Propagating correlation-id not working - spring

Question

I have the problem that the correlation-id is not propagated from my first to the my second microservice. I started to implement a servlet filter, a context and a context-holder as follows:
#Component
// Do not name bean "RequestContextFilter", otherwise filter will not work!
public class CallContextFilter implements Filter {
#Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
throws IOException, ServletException {
HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;CallContextHolder.getContext().setCorrelationId(httpServletRequest.getHeader(CallContext.CORRELATION_ID));
filterChain.doFilter(httpServletRequest, servletResponse);
}
#Override
public void init(FilterConfig filterConfig) throws ServletException {
}
#Override
public void destroy() {
}
}
#Component
#Getter
#Setter
public class CallContext {
public static final String CORRELATION_ID = "correlation-id";
private String correlationId = new String();
}
public class CallContextHolder {
private static final ThreadLocal<CallContext> userContext = new ThreadLocal<>();
public static final CallContext getContext() {
CallContext context = userContext.get();
if (context == null) {
context = new CallContext();
userContext.set(context);
}
return userContext.get();
}
}
Then, I implemented a RestTemplate bean as follows:
#Bean
public RestTemplate getRestTemplate() {
RestTemplate template = new RestTemplate();
List<ClientHttpRequestInterceptor> interceptors = template.getInterceptors();
interceptors.add(new CallContextInterceptor());
return template;
}
and the interceptor looks as follows:
public class CallContextInterceptor implements ClientHttpRequestInterceptor {
#Override
public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
HttpHeaders headers = request.getHeaders();
headers.add(CallContext.CORRELATION_ID, CallContextHolder.getContext().getCorrelationId());
return execution.execute(request, body);
}
}
When I call my endpoint, the servlet filter is executed and the correlation-id is stored in the CallContextHolder. So far, so good. However, the CallContextInterceptor seems to be called in an other thread and my ThreadLocal variable in the CallContextHolder is null. What I have to do to make this working?
#GetMapping("/ping")
public String ping() {
return pongRestTemplateClient.getPong();
}

Answer 1

Why not use Spring Cloud Sleuth and just let the libary do the work for you? http://cloud.spring.io/spring-cloud-sleuth/spring-cloud-sleuth.html

Answer 2

The problem was that I'm using Hysterix. Hystrix spawns a new thread to execute the code, completely unaware of the "outer" thread context. So, the executing thread losses access to the ThreadLocal dependant functionality when using Hysterix commands.
I found an answer to my problem here: https://github.com/jmnarloch/hystrix-context-spring-boot-starter