Spring Webflux, log response body from reactive http request only in debug mode

Question

Small question regarding how to log response body from HTTP request sent from a Webflux Webclient, but only in debug mode please.

Currently, in the app, I am making reactive http outbound calls this way:

webClient.mutate()
         .baseUrl(someURL)
         .build()
         .post()
         .uri(someRoute)
         .body(BodyInserters.fromValue(myRequest))
         .retrieve()
         .bodyToMono(String.class);

This is working fine. However, sometimes, there are issues, and I would like to see the response body for debugging.

Therefore, I took the wrong decision to use.log()

webClient.mutate()
         .baseUrl(someURL)
         .build()
         .post()
         .uri(someRoute)
         .body(BodyInserters.fromValue(myRequest))
         .retrieve()
         .bodyToMono(String.class)
         .log();

And this is great, I was able to see some logs, it resemble to something like this:

[ctor-http-nio-3] reactor.Mono.LiftFuseable.1              : | onSubscribe([Fuseable] ScopePassingSpanSubscriber)
[ctor-http-nio-3] reactor.Mono.LiftFuseable.1              : | request(unbounded)
[ctor-http-nio-3] reactor.Mono.LiftFuseable.1              : | onNext({foo='bar'})
[ctor-http-nio-3] reactor.Mono.LiftFuseable.1              : | onComplete()

However, I am now logging this no matter the log level...

No matter the level I set using logging.level.root=DEBUG I am always seeing the logs now.

May I ask how to achieve this, but for debug log level only please? I am looking at the API, and it seems.log() can take parameter, but I am not able to make it work only for debug.

Or maybe some other ways to achieve logging response body only at debug level would be great.

Thank you

Answer 1

You can conditionally tack on the log() based on logging level (or some other profile/environment indicator).

Mono<String> makeCall(final WebClient webClient, final ?? myRequest) { 
   final Mono<String> response = webClient.mutate()
                                          .baseUrl(someURL)
                                          .build()
                                          .post()
                                          .uri(someRoute)
                                          .body(BodyInserters.fromValue(myRequest))
                                          .retrieve()
                                          .bodyToMono(String.class);

    if (LOG.isDebugEnabled()) {
        return response.log();
    }
    return response;
}