How to catch FeignClient exception

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.

Solution

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
    }

}