Implement HttpServerResponseCustomizer support for Armeria (#8274)

instrumentation/armeria-1.3/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/armeria/v1_3/ArmeriaHttpResponseMutator.java

@@ -0,0 +1,18 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.armeria.v1_3;
+
+import com.linecorp.armeria.common.ResponseHeadersBuilder;
+import io.opentelemetry.javaagent.bootstrap.http.HttpServerResponseMutator;
+
+enum ArmeriaHttpResponseMutator implements HttpServerResponseMutator<ResponseHeadersBuilder> {
+  INSTANCE;
+
+  @Override
+  public void appendHeader(ResponseHeadersBuilder response, String name, String value) {
+    response.add(name, value);
+  }
+}

instrumentation/armeria-1.3/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/armeria/v1_3/ArmeriaSingletons.java

@@ -35,7 +35,10 @@ public final class ArmeriaSingletons {
             .build();
 
     CLIENT_DECORATOR = telemetry.newClientDecorator();
-    SERVER_DECORATOR = telemetry.newServiceDecorator();
+    SERVER_DECORATOR =
+        telemetry
+            .newServiceDecorator()
+            .compose(service -> new ResponseCustomizingDecorator(service));
   }
 
   private ArmeriaSingletons() {}

instrumentation/armeria-1.3/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/armeria/v1_3/ResponseCustomizingDecorator.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.armeria.v1_3;
+
+import com.linecorp.armeria.common.FilteredHttpResponse;
+import com.linecorp.armeria.common.HttpObject;
+import com.linecorp.armeria.common.HttpRequest;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.common.ResponseHeaders;
+import com.linecorp.armeria.common.ResponseHeadersBuilder;
+import com.linecorp.armeria.server.HttpService;
+import com.linecorp.armeria.server.ServiceRequestContext;
+import com.linecorp.armeria.server.SimpleDecoratingHttpService;
+import io.opentelemetry.context.Context;
+import io.opentelemetry.javaagent.bootstrap.http.HttpServerResponseCustomizerHolder;
+
+class ResponseCustomizingDecorator extends SimpleDecoratingHttpService {
+
+  ResponseCustomizingDecorator(HttpService delegate) {
+    super(delegate);
+  }
+
+  @Override
+  public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) throws Exception {
+    HttpResponse response = unwrap().serve(ctx, req);
+    Context context = Context.current();
+    return new FilteredHttpResponse(response) {
+      @Override
+      public HttpObject filter(HttpObject obj) {
+        // Ignore other objects like HttpData.
+        if (!(obj instanceof ResponseHeaders)) {
+          return obj;
+        }
+
+        ResponseHeaders headers = (ResponseHeaders) obj;
+        ResponseHeadersBuilder headersBuilder = headers.toBuilder();
+        HttpServerResponseCustomizerHolder.getCustomizer()
+            .customize(context, headersBuilder, ArmeriaHttpResponseMutator.INSTANCE);
+
+        return headersBuilder.build();
+      }
+    };
+  }
+}

instrumentation/armeria-1.3/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/armeria/v1_3/ArmeriaHttpServerTest.java

@@ -9,6 +9,8 @@
 import io.opentelemetry.instrumentation.armeria.v1_3.AbstractArmeriaHttpServerTest;
 import io.opentelemetry.instrumentation.testing.junit.InstrumentationExtension;
 import io.opentelemetry.instrumentation.testing.junit.http.HttpServerInstrumentationExtension;
+import io.opentelemetry.instrumentation.testing.junit.http.HttpServerTestOptions;
+import io.opentelemetry.instrumentation.testing.junit.http.ServerEndpoint;
 import org.junit.jupiter.api.extension.RegisterExtension;
 
 class ArmeriaHttpServerTest extends AbstractArmeriaHttpServerTest {
@@ -20,4 +22,11 @@ class ArmeriaHttpServerTest extends AbstractArmeriaHttpServerTest {
   protected ServerBuilder configureServer(ServerBuilder sb) {
     return sb;
   }
+
+  @Override
+  protected void configure(HttpServerTestOptions options) {
+    super.configure(options);
+    options.setHasResponseCustomizer(
+        endpoint -> ServerEndpoint.NOT_FOUND != endpoint && ServerEndpoint.EXCEPTION != endpoint);
+  }
 }

instrumentation/armeria-1.3/testing/src/main/java/io/opentelemetry/instrumentation/armeria/v1_3/AbstractArmeriaHttpServerTest.java

@@ -176,7 +176,7 @@ protected void stopServer(Server server) {
   }
 
   @Override
-  protected final void configure(HttpServerTestOptions options) {
+  protected void configure(HttpServerTestOptions options) {
     options.setExpectedHttpRoute(
         endpoint -> {
           if (endpoint == ServerEndpoint.NOT_FOUND) {