error handling with reactiveFeignClient and CircuitBreaker - spring-boot

Question

we are using reactive feign client (com.playtika.reactivefeign:feign-reactor-spring-cloud-starter:3.2.0)
circuit breaker version : org.springframework.cloud:spring-cloud-starter-circuitbreaker-reactor-resilience4j:2.1.0
and spring boot application version org.springframework.boot’ version ’2.6.6
when we get an error from reactive feign client (such as 404 error)
#ReactiveFeignClient(name = "someRestClient", url = "${react-gpi-service.url}",configuration = AuthConfigurationsomeRestClient.class, fallbackFactory = someRestClienttFallbackFactory.class)
#Profile("!test")
public interface someRestClient {
#PostMapping(value = "/v2/{entity}/any", produces = MediaType.ALL_VALUE, consumes = MediaType.APPLICATION_JSON_VALUE)
Mono<String> any(#PathVariable(value = "entity")
it goes over the error decoder to check if it should be retried
#Slf4j
#RequiredArgsConstructor
public class RetryableErrorDecoder implements ErrorDecoder {
private static ErrorDecoder defaultErrorDecoder = new Default();
private final String clientName;
public Exception decode(String methodKey, Response response) {
String body = "";
try {
body = IOUtils.toString(response.body().asInputStream(), StandardCharsets.UTF_8);
} catch (Exception e) {
log.error("failed to parse error response body", e);
}
log.error("In RetryableErrorDecoder, got an error from {}. status: {}, body: {}, reason: {}, request: {}",
clientName, response.status(), body, response.reason(), response.request());
if (response.status() == HttpStatusCodes.STATUS_CODE_SERVICE_UNAVAILABLE ||
response.status() == HttpStatusCodes.STATUS_CODE_BAD_GATEWAY) {
log.warn("Retry on error 503 or 502");
return createRetryableException(response, "Service Unavailable 503, 502");
} else {
Exception decode = defaultErrorDecoder.decode(methodKey, response);
if (decode instanceof FeignException &&
decode.getMessage().contains("authorizing")) {
log.warn("Retry on {}", decode.getMessage());
return createRetryableException(response, "Service authorizing problem");
}
return decode;
}
}
private Exception createRetryableException(Response response, String message) {
return new RetryableException(
response.status(),
message,
response.request().httpMethod(),
null,
null,
response.request());
}
}
after that it goes to Circuit beaker predicate
public class someFailurePredicate implements Predicate<Throwable> {
#Override
public boolean test(Throwable throwable) {
return throwable instanceof ThirdPartyException
|| throwable instanceof ReadTimeoutException
|| throwable instanceof OutOfRetriesException;
}
}
and then it goes to fallBackFactory mechanism because the circuit breaker requires the fallback method so the circuit breaker predicate is activated again.
#Component
public class someRestClientFallbackFactory implements FallbackFactory<someRestClient> {
#Override
public someRestClient apply(Throwable throwable) {
return new someRestClientFallback(throwable);
}
}
public class someRestClientFallback implements someRestClient {
private final Throwable cause;
public someClientFallback(Throwable cause) {
this.cause = cause;
}
public Mono<String> performSearchRequest(String entity,
) {
return Mono.error(cause);
}
}
because we have 2 mechanisms of error handling the circuit predicate is calling twice and duplicating the error.
I tried to move the retry mechanism(error decoder) to fallback method but the fallbackfactory method accepts throwable and reactiveFeignClientException doesn't have a status code and it's hard to determine if we should do the retry.
if I remove the fallback method I get this error message :
org.springframework.cloud.client.circuitbreaker.NoFallbackAvailableException: No fallback available.
we need to add it but then we have two mechanisms and a duplicate circuit breaker predicate count

Answer 1

Reactive Feign Client enables its own CB by default, it is possible to disable it by setting reactive.feign.circuit.breaker.enabled to false - https://github.com/PlaytikaOSS/feign-reactive/blob/develop/feign-reactor-spring-configuration/README.md