Adds Spring Boot 1.5 (webmvc4) example (#25)

README.md

@@ -30,6 +30,8 @@ Next, you can view traces that went through the backend via http://localhost:941
 * This is a locally run zipkin service which keeps traces in memory
 
 ## Starting the Services
+
+### Servlet Container Option
 In a separate tab or window, start each of [brave.webmvc.Frontend](/webmvc4/src/main/java/brave/webmvc/Frontend.java)
 and [brave.webmvc.Backend](/webmvc4/src/main/java/brave/webmvc/Backend.java):
 ```bash
@@ -39,6 +41,15 @@ $ mvn jetty:run -Pfrontend
 $ mvn jetty:run -Pbackend
 ```
 
+### Spring Boot Option
+In a separate tab or window, start each of [brave.webmvc.Frontend](/webmvc4-boot/src/main/java/brave/webmvc/Frontend.java)
+and [brave.webmvc.Backend](/webmvc4-boot/src/main/java/brave/webmvc/Backend.java):
+```bash
+$ cd webmvc4-boot
+$ mvn compile exec:java -Dexec.mainClass=brave.webmvc.Backend
+$ mvn compile exec:java -Dexec.mainClass=brave.webmvc.Frontend
+```
+
 Next, run [Zipkin](http://zipkin.io/), which stores and queries traces
 reported by the above services.
 

webmvc4-boot/README.md

@@ -0,0 +1,18 @@
+## WebMVC 4 Boot Example
+
+Instead of servlet, this uses Spring Boot 1.5 to create a self-contained
+application that runs Spring WebMVC 4 controllers.
+
+*   brave.webmvc.Frontend and Backend : Rest controllers with no tracing configuration
+*   brave.webmvc.TracingConfiguration : This adds tracing by configuring the tracer, server and client tracing interceptors.
+
+`TracingConfiguration` is automatically loaded due to `META-INF/spring.factories`
+This allows the `Frontend` and `Backend` controllers to have no tracing
+code. Inside the tracing configuration, you'll notice the rest template
+is setup via a `RestTemplateCustomizer`, which ensures application-level
+interceptors are not affected. Also, you'll notice layered tracing for
+server requests. First, `TracingFilter` creates a span, then later,
+`SpanCustomizingAsyncHandlerInterceptor` adds MVC tags to it.
+
+*Note* This only lightly configures tracing. When doing anything serious,
+consider [Spring Cloud Sleuth](https://github.com/spring-cloud/spring-cloud-sleuth) instead.

webmvc4-boot/pom.xml

@@ -0,0 +1,69 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>io.zipkin.brave</groupId>
+  <artifactId>brave-webmvc4-boot-example</artifactId>
+  <version>1.0-SNAPSHOT</version>
+  <packaging>jar</packaging>
+
+  <name>brave-webmvc4-boot-example</name>
+  <description>Example using Brave to trace RPCs from Spring Web MVC</description>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>1.7</maven.compiler.source>
+    <maven.compiler.target>1.7</maven.compiler.target>
+
+    <spring-boot.version>1.5.14.RELEASE</spring-boot.version>
+    <brave.version>5.1.3</brave.version>
+  </properties>
+
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>org.springframework.boot</groupId>
+        <artifactId>spring-boot-dependencies</artifactId>
+        <version>${spring-boot.version}</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+      <dependency>
+        <groupId>io.zipkin.brave</groupId>
+        <artifactId>brave-bom</artifactId>
+        <version>${brave.version}</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.springframework.boot</groupId>
+      <artifactId>spring-boot-starter-web</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>io.zipkin.brave</groupId>
+      <artifactId>brave</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.zipkin.reporter2</groupId>
+      <artifactId>zipkin-sender-okhttp3</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.zipkin.brave</groupId>
+      <artifactId>brave-context-slf4j</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.zipkin.brave</groupId>
+      <artifactId>brave-instrumentation-spring-web</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.zipkin.brave</groupId>
+      <artifactId>brave-instrumentation-spring-webmvc</artifactId>
+    </dependency>
+  </dependencies>
+</project>

webmvc4-boot/src/main/java/brave/webmvc/Backend.java

@@ -0,0 +1,28 @@
+package brave.webmvc;
+
+import java.util.Date;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@EnableAutoConfiguration
+@RestController
+public class Backend {
+
+  @RequestMapping("/api")
+  public String printDate(@RequestHeader(name = "user-name", required = false) String username) {
+    if (username != null) {
+      return new Date().toString() + " " + username;
+    }
+    return new Date().toString();
+  }
+
+  public static void main(String[] args) {
+    SpringApplication.run(Backend.class,
+        "--spring.application.name=backend",
+        "--server.port=9000"
+    );
+  }
+}

webmvc4-boot/src/main/java/brave/webmvc/Frontend.java

@@ -0,0 +1,33 @@
+package brave.webmvc;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.Bean;
+import org.springframework.web.bind.annotation.CrossOrigin;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.client.RestTemplate;
+
+@EnableAutoConfiguration
+@RestController
+@CrossOrigin // So that javascript can be hosted elsewhere
+public class Frontend {
+
+  @Autowired RestTemplate restTemplate;
+
+  @RequestMapping("/") public String callBackend() {
+    return restTemplate.getForObject("http://localhost:9000/api", String.class);
+  }
+
+  @Bean RestTemplate restTemplate() {
+    return new RestTemplate();
+  }
+
+  public static void main(String[] args) {
+    SpringApplication.run(Frontend.class,
+        "--spring.application.name=frontend",
+        "--server.port=8081"
+    );
+  }
+}

webmvc4-boot/src/main/java/brave/webmvc/TracingConfiguration.java

@@ -0,0 +1,86 @@
+package brave.webmvc;
+
+import brave.Tracing;
+import brave.context.slf4j.MDCCurrentTraceContext;
+import brave.http.HttpTracing;
+import brave.propagation.B3Propagation;
+import brave.propagation.ExtraFieldPropagation;
+import brave.servlet.TracingFilter;
+import brave.spring.web.TracingClientHttpRequestInterceptor;
+import brave.spring.webmvc.SpanCustomizingAsyncHandlerInterceptor;
+import java.util.ArrayList;
+import java.util.List;
+import javax.servlet.Filter;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.web.client.RestTemplateCustomizer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
+import org.springframework.http.client.ClientHttpRequestInterceptor;
+import org.springframework.web.client.RestTemplate;
+import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
+import zipkin2.Span;
+import zipkin2.reporter.AsyncReporter;
+import zipkin2.reporter.Sender;
+import zipkin2.reporter.okhttp3.OkHttpSender;
+
+/**
+ * This adds tracing configuration to any web mvc controllers or rest template clients.
+ */
+@Configuration
+// Importing a class is effectively the same as declaring bean methods
+@Import(SpanCustomizingAsyncHandlerInterceptor.class)
+public class TracingConfiguration extends WebMvcConfigurerAdapter {
+
+  /** Configuration for how to send spans to Zipkin */
+  @Bean Sender sender() {
+    return OkHttpSender.create("http://127.0.0.1:9411/api/v2/spans");
+  }
+
+  /** Configuration for how to buffer spans into messages for Zipkin */
+  @Bean AsyncReporter<Span> spanReporter() {
+    return AsyncReporter.create(sender());
+  }
+
+  /** Controls aspects of tracing such as the name that shows up in the UI */
+  @Bean Tracing tracing(@Value("${spring.application.name}") String serviceName) {
+    return Tracing.newBuilder()
+        .localServiceName(serviceName)
+        .propagationFactory(ExtraFieldPropagation.newFactory(B3Propagation.FACTORY, "user-name"))
+        .currentTraceContext(MDCCurrentTraceContext.create()) // puts trace IDs into logs
+        .spanReporter(spanReporter()).build();
+  }
+
+  /** decides how to name and tag spans. By default they are named the same as the http method. */
+  @Bean HttpTracing httpTracing(Tracing tracing) {
+    return HttpTracing.create(tracing);
+  }
+
+  /** Creates client spans for http requests */
+  @Bean @Order(Ordered.HIGHEST_PRECEDENCE)
+  RestTemplateCustomizer tracingRestTemplateCustomizer(final HttpTracing httpTracing) {
+    return new RestTemplateCustomizer() {
+      @Override public void customize(RestTemplate restTemplate) {
+        List<ClientHttpRequestInterceptor> interceptors =
+            new ArrayList<>(restTemplate.getInterceptors());
+        interceptors.add(0, TracingClientHttpRequestInterceptor.create(httpTracing));
+      }
+    };
+  }
+
+  /** Creates server spans for http requests */
+  @Bean Filter tracingFilter(HttpTracing httpTracing) {
+    return TracingFilter.create(httpTracing);
+  }
+
+  @Autowired SpanCustomizingAsyncHandlerInterceptor webMvcTracingCustomizer;
+
+  /** Decorates server spans with application-defined web tags */
+  @Override public void addInterceptors(InterceptorRegistry registry) {
+    registry.addInterceptor(webMvcTracingCustomizer);
+  }
+}

webmvc4-boot/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
+brave.webmvc.TracingConfiguration

webmvc4-boot/src/main/resources/application.properties

@@ -0,0 +1,5 @@
+# spring.application.name and server.port are set in the main methods,
+# so not done here
+logging.level.org.springframework.web=DEBUG
+# Adds trace and span IDs to logs (when a trace is in progress)
+logging.pattern.level=%d{ABSOLUTE} [%X{traceId}/%X{spanId}] %-5p [%t] %C{2} - %m%n