如何使用 springboot 微服务获得用于跟踪的 req id？

Question

The ask is:

Whenever a client calls API's, i want to tag it with a unique identifier or use one supplied by the client (usually in a query param) and pass it across components until that request is fulfilled sucessfully or fails. The goal is to get a holistic picture of how a request was handled by different components and what happened at each component and quickly identify issues.

How can i achieve this using springboot microservices. please help me.

Answer 1

Spring Cloud Sleuth is what you are looking for: https://cloud.spring.io/spring-cloud-sleuth/reference/html/

Spring Cloud Sleuth's solution is to inject span and trace IDs into log entries. A trace ID is a unique identifier that an entire request flow will share. IA span is more local and is defined for each request received for each request sent event. They define particular interaction points.

The initial span, or root span, is generated when a client request is received from outside the distributed system. This request lacks trace and span information. The root span becomes the trace ID for the rest of the request flow through the system / systems.

The diagram below shows how Sleuth span and trace generation would work through a hypothetical service.network.

All you need to do in your code is to add the dependency spring-cloud-starter-sleuth and Spring will automatically instrument the following communication channels:

• requests over messaging technologies like Apache Kafka or RabbitMQ
• HTTP headers received at Spring MVC controllers
• requests made with the RestTemplate

Answer 2

If you want to start simple you could define a filter (eg by extending OncePerRequestFilter ) that generates/extracts a request ID. You can also put it into Logback's MDC so that it is included in every logging statement that is issued from the thread executing the request (if configured):

@Component
public class RequestIdFilter extends OncePerRequestFilter {

    private final ThreadLocal<String> requestId = new ThreadLocal<>();

    public Optional<String> getCurrentRequestId() {
        return Optional.ofNullable(requestId.get());
    }
    
    @Override
    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws ServletException, IOException {
        try {
            requestId.set(UUID.randomUUID().toString()); // or extract from request
            MDC.put("requestId", requestId.get());
            chain.doFilter(request, response);
        } finally {
            requestId.remove();
        }
    }
}