Handling feign exception in Spring boot using RestControllerAdvice

Question

I have some Fiegn client to send request other springboot micro service.

 @ExceptionHandler(FeignException.class)
    public ResponseEntity<ApiError> handleFeignException(FeignException ex, WebRequest webRequest) throws JsonProcessingException {
           try{
            ObjectMapper objectMapper = JsonMapper.builder()
                    .findAndAddModules()
                    .build();
            ApiError apiError = objectMapper.readValue(ex.contentUTF8(), ApiError.class);
               return new ResponseEntity<>(apiError, HttpStatusCode.valueOf(ex.status()));
    
        } catch (JsonProcessingException e) {
            log.error("Error deserializing Feign exception: {}", e.getMessage());
            ApiError fallbackError = new ApiError("Error deserializing Feign exception", LocalDate.now(), ex.status(), webRequest.getDescription(false));
            return ResponseEntity.status(HttpStatusCode.valueOf(ex.status()))
                    .body(fallbackError);
        }
    }

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
@ToString
public class ApiError {
    private String message;
    private LocalDate timeStamp;
    private int status;
    private String requestPath;
}

So I am handling feign exception thrown by feign client during inter service communication between spring boot micro services this way.... Is there any other good approach or am i doing it the correct way

Answer 1

What you have is another way to handle exception, but what I could suggest you is to have custom ErrorDecoder according to Custom-error-handling on the wiki page of OpenFeign.

As an example:

public class CustomErrorDecoder implements ErrorDecoder {

    @Override
    public Exception decode(String methodKey, Response response) {
        if (response.status() >= 400 && response.status() <= 499) {
            return new StashClientException(
                    response.status(),
                    response.reason()
            );
        }
        if (response.status() >= 500 && response.status() <= 599) {
            return new StashServerException(
                    response.status(),
                    response.reason()
            );
        }
        return errorStatus(methodKey, response);
    }
}

After declaring it create a configuration class, Beside of ErrorDecoder you could also declare: custom filters, interceptors in this class.

@Configuration
public class MyFeignClientConfiguration {

    @Bean
    public ErrorDecoder errorDecoder() {
        return new CustomErrorDecoder();
    }
}

And in the Feign Interface you will have:

@FeignClient(
    value = "myFeignClient", 
    configuration = MyFeignClientConfiguration.class
)