Fix armeria server instrumentation for http2

instrumentation/armeria-1.3/javaagent/build.gradle.kts

@@ -16,6 +16,7 @@ dependencies {
   testInstrumentation(project(":instrumentation:netty:netty-4.1:javaagent"))
 
   library("com.linecorp.armeria:armeria:1.3.0")
+  testLibrary("com.linecorp.armeria:armeria-junit5:1.3.0")
 
   testImplementation(project(":instrumentation:armeria-1.3:testing"))
 }

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

@@ -38,7 +38,11 @@ public final class ArmeriaSingletons {
             .build();
 
     CLIENT_DECORATOR = telemetry.newClientDecorator();
-    SERVER_DECORATOR = service -> new ServerDecorator(service);
+    Function<? super HttpService, ? extends HttpService> libraryDecorator =
+        telemetry
+            .newServiceDecorator()
+            .compose(service -> new ResponseCustomizingDecorator(service));
+    SERVER_DECORATOR = service -> new ServerDecorator(service, libraryDecorator.apply(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/main/java/io/opentelemetry/javaagent/instrumentation/armeria/v1_3/ServerDecorator.java

@@ -14,17 +14,27 @@
 import io.opentelemetry.api.trace.StatusCode;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.instrumentation.api.instrumenter.ErrorCauseExtractor;
+import io.opentelemetry.instrumentation.api.instrumenter.LocalRootSpan;
 import io.opentelemetry.instrumentation.api.instrumenter.http.HttpServerRoute;
 import io.opentelemetry.instrumentation.api.instrumenter.http.HttpServerRouteSource;
 
 class ServerDecorator extends SimpleDecoratingHttpService {
+  private final HttpService libraryDelegate;
 
-  ServerDecorator(HttpService delegate) {
+  ServerDecorator(HttpService delegate, HttpService libraryDelegate) {
     super(delegate);
+    this.libraryDelegate = libraryDelegate;
   }
 
   @Override
   public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) throws Exception {
+    // If there is no server span fall back to armeria liberary instrumentation. Server span is
+    // usually created by netty instrumentation, it can be missing when netty instrumentation is
+    // disabled or when http2 is used (netty instrumentation does not support http2).
+    if (!LocalRootSpan.current().getSpanContext().isValid()) {
+      return libraryDelegate.serve(ctx, req);
+    }
+
     String matchedRoute = ctx.config().route().patternString();
     if (matchedRoute == null || matchedRoute.isEmpty()) {
       matchedRoute = "/";

instrumentation/armeria-1.3/javaagent/src/test/java/io/opentelemetry/javaagent/instrumentation/armeria/v1_3/ArmeriaHttp2Test.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.javaagent.instrumentation.armeria.v1_3;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.linecorp.armeria.client.WebClient;
+import com.linecorp.armeria.common.AggregatedHttpResponse;
+import com.linecorp.armeria.common.HttpResponse;
+import com.linecorp.armeria.server.ServerBuilder;
+import com.linecorp.armeria.testing.junit5.server.ServerExtension;
+import io.opentelemetry.api.trace.SpanKind;
+import io.opentelemetry.instrumentation.testing.junit.AgentInstrumentationExtension;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+class ArmeriaHttp2Test {
+  @RegisterExtension
+  static final AgentInstrumentationExtension testing = AgentInstrumentationExtension.create();
+
+  @RegisterExtension
+  static ServerExtension server1 =
+      new ServerExtension() {
+        @Override
+        protected void configure(ServerBuilder sb) {
+          sb.service("/", (ctx, req) -> HttpResponse.of("hello"));
+        }
+      };
+
+  @RegisterExtension
+  static ServerExtension server2 =
+      new ServerExtension() {
+        @Override
+        protected void configure(ServerBuilder sb) {
+          sb.service("/", (ctx, req) -> createWebClient(server1).execute(req));
+        }
+      };
+
+  private static WebClient createWebClient(ServerExtension server) {
+    return WebClient.builder(server.httpUri()).build();
+  }
+
+  @Test
+  void testHello() throws Exception {
+    // verify that spans are created and context is propagated
+    AggregatedHttpResponse result = createWebClient(server2).get("/").aggregate().get();
+    assertThat(result.contentAscii()).isEqualTo("hello");
+
+    testing.waitAndAssertTraces(
+        trace ->
+            trace.hasSpansSatisfyingExactly(
+                span -> span.hasName("GET").hasKind(SpanKind.CLIENT).hasNoParent(),
+                span -> span.hasName("GET /").hasKind(SpanKind.SERVER).hasParent(trace.getSpan(0)),
+                span -> span.hasName("GET").hasKind(SpanKind.CLIENT).hasParent(trace.getSpan(1)),
+                span ->
+                    span.hasName("GET /").hasKind(SpanKind.SERVER).hasParent(trace.getSpan(2))));
+  }
+}