How to correlate log events in distributed Vertx system

Question

while doing logs in the multiple module of vertx, it is a basic requirement that we should be able to correlate all the logs for a single request.

as vertx being asy

Answer 1

There's a surprising lack of good answers published about this, which is odd, given how easy it is.

Assuming you set the correlationId in your MDC context on receipt of a request or message, the simplest way I've found to propagate it is to use interceptors to pass the value between contexts:

vertx.eventBus()
        .addInboundInterceptor(deliveryContext -> {
            MultiMap headers = deliveryContext.message().headers();
            if (headers.contains("correlationId")) {
                MDC.put("correlationId", headers.get("correlationId"));
                deliveryContext.next();
            }
        })
        .addOutboundInterceptor(deliveryContext -> {
            deliveryContext.message().headers().add("correlationId", MDC.get("correlationId"));
            deliveryContext.next();
        });