spring webclient: retry with backoff on specific error

Question

i\'d like to retry the request 3 times after waiting 10sec when response is 5xx. but i don\'t see a method that I can use. On object

WebClient.builder()
             


        

Answer 1

You can do this taking the following approach:

• Use the exchange() method to obtain the response without an exception, and then throw a specific (custom) exception on a 5xx response (this differs from retrieve() which will always throw WebClientResponseException with either a 4xx or 5xx status);
• Intercept this specific exception in your retry logic;
• Use reactor-extra - it contains a nice way to use retryWhen() for more complex & specific retries. You can then specify a random backoff retry that starts after 10 seconds, goes up to an arbitrary time and tries a maximum of 3 times. (Or you can use the other available methods to pick a different strategy of course.)

For example:

//...webclient
.exchange()
.flatMap(clientResponse -> {
    if (clientResponse.statusCode().is5xxServerError()) {
        return Mono.error(new ServerErrorException());
    } else {
        //Any further processing
    }
}).retryWhen(
    Retry.anyOf(ServerErrorException.class)
       .randomBackoff(Duration.ofSeconds(10), Duration.ofHours(1))
       .maxRetries(3)
    )
);