First attempt to add GRPC instrumentation (#1139)

* Adding preliminary GRPC instrumentation to Sleuth

fixes #305

docs/src/main/asciidoc/spring-cloud-sleuth.adoc

@@ -1210,6 +1210,44 @@ You can disable it by setting `spring.sleuth.feign.processor.enabled` to `false`
 If you set it to `false`, Spring Cloud Sleuth does not instrument any of your custom Feign components.
 However, all the default instrumentation is still there.
 
+=== gRPC
+
+Spring Cloud Sleuth provides instrumentation for https://grpc.io/[gRPC] through `TraceGrpcAutoConfiguration`. You can disable it entirely by setting `spring.sleuth.grpc.enabled` to `false`.
+
+==== Dependencies
+IMPORTANT: The gRPC integration relies on two external libraries to instrument clients and servers and both of those libraries must be on the class path to enable the instrumentation.
+
+Maven: 
+```
+		<dependency>
+			<groupId>io.github.lognet</groupId>
+			<artifactId>grpc-spring-boot-starter</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>io.zipkin.brave</groupId>
+			<artifactId>brave-instrumentation-grpc</artifactId>
+		</dependency>
+```
+Gradle:
+```
+    compile("io.github.lognet:grpc-spring-boot-starter")
+    compile("io.zipkin.brave:brave-instrumentation-grpc")
+```
+
+==== Server Instrumentation
+
+Spring Cloud Sleuth leverages grpc-spring-boot-starter to register Brave's gRPC server interceptor with all services annotated with `@GRpcService`. 
+
+==== Client Instrumentation
+
+gRPC clients leverage a `ManagedChannelBuilder` to construct a `ManagedChannel` used to communicate to the gRPC server. The native `ManagedChannelBuilder` provides static methods as entry points for construction of `ManagedChannel` instances, however, this mechanism is outside the influence of the Spring application context.
+
+IMPORTANT: Spring Cloud Sleuth provides a `SpringAwareManagedChannelBuilder` that can be customized through the Spring application context and injected by gRPC clients. *This builder must be used when creating `ManagedChannel` instances.*
+
+
+Sleuth creates a `TracingManagedChannelBuilderCustomizer` which inject Brave's client interceptor into the `SpringAwareManagedChannelBuilder`.
+
+
 === Asynchronous Communication
 
 ==== `@Async` Annotated methods

spring-cloud-sleuth-core/pom.xml

@@ -233,6 +233,17 @@
 			<artifactId>spring-jms</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<!-- GRPC Optional Dependencies -->
+		<dependency>
+			<groupId>io.github.lognet</groupId>
+			<artifactId>grpc-spring-boot-starter</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>io.zipkin.brave</groupId>
+			<artifactId>brave-instrumentation-grpc</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-autoconfigure-processor</artifactId>
@@ -311,6 +322,13 @@
 			<artifactId>activemq-ra</artifactId>
 			<scope>test</scope>
 		</dependency>
+		<!-- This forces the guava version to 20 within the test scope, which is required by GRPC -->
+		<dependency>
+		    <groupId>com.google.guava</groupId>
+		    <artifactId>guava</artifactId>
+		    <version>20.0</version>
+		    <scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<profiles>

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/grpc/GrpcManagedChannelBuilderCustomizer.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth.instrument.grpc;
+
+import io.grpc.ManagedChannelBuilder;
+
+/**
+ * Callback interface that can be implemented by beans wishing to further customize the
+ * {@link io.grpc.ManagedChannelBuilder} via the {@link SpringAwareManagedChannelBuilder}.
+ *
+ * @author tyler.vangorder
+ */
+public interface GrpcManagedChannelBuilderCustomizer {
+
+	void customize(ManagedChannelBuilder<?> managedChannelBuilder);
+
+}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/grpc/SpringAwareManagedChannelBuilder.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2013-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth.instrument.grpc;
+
+import java.util.List;
+import java.util.Optional;
+
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.inprocess.InProcessChannelBuilder;
+
+/**
+ * This is a Spring-aware managed channel builder that wraps the static entry points of
+ * gRPC's ManagedChannelBuilder to allow the configuration of the builder to be influenced
+ * by the Spring Context. All GrpcManagedChannelBuilderCustomizer instances included in
+ * the application context will have the opportunity to customize the builder.
+ *
+ * NOTE: There is nothing "Sleuth-specific" about this, however, there is currently not a
+ * good spring abstraction for client-side gRPC. Ideally, this could be moved up into
+ * grpc-spring-boot-starter or a new project could be created
+ * "spring-grpc"/"spring-cloud-grpc"?
+ *
+ * @author tyler.vangorder
+ */
+public class SpringAwareManagedChannelBuilder {
+
+	private List<GrpcManagedChannelBuilderCustomizer> customizers;
+
+	public SpringAwareManagedChannelBuilder(
+			Optional<List<GrpcManagedChannelBuilderCustomizer>> customizers) {
+		this.customizers = customizers.orElse(null);
+	}
+
+	public ManagedChannelBuilder<?> forAddress(String name, int port) {
+
+		ManagedChannelBuilder<?> builder = ManagedChannelBuilder.forAddress(name, port);
+
+		if (this.customizers != null) {
+			this.customizers.stream()
+					.forEach(customizer -> customizer.customize(builder));
+		}
+		return builder;
+	}
+
+	public ManagedChannelBuilder<?> forTarget(String target) {
+		ManagedChannelBuilder<?> builder = ManagedChannelBuilder.forTarget(target);
+		if (this.customizers != null) {
+			this.customizers.stream()
+					.forEach(customizer -> customizer.customize(builder));
+		}
+		return builder;
+	}
+
+	public ManagedChannelBuilder<?> inProcessChannelBuilder(String serverName) {
+		ManagedChannelBuilder<?> builder = InProcessChannelBuilder.forName(serverName);
+		if (this.customizers != null) {
+			this.customizers.stream()
+					.forEach(customizer -> customizer.customize(builder));
+		}
+		return builder;
+	}
+
+}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/grpc/TraceGrpcAutoConfiguration.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2013-2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth.instrument.grpc;
+
+import java.util.List;
+import java.util.Optional;
+
+import brave.Tracing;
+import brave.grpc.GrpcTracing;
+import io.grpc.ServerInterceptor;
+import org.lognet.springboot.grpc.GRpcGlobalInterceptor;
+
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.context.annotation.Bean;
+
+/**
+ * {@link org.springframework.boot.autoconfigure.EnableAutoConfiguration
+ * Auto-configuration} enables span information propagation when using GRPC.
+ *
+ * This configuration is only enabled when both grpc-spring-boot-starter and
+ * brave-instrumentation-grpc are on the classpath.
+ *
+ * @author tyler.vangorder
+ */
+@ConditionalOnClass({ GrpcTracing.class, GRpcGlobalInterceptor.class })
+@ConditionalOnProperty(value = "spring.sleuth.grpc.enabled", matchIfMissing = true)
+@ConditionalOnBean(Tracing.class)
+public class TraceGrpcAutoConfiguration {
+
+	@Bean
+	public GrpcTracing grpcTracing(Tracing tracing) {
+		return GrpcTracing.create(tracing);
+	}
+
+	// Register a global interceptor for both the server
+	@Bean
+	@GRpcGlobalInterceptor
+	ServerInterceptor grpcServerBraveInterceptor(GrpcTracing grpcTracing) {
+		return grpcTracing.newServerInterceptor();
+	}
+
+	// This is wrapper around gRPC's managed channel builder that is spring-aware
+	@Bean
+	@ConditionalOnMissingBean(SpringAwareManagedChannelBuilder.class)
+	public SpringAwareManagedChannelBuilder managedChannelBuilder(
+			Optional<List<GrpcManagedChannelBuilderCustomizer>> customizers) {
+		return new SpringAwareManagedChannelBuilder(customizers);
+	}
+
+	@Bean
+	GrpcManagedChannelBuilderCustomizer tracingManagedChannelBuilderCustomizer(
+			GrpcTracing grpcTracing) {
+		return new TracingManagedChannelBuilderCustomizer(grpcTracing);
+	}
+
+}

spring-cloud-sleuth-core/src/main/java/org/springframework/cloud/sleuth/instrument/grpc/TracingManagedChannelBuilderCustomizer.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2018 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.sleuth.instrument.grpc;
+
+import brave.grpc.GrpcTracing;
+import io.grpc.ManagedChannelBuilder;
+
+/**
+ * @author tyler.vangorder
+ */
+public class TracingManagedChannelBuilderCustomizer
+		implements GrpcManagedChannelBuilderCustomizer {
+
+	GrpcTracing grpcTracing;
+
+	public TracingManagedChannelBuilderCustomizer(GrpcTracing grpcTracing) {
+		this.grpcTracing = grpcTracing;
+	}
+
+	/**
+	 * Add brave's client interceptor to the builder.
+	 */
+	@Override
+	public void customize(ManagedChannelBuilder<?> managedChannelBuilder) {
+		managedChannelBuilder.intercept(this.grpcTracing.newClientInterceptor());
+	}
+
+}

spring-cloud-sleuth-core/src/main/resources/META-INF/additional-spring-configuration-metadata.json

@@ -46,5 +46,11 @@
     "type": "java.lang.Boolean",
     "description": "Enable span information propagation when using Zuul.",
     "defaultValue": true
+  }, 
+  {
+    "name": "spring.sleuth.grpc.enabled",
+    "type": "java.lang.Boolean",
+    "description": "Enable span information propagation when using GRPC.",
+    "defaultValue": true
   }
 ]}

spring-cloud-sleuth-core/src/main/resources/META-INF/spring.factories

@@ -18,6 +18,7 @@ org.springframework.cloud.sleuth.instrument.rxjava.RxJavaAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.reactor.TraceReactorAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.web.TraceWebFluxAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.zuul.TraceZuulAutoConfiguration,\
+org.springframework.cloud.sleuth.instrument.grpc.TraceGrpcAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.messaging.TraceMessagingAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.messaging.TraceSpringIntegrationAutoConfiguration,\
 org.springframework.cloud.sleuth.instrument.messaging.websocket.TraceWebSocketAutoConfiguration,\