Distributed tracing with Sleuth

Another one of Spring Cloud's essential functionalities is distributed tracing. It is implemented in the Spring Cloud Sleuth library. Its primary purpose is to associate subsequent requests dispatched between different microservices under processing single input request. As in most cases, these are HTTP requests that implement tracing mechanisms based on HTTP headers. The implementation is built over Slf4j and MDC. Slf4j provides facade and abstraction for specific logging frameworks such as logback, log4j, or java.util.logging. MDC or mapped diagnostic context in full, is a solution for distinguishing log output from different sources and enriching them with additional information that could be not available in the actual scope.

Spring Cloud Sleuth adds trace and span IDs to the Slf4J MDC, so that we are able to extract all of the logs with a given trace or span. It also adds some other entries such as application name or exportable flag. It integrates with...