Spring Cloud Sleuth Zipkin example

When using a microservices architecture, a single transaction may span multiple microservices. If you want to debug any transaction or you want to investigate an issue, you need a unique id to identify the flow of transactions. Spring Cloud Sleuth provides the solution by implementing distributed tracing solution for Spring Cloud.

Spring Cloud Sleuth uses correlation IDs (traceid) to trace logs. A correlation ID is a unique number or string (e.g. order id, user id) that's assigned to a transaction when a transaction is initiated. As the transaction flows across multiple services, the correlation ID is propagated from one service call to another. With Spring Cloud Sleuth, you'll automatically get correlation IDs added to the log statements you put in your microservices.

We will also configure Zipkin in these microservices so that API call statistics will be send to Zipkin server. Zipkin is a distributed tracing platform that will allow us to trace transactions across multiple service invocations. Using Zipkin we can graphically check the time consumed by each microservice API.

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>   
    <version>2.1.6.RELEASE</version>
    <relativePath />
</parent>

<properties>
    <java.version>1.8</java.version>
    <spring-cloud.version>2.1.3.RELEASE</spring-cloud.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-sleuth</artifactId>
        <version>${spring-cloud.version}</version>
    </dependency>

<dependency>
	<groupId>org.springframework.cloud</groupId>
	<artifactId>spring-cloud-sleuth-zipkin</artifactId>
	<version>${spring-cloud.version}</version>
</dependency>
        
</dependencies>

Add SleuthApplication, SleuthRestController classes and application.yml file. SleuthRestController will expose an endpoint that will we will call from browser and it will internally call second microservice to get the results. By default Zipkin server runs at port 9411. It it is running on some other port or host, we can configure the zipkin url using spring.zipkin.baseUrl property in application.yml file.

We will need to define how often each service should write data to Zipkin. By default only 10% data is sent to Zipkin. However for our testing purpose we can make it 100% by using spring.sleuth.sampler.percentage property which should be set between 0 & 1. It is not recommended to set it to 1 as it will put hugh load on Zipkin server.

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
public class SleuthApplication {

    public static void main(String[] args) {
        SpringApplication.run(SleuthApplication.class, args);
    }
    
    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }

}       

package com.example;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class SleuthRestController {

    private final Logger LOG = LoggerFactory.getLogger(this.getClass());

    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping(value = "/api")
    public String hello() {
        LOG.info("Hello Sleuth");

        return restTemplate.getForObject("http://localhost:8082/api2", String.class);
    }

}   

spring:
  application:
    name: sleuth-demo
  zipkin:
    baseUrl: http://localhost:9411
  sleuth:
    sampler:
      probability: 1.0
     
server:
  port: 8081  

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SleuthApplication2 {

    public static void main(String[] args) {
        SpringApplication.run(SleuthApplication2.class, args);
    }

}       

package com.example;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class SleuthRestController {
    
    private final Logger LOG = LoggerFactory.getLogger(this.getClass());

    
    @RequestMapping(value = "/api2") 
    public String hello() {
        LOG.info("Hello Sleuth you have invoked second microservice");
        return "Hello Sleuth you have invoked second microservice";
    }

}  

spring:
  application:
    name: sleuth-demo-2
  zipkin:
    baseUrl: http://localhost:9411
  sleuth:
    sampler:
      probability: 1.0
     
server:
  port: 8082 

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
    <spring-cloud.version>Edgware.RELEASE</spring-cloud.version>
</properties>

<dependencies>
    <dependency>
        <groupId>io.zipkin.java</groupId>
        <artifactId>zipkin-server</artifactId>
    </dependency>
    <dependency>
        <groupId>io.zipkin.java</groupId>
        <artifactId>zipkin-autoconfigure-ui</artifactId>
    </dependency>
    <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
    </dependency>
</dependencies>     

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

import zipkin.server.EnableZipkinServer;


@EnableZipkinServer
@SpringBootApplication
public class ZipkinServiceApplication {

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

Console Output :

Observe the logs in SleuthApplication, it prints sleuth-demo,61a0a37a9c5988af,61a0a37a9c5988af,true

Observe the logs in SleuthApplication2, it prints sleuth-demo-2,61a0a37a9c5988af,f7d587d622ac96cc,true where f7d587d622ac96cc is the span id.