvided() throws Exception {
     BindableService greeter =