SpringBoot Microservices tracing with Zipkin and Sleuth

In this article, we are going to understand the microservices distributed tracing using Zipkin and Spring cloud sleuth framework.

Microservices are great architecture, though its comes with its own challenges. Complex microservices architecture have downstream and upstream dependencies with other microservices and everything is interconnected. Most of the time individual team just focus on their own services, so in microservices distributed environment it’s very difficult to find any latency or trace the actual issues at runtime.

1. Distributed Tracing

As the complexity of microservices architecture increases, uniform observability across the services and server instances become critical. Each service requests passes through multiple services layer, identifying latency or any run-time issues becomes increasingly difficult using traditional debugging techniques. Distributed tracing provides a holistic view of requests transiting through multiple services, allowing for immediate identification of issues.

1.1 Distributed Tracing Vocabulary

• Span – A span is an individual operation.
• Trace – A Trace is an end-to-end latency graph, composed of spans.
• Tracers – Tracers records spans and passes context required to connect them into a trace.

2. Zipkin

Zipkin is an open source distributed system that provides mechanisms for sending, receiving, storing, and visualizing traces details. This helps team to correlate activities between server instances and get a much deeper understanding of exactly what is going on in our services. Zipkin provide the UI interface to analyze the traces and call graph details between services.

2.1 Zipkin Installation

There are three different ways zipkin server can be installed.

• Java – We can execute the below wget command to download the latest zipkin server. In case we don’t have wget installed, simply we can copy the below url and paste into our browser to download the latest zipkin server.

wget -O zipkin.jar 'https://search.maven.org/remote_content?g=io.zipkin.java&a=zipkin-server&v=LATEST&c=exec'

• Zipkin source – We can download the zipkin source code from below github url and run the zipkin application in your local machine: https://github.com/openzipkin/zipkin
• Docker – We can download the docker-zipkin container from https://github.com/openzipkin/docker-zipkin

For this sample application I have installed the Zipkin server using the Java method.

2.2 Zipkin UI

Zipkin UI provides following features to analyze the distributed tracing details across services:

• Search traces by service name, span name etc
• Trace dependency graph showing trace requests flow across services
• Provides the details of total trace time for each individual span

By analyzing the details provided by Zipkin UI, it becomes easier to find the latency or any particular services issues across the interconnected microservices architecture.

3. Spring Cloud Sleuth

Spring cloud sleuth add traces and span ids to the Slf4j MDC (Mapped Diagnostic context), to extract logs from a given trace or span. Sleuth provide abstraction over common distributed tracing data models like traces, spans, annotations, key-value annotations. Sleuth instruments common ingress and egress points from Spring applications (servlet filter, rest template, scheduled actions, message channels, zuul filters, feign client).

3.1 Sleuth and Zipkin configuration at SpringBoot

Add following dependencies to the Springboot pom.xml to add the zipkin and spring cloud sleuth into the SpringBoot application.

pom.xml

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-sleuth</artifactId>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-zipkin</artifactId>
</dependency>

4. Sample Application

For this article I have created a sample application which consist of three different microservices called UserGreetingService, UserNameService, UserAddressService.

UserGreetingService interns makes a call to UserNameService and UserAddressService services to constructs the complete greeting message for a user along with name and address details.

UserGreetingService.java

@SpringBootApplication
@RestController
@CrossOrigin
public class UserGreetingService {
	
	@RequestMapping("/api/user/greet")
	public String greet() {
		String greetingMsg = "Hello";
		String userName = restTemplate().getForObject("http://localhost:3001/api/user/name", String.class);
		String userAddress = restTemplate().getForObject("http://localhost:3002/api/user/address", String.class);
		
		return greetingMsg + " " + userName + "!\n\n" + userAddress;
	}
	
	@Bean
	RestTemplate restTemplate() {
		return new RestTemplate();
	}
	
	public static void main(String[] args) {
		SpringApplication.run(UserGreetingService.class,
				"--spring.application.name=user-greeting-service",
				"--server.port=3000"
		);
	}
}

To introduce the services latency, I have added Thread.sleep(1000) and Thread.sleep(2000) intentionally to UserNameService and UserAddressService services.

You can download the sample code from the github link – Sign up