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Spring Cloud Sleuth

2.2.4

Spring Cloud Sleuth provides Spring Boot auto-configuration for distributed tracing.

Features

Sleuth configures everything you need to get started. This includes where trace data (spans) are reported to, how many traces to keep (sampling), if remote fields (baggage) are sent, and which libraries are traced.

Specifically, Spring Cloud Sleuth…​

  • Adds trace and span ids to the Slf4J MDC, so you can extract all the logs from a given trace or span in a log aggregator.

  • Instruments common ingress and egress points from Spring applications (servlet filter, rest template, scheduled actions, message channels, feign client).

  • If spring-cloud-sleuth-zipkin is available then the app will generate and report Zipkin-compatible traces via HTTP. By default it sends them to a Zipkin collector service on localhost (port 9411). Configure the location of the service using spring.zipkin.baseUrl.

Spring Boot Config

Add Sleuth to your classpath:

Maven

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-dependencies</artifactId>
            <version>${release.train.version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>
<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-sleuth</artifactId>
    </dependency>
</dependencies>

Gradle

buildscript {
    dependencies {
        classpath "io.spring.gradle:dependency-management-plugin:0.5.2.RELEASE"
    }
}

apply plugin: "io.spring.dependency-management"

dependencyManagement {
     imports {
          mavenBom "org.springframework.cloud:spring-cloud-dependencies:${releaseTrainVersion}"
     }
}
dependencies {
    compile 'org.springframework.cloud:spring-cloud-starter-sleuth'
}

As long as Spring Cloud Sleuth is on the classpath any Spring Boot application will generate trace data:

@SpringBootApplication
@RestController
public class Application {

  private static Logger log = LoggerFactory.getLogger(DemoController.class);

  @RequestMapping("/")
  public String home() {
    log.info("Handling home");
    return "Hello World";
  }

  public static void main(String[] args) {
    SpringApplication.run(Application.class, args);
  }

}

Run this app and then hit the home page. You will see traceId and spanId populated in the logs. If this app calls out to another one (e.g. with RestTemplate) it will send the trace data in headers and if the receiver is another Sleuth app you will see the trace continue there.

  • Instead of logging the request in the handler explicitly, you could set logging.level.org.springframework.web.servlet.DispatcherServlet=DEBUG

  • Sleuth defaults to a rate limited sampler. That means that it will sample up to 1000 transactions per second.

  • Set spring.application.name=bar (for instance) to see the service name as well as the trace and span ids.

Spring Initializr

Quickstart Your Project

Bootstrap your application with Spring Initializr.

Documentation

Each Spring project has its own; it explains in great details how you can use project features and what you can achieve with them.
2.2.4 SNAPSHOT CURRENT Reference Doc. API Doc.
3.0.0 M2 PRE Reference Doc. API Doc.
2.2.3 CURRENT GA Reference Doc. API Doc.
2.1.7 SNAPSHOT Reference Doc. API Doc.
2.1.6 GA Reference Doc. API Doc.