How to catch FeignClient exception - spring-mvc

Question

I try to catch exception wich I received from another microservice connected by FeignClient. I've made custom ErrorDecoder, and
public class CustomErrorDecoder implements ErrorDecoder {
private final Logger log = LoggerFactory.getLogger(getClass());
private final ErrorDecoder defaultErrorDecoder = new Default();
#Override
public Exception decode(String methodKey, Response response) {
if (response.status() >= 400 && response.status() <= 499) {
log.info("----------------- "+methodKey+" , "+response.status()+" , "+ response.reason());
return new RestApiException(99,99,"");
}
return defaultErrorDecoder.decode(methodKey, response);
}
}
Where RestApiException extends Exception.
#ControllerAdvice
public class GlobalControllerAdvice {
private final Logger log = LoggerFactory.getLogger(getClass());
#ExceptionHandler(RestApiException.class)
public ResponseEntity<RestApiException> handleException(RestApiException exception, HttpServletRequest req) {
log.error("Sending error to client ( "+req.getUserPrincipal().getName()+" ) \"{}\"", exception.getErrMsg());
return new ResponseEntity<RestApiException>(exception, exception.getStatus());
}
#ExceptionHandler(Throwable.class)
public ResponseEntity<RestApiException> handleException(Throwable throwable, HttpServletRequest req) {
RestApiException exception=new RestApiException(HttpStatus.INTERNAL_SERVER_ERROR, 100, 100,
throwable.getMessage());
return handleException(exception, req);
}
As a result, when I get <--- HTTP/1.1 400 Bad Request (5380ms)
I've got default error messages
HttpStatus.INTERNAL_SERVER_ERROR, 100, 100,
throwable.getMessage());
but not expexted custom exception, which I try to set in CustomErrorDecoder.
What I'm doing wrong, why I can't call RetAppiException and return error answer to rest client.
Thanks.

Answer 1

You can't catch the exception of the FeignClient with a #ControllerAdvice. The exception handler will not catch the exceptions generated by the feign client, error decoder..
A simple solution would be catch your feign calls, and then throw the exception you want.
try{
feignClient.method();
} catch(Exception ex){
//throw exceptions you want
throw new YourException();
}
Then you'll be able to handle it:
#ControllerAdvice
public class GlobalControllerAdvice {
private final Logger log = LoggerFactory.getLogger(getClass());
#ExceptionHandler(YourException.class)
public ResponseEntity<RestApiException> handleException(RestApiException exception, HttpServletRequest req) {
//impl
}
}

Answer 2

You can catch feign client exceptions by catching HystrixRuntimeException and casting the getCause() to FeignClientException.
Example:
#ExceptionHandler
public ResponseEntity<Problem> handleFeignException(HystrixRuntimeException ex, NativeWebRequest request) {
final FeignException.FeignClientException feignClientException = (FeignException.FeignClientException) ex.getCause();
return handleException(feignClientException, request);
}