feat: add federated tracing instrumentation

README.md

@@ -12,7 +12,7 @@ An example of [graphql-spring-boot](https://www.graphql-java-kickstart.com/sprin
 
 ## Getting started
 
-### Dependency management
+### Dependency management with Gradle
 
 Make sure JCenter is among your repositories:
 
@@ -56,3 +56,34 @@ you will also need to provide:
 
 A minimal but complete example is available in
 [InventorySchemaProvider](spring-example/src/main/java/com/apollographql/federation/springexample/InventorySchemaProvider.java).
+
+### Federated tracing
+
+To make your server generate performance traces and return them along with
+responses to the Apollo Gateway (which then can send them to Apollo Graph
+Manager), install the `FederatedTracingInstrumentation` into your `GraphQL`
+object:
+
+```java
+GraphQL graphql = GraphQL.newGraphQL(graphQLSchema)
+  .instrumentation(new FederatedTracingInstrumentation())
+  .build()
+```
+
+It is generally desired to only create traces for requests that actually come
+from Apollo Gateway, as they aren't helpful if you're connecting directly to
+your backend service for testing. In order for `FederatedTracingInstrumentation`
+to know if the request is coming from Gateway, you need to give it access to the
+HTTP request's headers, by making the `context` part of your `ExecutionInput`
+implement the `HTTPRequestHeaders` interface.  For example:
+
+```java
+    HTTPRequestHeaders context = new HTTPRequestHeaders() {
+        @Override
+        public @Nullable String getHTTPRequestHeader(String caseInsensitiveHeaderName) {
+            return myIncomingHTTPRequest.getHeader(caseInsensitiveHeaderName);
+        }
+    }
+    graphql.execute(ExecutionInput.newExecutionInput(queryString).context(context));
+
+```

graphql-java-support/pom.xml

@@ -30,9 +30,21 @@
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-engine</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java</artifactId>
+            <version>3.9.0</version>
+        </dependency>
     </dependencies>
 
     <build>
+        <extensions>
+            <extension>
+                <groupId>kr.motd.maven</groupId>
+                <artifactId>os-maven-plugin</artifactId>
+                <version>1.6.0</version>
+            </extension>
+        </extensions>
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
@@ -54,6 +66,23 @@
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>cobertura-maven-plugin</artifactId>
             </plugin>
+
+            <plugin>
+                <groupId>org.xolstice.maven.plugins</groupId>
+                <artifactId>protobuf-maven-plugin</artifactId>
+                <version>0.6.1</version>
+                <configuration>
+                    <protocArtifact>com.google.protobuf:protoc:3.9.0:exe:${os.detected.classifier}</protocArtifact>
+                </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>compile</goal>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
         </plugins>
     </build>
 </project>