Java distributed tracing implementation compatible with Zipkin backend
...This repository includes dependency-free Java libraries and instrumentation for common components used in production services. For example, this includes trace filters for Servlet and log correlation for Apache Log4J. Brave's dependency-free tracer library works against JRE6+. This is the underlying api that instrumentation use to time operations and add tags that describe them. This library also includes code that parses X-B3-TraceId headers.
...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. Add Spring Cloud Sleuth to the classpath of a Spring Boot application (together with a Tracer implementation) and you will see trace IDs in logs.