Change the scope for the netty client callback

Previously the scope was the http client span, which could result in deep nesting.  Now it is the parent span.

Before
[——————Parent—————]
   [ ^ ———Client—————]
                        [ ^—Child—]

Now:
[——————Parent—————]
   [ ^ —Client—] [ ^—Child—]

Also improve the tests.

dd-java-agent/instrumentation/netty-4.0/src/main/java/datadog/trace/instrumentation/netty40/AttributeKeys.java

@@ -16,4 +16,7 @@ public class AttributeKeys {
 
   public static final AttributeKey<Span> CLIENT_ATTRIBUTE_KEY =
       new AttributeKey<>(HttpClientTracingHandler.class.getName() + ".span");
+
+  public static final AttributeKey<Span> CLIENT_PARENT_ATTRIBUTE_KEY =
+      new AttributeKey<>(HttpClientTracingHandler.class.getName() + ".parent");
 }

dd-java-agent/instrumentation/netty-4.0/src/main/java/datadog/trace/instrumentation/netty40/client/HttpClientRequestTracingHandler.java

@@ -10,6 +10,7 @@ import io.netty.channel.ChannelPromise;
 import io.netty.handler.codec.http.HttpRequest;
 import io.opentracing.Scope;
 import io.opentracing.Span;
+import io.opentracing.Tracer;
 import io.opentracing.propagation.Format;
 import io.opentracing.util.GlobalTracer;
 import java.net.InetSocketAddress;
@@ -34,19 +35,19 @@ public class HttpClientRequestTracingHandler extends ChannelOutboundHandlerAdapt
 
     final HttpRequest request = (HttpRequest) msg;
 
-    final Span span = GlobalTracer.get().buildSpan("netty.client.request").start();
+    final Tracer tracer = GlobalTracer.get();
-    try (final Scope scope = GlobalTracer.get().scopeManager().activate(span, false)) {
+    ctx.channel().attr(AttributeKeys.CLIENT_PARENT_ATTRIBUTE_KEY).set(tracer.activeSpan());
+
+    final Span span = tracer.buildSpan("netty.client.request").start();
+    try (final Scope scope = tracer.scopeManager().activate(span, false)) {
       DECORATE.afterStart(span);
       DECORATE.onRequest(span, request);
       DECORATE.onPeerConnection(span, (InetSocketAddress) ctx.channel().remoteAddress());
 
       // AWS calls are often signed, so we can't add headers without breaking the signature.
       if (!request.headers().contains("amz-sdk-invocation-id")) {
-        GlobalTracer.get()
+        tracer.inject(
-            .inject(
+            span.context(), Format.Builtin.HTTP_HEADERS, new NettyResponseInjectAdapter(request));
-                span.context(),
-                Format.Builtin.HTTP_HEADERS,
-                new NettyResponseInjectAdapter(request));
       }
 
       ctx.channel().attr(AttributeKeys.CLIENT_ATTRIBUTE_KEY).set(span);

dd-java-agent/instrumentation/netty-4.0/src/main/java/datadog/trace/instrumentation/netty40/client/HttpClientResponseTracingHandler.java

@@ -9,42 +9,34 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.handler.codec.http.HttpResponse;
 import io.opentracing.Scope;
 import io.opentracing.Span;
-import io.opentracing.tag.Tags;
 import io.opentracing.util.GlobalTracer;
 
 public class HttpClientResponseTracingHandler extends ChannelInboundHandlerAdapter {
 
   @Override
   public void channelRead(final ChannelHandlerContext ctx, final Object msg) {
+    final Span parent = ctx.channel().attr(AttributeKeys.CLIENT_PARENT_ATTRIBUTE_KEY).get();
     final Span span = ctx.channel().attr(AttributeKeys.CLIENT_ATTRIBUTE_KEY).get();
-    if (span == null) {
-      ctx.fireChannelRead(msg);
-      return;
-    }
 
-    try (final Scope scope = GlobalTracer.get().scopeManager().activate(span, false)) {
     final boolean finishSpan = msg instanceof HttpResponse;
 
+    if (span != null && finishSpan) {
+      try (final Scope scope = GlobalTracer.get().scopeManager().activate(span, true)) {
+        DECORATE.onResponse(span, (HttpResponse) msg);
+        DECORATE.beforeFinish(span);
+      }
+    }
+
+    // We want the callback in the scope of the parent, not the client span
+    if (parent != null) {
+      try (final Scope scope = GlobalTracer.get().scopeManager().activate(parent, false)) {
         if (scope instanceof TraceScope) {
           ((TraceScope) scope).setAsyncPropagation(true);
         }
-      try {
         ctx.fireChannelRead(msg);
-      } catch (final Throwable throwable) {
-        if (finishSpan) {
-          DECORATE.onError(span, throwable);
-          DECORATE.beforeFinish(span);
-          Tags.HTTP_STATUS.set(span, 500);
-          span.finish(); // Finish the span manually since finishSpanOnClose was false
-          throw throwable;
-        }
-      }
-
-      if (finishSpan) {
-        DECORATE.onResponse(span, (HttpResponse) msg);
-        DECORATE.beforeFinish(span);
-        span.finish(); // Finish the span manually since finishSpanOnClose was false
       }
+    } else {
+      ctx.fireChannelRead(msg);
     }
   }
 }

dd-java-agent/instrumentation/netty-4.0/src/test/groovy/Netty40ClientTest.groovy

@@ -1,8 +1,10 @@
 import datadog.trace.agent.test.base.HttpClientTest
 import datadog.trace.instrumentation.netty40.client.NettyHttpClientDecorator
 import io.opentracing.tag.Tags
+import org.asynchttpclient.AsyncCompletionHandler
 import org.asynchttpclient.AsyncHttpClient
 import org.asynchttpclient.DefaultAsyncHttpClientConfig
+import org.asynchttpclient.Response
 import spock.lang.Shared
 
 import java.util.concurrent.ExecutionException
@@ -25,8 +27,13 @@ class Netty40ClientTest extends HttpClientTest<NettyHttpClientDecorator> {
     def methodName = "prepare" + method.toLowerCase().capitalize()
     def requestBuilder = asyncHttpClient."$methodName"(uri.toString())
     headers.each { requestBuilder.setHeader(it.key, it.value) }
-    def response = requestBuilder.execute().get()
+    def response = requestBuilder.execute(new AsyncCompletionHandler() {
+      @Override
+      Object onCompleted(Response response) throws Exception {
         callback?.call()
+        return response
+      }
+    }).get()
     return response.statusCode
   }
 
@@ -66,7 +73,7 @@ class Netty40ClientTest extends HttpClientTest<NettyHttpClientDecorator> {
     and:
     assertTraces(1) {
       trace(0, 2) {
-        basicSpan(it, 0, "parent", thrownException)
+        basicSpan(it, 0, "parent", null, thrownException)
 
         span(1) {
           operationName "netty.connect"

dd-java-agent/instrumentation/netty-4.1/src/main/java/datadog/trace/instrumentation/netty41/AttributeKeys.java

@@ -20,4 +20,7 @@ public class AttributeKeys {
 
   public static final AttributeKey<Span> CLIENT_ATTRIBUTE_KEY =
       AttributeKey.valueOf(HttpClientTracingHandler.class.getName() + ".span");
+
+  public static final AttributeKey<Span> CLIENT_PARENT_ATTRIBUTE_KEY =
+      AttributeKey.valueOf(HttpClientTracingHandler.class.getName() + ".parent");
 }

dd-java-agent/instrumentation/netty-4.1/src/main/java/datadog/trace/instrumentation/netty41/client/HttpClientRequestTracingHandler.java

@@ -10,6 +10,7 @@ import io.netty.channel.ChannelPromise;
 import io.netty.handler.codec.http.HttpRequest;
 import io.opentracing.Scope;
 import io.opentracing.Span;
+import io.opentracing.Tracer;
 import io.opentracing.propagation.Format;
 import io.opentracing.util.GlobalTracer;
 import java.net.InetSocketAddress;
@@ -34,19 +35,19 @@ public class HttpClientRequestTracingHandler extends ChannelOutboundHandlerAdapt
 
     final HttpRequest request = (HttpRequest) msg;
 
-    final Span span = GlobalTracer.get().buildSpan("netty.client.request").start();
+    final Tracer tracer = GlobalTracer.get();
-    try (final Scope scope = GlobalTracer.get().scopeManager().activate(span, false)) {
+    ctx.channel().attr(AttributeKeys.CLIENT_PARENT_ATTRIBUTE_KEY).set(tracer.activeSpan());
+
+    final Span span = tracer.buildSpan("netty.client.request").start();
+    try (final Scope scope = tracer.scopeManager().activate(span, false)) {
       DECORATE.afterStart(span);
       DECORATE.onRequest(span, request);
       DECORATE.onPeerConnection(span, (InetSocketAddress) ctx.channel().remoteAddress());
 
       // AWS calls are often signed, so we can't add headers without breaking the signature.
       if (!request.headers().contains("amz-sdk-invocation-id")) {
-        GlobalTracer.get()
+        tracer.inject(
-            .inject(
+            span.context(), Format.Builtin.HTTP_HEADERS, new NettyResponseInjectAdapter(request));
-                span.context(),
-                Format.Builtin.HTTP_HEADERS,
-                new NettyResponseInjectAdapter(request));
       }
 
       ctx.channel().attr(AttributeKeys.CLIENT_ATTRIBUTE_KEY).set(span);

dd-java-agent/instrumentation/netty-4.1/src/main/java/datadog/trace/instrumentation/netty41/client/HttpClientResponseTracingHandler.java

@@ -9,42 +9,34 @@ import io.netty.channel.ChannelInboundHandlerAdapter;
 import io.netty.handler.codec.http.HttpResponse;
 import io.opentracing.Scope;
 import io.opentracing.Span;
-import io.opentracing.tag.Tags;
 import io.opentracing.util.GlobalTracer;
 
 public class HttpClientResponseTracingHandler extends ChannelInboundHandlerAdapter {
 
   @Override
   public void channelRead(final ChannelHandlerContext ctx, final Object msg) {
+    final Span parent = ctx.channel().attr(AttributeKeys.CLIENT_PARENT_ATTRIBUTE_KEY).get();
     final Span span = ctx.channel().attr(AttributeKeys.CLIENT_ATTRIBUTE_KEY).get();
-    if (span == null) {
-      ctx.fireChannelRead(msg);
-      return;
-    }
 
-    try (final Scope scope = GlobalTracer.get().scopeManager().activate(span, false)) {
     final boolean finishSpan = msg instanceof HttpResponse;
 
+    if (span != null && finishSpan) {
+      try (final Scope scope = GlobalTracer.get().scopeManager().activate(span, true)) {
+        DECORATE.onResponse(span, (HttpResponse) msg);
+        DECORATE.beforeFinish(span);
+      }
+    }
+
+    // We want the callback in the scope of the parent, not the client span
+    if (parent != null) {
+      try (final Scope scope = GlobalTracer.get().scopeManager().activate(parent, false)) {
         if (scope instanceof TraceScope) {
           ((TraceScope) scope).setAsyncPropagation(true);
         }
-      try {
         ctx.fireChannelRead(msg);
-      } catch (final Throwable throwable) {
-        if (finishSpan) {
-          DECORATE.onError(span, throwable);
-          DECORATE.beforeFinish(span);
-          Tags.HTTP_STATUS.set(span, 500);
-          span.finish(); // Finish the span manually since finishSpanOnClose was false
-          throw throwable;
-        }
-      }
-
-      if (finishSpan) {
-        DECORATE.onResponse(span, (HttpResponse) msg);
-        DECORATE.beforeFinish(span);
-        span.finish(); // Finish the span manually since finishSpanOnClose was false
       }
+    } else {
+      ctx.fireChannelRead(msg);
     }
   }
 }

dd-java-agent/instrumentation/netty-4.1/src/test/groovy/Netty41ClientTest.groovy

@@ -9,8 +9,10 @@ import io.netty.channel.ChannelInitializer
 import io.netty.channel.embedded.EmbeddedChannel
 import io.netty.handler.codec.http.HttpClientCodec
 import io.opentracing.tag.Tags
+import org.asynchttpclient.AsyncCompletionHandler
 import org.asynchttpclient.AsyncHttpClient
 import org.asynchttpclient.DefaultAsyncHttpClientConfig
+import org.asynchttpclient.Response
 import spock.lang.Shared
 
 import java.util.concurrent.ExecutionException
@@ -33,8 +35,13 @@ class Netty41ClientTest extends HttpClientTest<NettyHttpClientDecorator> {
     def methodName = "prepare" + method.toLowerCase().capitalize()
     def requestBuilder = asyncHttpClient."$methodName"(uri.toString())
     headers.each { requestBuilder.setHeader(it.key, it.value) }
-    def response = requestBuilder.execute().get()
+    def response = requestBuilder.execute(new AsyncCompletionHandler() {
+      @Override
+      Object onCompleted(Response response) throws Exception {
         callback?.call()
+        return response
+      }
+    }).get()
     return response.statusCode
   }
 
@@ -75,7 +82,7 @@ class Netty41ClientTest extends HttpClientTest<NettyHttpClientDecorator> {
     and:
     assertTraces(1) {
       trace(0, 2) {
-        basicSpan(it, 0, "parent", thrownException)
+        basicSpan(it, 0, "parent", null, thrownException)
 
         span(1) {
           operationName "netty.connect"

dd-java-agent/instrumentation/ratpack-1.4/src/test/groovy/RatpackTest.groovy

@@ -429,7 +429,7 @@ class RatpackTest extends AgentTestRunner {
           serviceName "unnamed-java-app"
           operationName "netty.client.request"
           spanType DDSpanTypes.HTTP_CLIENT
-          childOf(span(3))
+          childOf(span(1))
           errored false
           tags {
             "$Tags.COMPONENT.key" "netty-client"

dd-java-agent/instrumentation/vertx/src/test/groovy/VertxHttpClientTest.groovy

@@ -1,151 +1,54 @@
-import datadog.trace.agent.test.AgentTestRunner
+import datadog.trace.agent.test.base.HttpClientTest
-import datadog.trace.agent.test.utils.PortUtils
+import datadog.trace.instrumentation.netty41.client.NettyHttpClientDecorator
-import datadog.trace.api.DDSpanTypes
-import io.netty.channel.AbstractChannel
-import io.opentracing.tag.Tags
 import io.vertx.core.Vertx
 import io.vertx.core.VertxOptions
 import io.vertx.core.http.HttpClient
-import io.vertx.core.http.HttpClientRequest
 import io.vertx.core.http.HttpClientResponse
 import io.vertx.core.http.HttpMethod
-import spock.lang.AutoCleanup
 import spock.lang.Shared
+import spock.lang.Timeout
 
 import java.util.concurrent.CompletableFuture
 
-import static datadog.trace.agent.test.server.http.TestHttpServer.httpServer
+@Timeout(10)
-import static datadog.trace.agent.test.utils.TraceUtils.runUnderTrace
+class VertxHttpClientTest extends HttpClientTest<NettyHttpClientDecorator> {
-
-class VertxHttpClientTest extends AgentTestRunner {
-
-  private static final String MESSAGE = "hello world"
-
-  @AutoCleanup
-  @Shared
-  def server = httpServer {
-    handlers {
-      prefix("success") {
-        handleDistributedRequest()
-
-        response.status(200).send(MESSAGE)
-      }
-
-      prefix("error") {
-        handleDistributedRequest()
-
-        throw new RuntimeException("error")
-      }
-    }
-  }
 
   @Shared
   Vertx vertx = Vertx.vertx(new VertxOptions())
   @Shared
   HttpClient httpClient = vertx.createHttpClient()
 
-  def "#route request trace"() {
+  @Override
-    setup:
+  int doRequest(String method, URI uri, Map<String, String> headers, Closure callback) {
-    def responseFuture = new CompletableFuture<HttpClientResponse>()
+    CompletableFuture<HttpClientResponse> future = new CompletableFuture<>()
-    def messageFuture = new CompletableFuture<String>()
+    def request = httpClient.request(HttpMethod.valueOf(method), uri.port, uri.host, "$uri")
-    httpClient.getNow(server.address.port, server.address.host, "/" + route, { response ->
+    headers.each { request.putHeader(it.key, it.value) }
-      responseFuture.complete(response)
+    request.handler { response ->
-      response.bodyHandler({ buffer ->
+      callback?.call()
-        messageFuture.complete(buffer.toString())
+      future.complete(response)
-      })
-    })
-
-    when:
-    HttpClientResponse response = responseFuture.get()
-    String message = messageFuture.get()
-
-    then:
-    response.statusCode() == expectedStatus
-    if (expectedMessage != null) {
-      message == expectedMessage
     }
-
-    assertTraces(2) {
-      server.distributedRequestTrace(it, 0, TEST_WRITER[1][0])
-      trace(1, 1) {
-        span(0) {
-          parent()
-          serviceName "unnamed-java-app"
-          operationName "netty.client.request"
-          resourceName "GET /$route"
-          spanType DDSpanTypes.HTTP_CLIENT
-          errored expectedError
-          tags {
-            defaultTags()
-            "$Tags.HTTP_STATUS.key" expectedStatus
-            "$Tags.HTTP_URL.key" "${server.address}/$route"
-            "$Tags.PEER_HOSTNAME.key" server.address.host
-            "$Tags.PEER_HOST_IPV4.key" "127.0.0.1"
-            "$Tags.PEER_PORT.key" server.address.port
-            "$Tags.HTTP_METHOD.key" "GET"
-            "$Tags.SPAN_KIND.key" Tags.SPAN_KIND_CLIENT
-            "$Tags.COMPONENT.key" "netty-client"
-            if (expectedError) {
-              "$Tags.ERROR.key" true
-            }
-          }
-        }
-      }
-    }
-
-    where:
-    route     | expectedStatus | expectedError | expectedMessage
-    "success" | 200            | false         | MESSAGE
-    "error"   | 500            | true          | null
-  }
-
-  def "test connection failure"() {
-    setup:
-    def invalidPort = PortUtils.randomOpenPort()
-
-    def errorFuture = new CompletableFuture<Throwable>()
-
-    runUnderTrace("parent") {
-      HttpClientRequest request = httpClient.request(
-        HttpMethod.GET,
-        invalidPort,
-        server.address.host,
-        "/",
-        { response ->
-          // We expect to never get here since our request is expected to fail
-          errorFuture.complete(null)
-        })
-      request.exceptionHandler({ error ->
-        errorFuture.complete(error)
-      })
     request.end()
+
+    return future.get().statusCode()
   }
 
-    when:
+  @Override
-    def throwable = errorFuture.get()
+  NettyHttpClientDecorator decorator() {
+    return NettyHttpClientDecorator.DECORATE
+  }
 
-    then:
+  @Override
-    throwable.cause instanceof ConnectException
+  String expectedOperationName() {
+    return "netty.client.request"
+  }
 
-    and:
+  @Override
-    assertTraces(1) {
+  boolean testRedirects() {
-      trace(0, 2) {
+    false
-        span(0) {
-          operationName "parent"
-          parent()
-        }
-        span(1) {
-          operationName "netty.connect"
-          resourceName "netty.connect"
-          childOf span(0)
-          errored true
-          tags {
-            "$Tags.COMPONENT.key" "netty"
-            errorTags AbstractChannel.AnnotatedConnectException, "Connection refused: localhost/127.0.0.1:$invalidPort"
-            defaultTags()
-          }
-        }
-      }
   }
+
+  @Override
+  boolean testConnectionFailure() {
+    false
   }
 }

dd-java-agent/instrumentation/vertx/src/test/groovy/VertxServerTest.groovy

@@ -31,7 +31,7 @@ class VertxServerTest extends AgentTestRunner {
   def "test server request/response"() {
     setup:
     def request = new Request.Builder()
-      .url("http://localhost:$port/test")
+      .url("http://localhost:$port/proxy")
       .header("x-datadog-trace-id", "123")
       .header("x-datadog-parent-id", "456")
       .get()
@@ -43,14 +43,13 @@ class VertxServerTest extends AgentTestRunner {
     response.body().string() == "Hello World"
 
     and:
-    assertTraces(1) {
+    assertTraces(2) {
       trace(0, 2) {
         span(0) {
-          traceId "123"
-          parentId "456"
           serviceName "unnamed-java-app"
           operationName "netty.request"
           resourceName "GET /test"
+          childOf(trace(1).get(1))
           spanType DDSpanTypes.HTTP_SERVER
           errored false
           tags {
@@ -70,6 +69,47 @@ class VertxServerTest extends AgentTestRunner {
           assert span(1).operationName.endsWith('.tracedMethod')
         }
       }
+      trace(1, 2) {
+        span(0) {
+          serviceName "unnamed-java-app"
+          operationName "netty.request"
+          resourceName "GET /proxy"
+          traceId "123"
+          parentId "456"
+          spanType DDSpanTypes.HTTP_SERVER
+          errored false
+          tags {
+            "$Tags.COMPONENT.key" "netty"
+            "$Tags.HTTP_METHOD.key" "GET"
+            "$Tags.HTTP_STATUS.key" 200
+            "$Tags.HTTP_URL.key" "http://localhost:$port/proxy"
+            "$Tags.PEER_HOSTNAME.key" "localhost"
+            "$Tags.PEER_HOST_IPV4.key" "127.0.0.1"
+            "$Tags.PEER_PORT.key" Integer
+            "$Tags.SPAN_KIND.key" Tags.SPAN_KIND_SERVER
+            defaultTags(true)
+          }
+        }
+        span(1) {
+          serviceName "unnamed-java-app"
+          operationName "netty.client.request"
+          resourceName "GET /test"
+          childOf(span(0))
+          spanType DDSpanTypes.HTTP_CLIENT
+          errored false
+          tags {
+            "$Tags.COMPONENT.key" "netty-client"
+            "$Tags.HTTP_METHOD.key" "GET"
+            "$Tags.HTTP_STATUS.key" 200
+            "$Tags.HTTP_URL.key" "http://localhost:$port/test"
+            "$Tags.PEER_HOSTNAME.key" "localhost"
+            "$Tags.PEER_HOST_IPV4.key" "127.0.0.1"
+            "$Tags.PEER_PORT.key" Integer
+            "$Tags.SPAN_KIND.key" Tags.SPAN_KIND_CLIENT
+            defaultTags()
+          }
+        }
+      }
     }
   }
 

dd-java-agent/instrumentation/vertx/src/test/java/VertxWebTestServer.java

@@ -1,25 +1,36 @@
 import datadog.trace.api.Trace;
 import io.vertx.core.AbstractVerticle;
+import io.vertx.core.DeploymentOptions;
 import io.vertx.core.Future;
 import io.vertx.core.Vertx;
 import io.vertx.core.VertxOptions;
+import io.vertx.core.buffer.Buffer;
+import io.vertx.core.http.HttpClient;
+import io.vertx.core.json.JsonObject;
 import io.vertx.ext.web.Router;
+import io.vertx.ext.web.RoutingContext;
+import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 
 public class VertxWebTestServer extends AbstractVerticle {
+  public static final String CONFIG_HTTP_SERVER_PORT = "http.server.port";
 
   public static Vertx start(final int port) throws ExecutionException, InterruptedException {
     /* This is highly against Vertx ideas, but our tests are synchronous
     so we have to make sure server is up and running */
     final CompletableFuture<Void> future = new CompletableFuture<>();
 
-    final Vertx vertx = Vertx.vertx(new VertxOptions());
+    final Vertx vertx = Vertx.vertx(new VertxOptions().setClusterPort(port));
+
     vertx.deployVerticle(
-        new VertxWebTestServer(port),
+        VertxWebTestServer.class.getName(),
+        new DeploymentOptions()
+            .setConfig(new JsonObject().put(CONFIG_HTTP_SERVER_PORT, port))
+            .setInstances(3),
         res -> {
           if (!res.succeeded()) {
-            throw new RuntimeException("Cannot deploy server Verticle");
+            throw new RuntimeException("Cannot deploy server Verticle", res.cause());
           }
           future.complete(null);
         });
@@ -29,14 +40,12 @@ public class VertxWebTestServer extends AbstractVerticle {
     return vertx;
   }
 
-  private final int port;
-
-  public VertxWebTestServer(final int port) {
-    this.port = port;
-  }
-
   @Override
   public void start(final Future<Void> startFuture) {
+    final HttpClient client = vertx.createHttpClient();
+
+    final int port = config().getInteger(CONFIG_HTTP_SERVER_PORT);
+
     final Router router = Router.router(vertx);
 
     router
@@ -51,6 +60,26 @@ public class VertxWebTestServer extends AbstractVerticle {
             routingContext -> {
               routingContext.response().setStatusCode(500).end();
             });
+    router
+        .route("/proxy")
+        .handler(
+            routingContext -> {
+              client
+                  .get(
+                      port,
+                      "localhost",
+                      "/test",
+                      response -> {
+                        response.bodyHandler(
+                            buffer -> {
+                              routingContext
+                                  .response()
+                                  .setStatusCode(response.statusCode())
+                                  .end(buffer);
+                            });
+                      })
+                  .end(Optional.ofNullable(routingContext.getBody()).orElse(Buffer.buffer()));
+            });
     router
         .route("/test")
         .handler(
@@ -58,10 +87,7 @@ public class VertxWebTestServer extends AbstractVerticle {
               tracedMethod();
               routingContext.next();
             })
-        .blockingHandler(
+        .blockingHandler(RoutingContext::next)
-            routingContext -> {
-              routingContext.next();
-            })
         .handler(
             routingContext -> {
               routingContext.response().putHeader("content-type", "text/html").end("Hello World");
@@ -74,5 +100,5 @@ public class VertxWebTestServer extends AbstractVerticle {
   }
 
   @Trace
-  public void tracedMethod() {}
+  private void tracedMethod() {}
 }

dd-java-agent/instrumentation/vertx/vertx.gradle

@@ -42,9 +42,11 @@ dependencies {
   implementation deps.autoservice
 
   testCompile project(':dd-java-agent:testing')
+  testCompile project(':dd-java-agent:instrumentation:netty-4.1')
   testCompile project(':dd-java-agent:instrumentation:java-concurrent')
   testCompile project(':dd-java-agent:instrumentation:trace-annotation')
-  testCompile project(':dd-java-agent:instrumentation:netty-4.1')
+
+  // Tests seem to fail before 3.5... maybe a problem with some of the tests?
   testCompile group: 'io.vertx', name: 'vertx-web', version: '3.5.0'
 
   latestDepTestCompile group: 'io.vertx', name: 'vertx-web', version: '+'

dd-java-agent/testing/src/main/groovy/datadog/trace/agent/test/base/HttpClientTest.groovy

@@ -176,10 +176,7 @@ abstract class HttpClientTest<T extends HttpClientDecorator> extends AgentTestRu
     assertTraces(1) {
       trace(0, size(3)) {
         basicSpan(it, 0, "parent")
-        span(1) {
+        basicSpan(it, 1, "child", span(0))
-          operationName "child"
-          childOf span(0)
-        }
         clientSpan(it, 2, span(0), method, false)
       }
     }
@@ -205,10 +202,7 @@ abstract class HttpClientTest<T extends HttpClientDecorator> extends AgentTestRu
         clientSpan(it, 0, null, method, false)
       }
       trace(1, 1) {
-        span(0) {
+        basicSpan(it, 0, "child")
-          operationName "child"
-          parent()
-        }
       }
     }
 
@@ -306,7 +300,7 @@ abstract class HttpClientTest<T extends HttpClientDecorator> extends AgentTestRu
     and:
     assertTraces(1) {
       trace(0, 2) {
-        basicSpan(it, 0, "parent", thrownException)
+        basicSpan(it, 0, "parent", null, thrownException)
         clientSpan(it, 1, span(0), method, false, false, uri, null, thrownException)
       }
     }

dd-java-agent/testing/src/main/groovy/datadog/trace/agent/test/utils/TraceUtils.groovy

@@ -1,5 +1,6 @@
 package datadog.trace.agent.test.utils
 
+import datadog.opentracing.DDSpan
 import datadog.trace.agent.decorator.BaseDecorator
 import datadog.trace.agent.test.asserts.TraceAssert
 import datadog.trace.context.TraceScope
@@ -42,9 +43,13 @@ class TraceUtils {
     }
   }
 
-  static basicSpan(TraceAssert trace, int index, String spanName, Throwable exception = null) {
+  static basicSpan(TraceAssert trace, int index, String spanName, Object parentSpan = null, Throwable exception = null) {
     trace.span(index) {
+      if (parentSpan == null) {
         parent()
+      } else {
+        childOf((DDSpan) parentSpan)
+      }
       serviceName "unnamed-java-app"
       operationName spanName
       resourceName spanName