Spring Boot not logs Mapped Diagnostic Context (MDC) on exception

Question

I need to have Mapped Diagnostic Context data in logs. Application build with:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.8.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
</parent>

To get MDC in logs I put in application.properties file:

logging.pattern.level=%X{mdcData}%5p

and create a class

@Component
public class RequestFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        try {
            // Setup MDC data:
            String mdcData = String.format("[userId:%s | requestId:%s] ", "hello", "hello");
            MDC.put("mdcData", mdcData); //Variable 'mdcData' is referenced in Spring Boot's logging.pattern.level property
            chain.doFilter(request, response);
        } finally {
           // Tear down MDC data:
           // ( Important! Cleans up the ThreadLocal data again )
            MDC.clear();
        }
    }
...
}

The MDC data appears in logs when I use method call like log.info("message here") . I tried with levels INFO, WARN, ERROR - it is fine. But when I get RuntimeException in my controller, I see the stack trace in logs with ERROR level, but no MDC data provided.

What should I do to get MDC data in logs on exception thrown?

Answer 1

You may write a block catching Exception before MDC.clear() in order to log in doFilter like below.

        try {
            // Setup MDC data:
            String mdcData = String.format("[userId:%s | requestId:%s] ", "hello", "hello");
            MDC.put("mdcData", mdcData); //Variable 'mdcData' is referenced in Spring Boot's logging.pattern.level property
            chain.doFilter(request, response);
        } catch (Exception e) {
            log.error("", e);
        } finally {
           // Tear down MDC data:
           // ( Important! Cleans up the ThreadLocal data again )
            MDC.clear();
        }

It changes logger from DirectJDKLog to RequestFilter.