how to log Spring 5 WebClient call

Question

I\'m trying to log a request using Spring 5 WebClient. Do you have any idea how could I achieve that?

(I\'m using Spring 5 and Spring boot 2)

The code looks

Answer 1

@StasKolodyuk's answer elaborates on the solution from baeldung for logging the response body of a reactive WebClient. Note that

tc.bootstrap(...)

is deprecated in

    HttpClient httpClient = HttpClient
      .create()
      .tcpConfiguration(
        tc -> tc.bootstrap(
          b -> BootstrapHandlers.updateLogSupport(b, new CustomLogger(HttpClient.class))))
      .build()

Another non-deprecated way to add your custom LoggingHandler is (Kotlin)

val httpClient: HttpClient = HttpClient.create().mapConnect { conn, b ->
    BootstrapHandlers.updateLogSupport(b, CustomLogger(HttpClient::class.java))
    conn
}

Answer 2

You can easily do it using ExchangeFilterFunction

Just add the custom logRequest filter when you create your WebClient using WebClient.Builder.

Here is the example of such filter and how to add it to the WebClient.

@Slf4j
@Component
public class MyClient {

    private final WebClient webClient;

    // Create WebClient instance using builder.
    // If you use spring-boot 2.0, the builder will be autoconfigured for you
    // with the "prototype" scope, meaning each injection point will receive
    // a newly cloned instance of the builder.
    public MyClient(WebClient.Builder webClientBuilder) {
        webClient = webClientBuilder // you can also just use WebClient.builder()
                .baseUrl("https://httpbin.org")
                .filter(logRequest()) // here is the magic
                .build();
    }

    // Just example of sending request
    public void send(String path) {
        ClientResponse clientResponse = webClient
                .get().uri(uriBuilder -> uriBuilder.path(path)
                        .queryParam("param", "value")
                        .build())
                .exchange()
                .block();
        log.info("Response: {}", clientResponse.toEntity(String.class).block());
    }

    // This method returns filter function which will log request data
    private static ExchangeFilterFunction logRequest() {
        return ExchangeFilterFunction.ofRequestProcessor(clientRequest -> {
            log.info("Request: {} {}", clientRequest.method(), clientRequest.url());
            clientRequest.headers().forEach((name, values) -> values.forEach(value -> log.info("{}={}", name, value)));
            return Mono.just(clientRequest);
        });
    }

}

Then just call myClient.send("get"); and log messages should be there.

Output example:

Request: GET https://httpbin.org/get?param=value
header1=value1
header2=value2