spring feign client exception handling

Question

I have some fiegn client to send request other micro service.

@FeignClient(name="userservice")
public interface UserClient {

    @RequestMapping(
        method= RequestMethod.GET,
        path = "/userlist"
    )
    String getUserByid(@RequestParam(value ="id") String id);
}

Now I am sending request like this

try {
    String responseData = userClient.getUserByid(id);
    return responseData;
} catch(FeignException e) {
    logger.error("Failed to get user", id);
} catch (Exception e) {
    logger.error("Failed to get user", id);
}

Here the problem is if any FeignException happens I don't get any error code.

I need to send a corresponding error codes in other APIS to send to caller

So how to extract the error code? I want to extract error code and build a responseEntity

I got this code but dont know how exactly I can use in my function.

Answer 1

I'm late to party but here are my 2 cents. We had same use case to handle exceptions based on error code and we used custom ErrorDecoder.

public class CustomErrorDecoder implements ErrorDecoder {

    @Override
    public Exception decode(String methodKey, Response response) {
        String requestUrl = response.request().url();
        Response.Body responseBody = response.body();
        HttpStatus responseStatus = HttpStatus.valueOf(response.status());

        if (responseStatus.is5xxServerError()) {
            return new RestApiServerException(requestUrl, responseBody);
        } else if (responseStatus.is4xxClientError()) {
            return new RestApiClientException(requestUrl, responseBody);
        } else {
            return new Exception("Generic exception");
        }
    }
}

Return @Bean of above class in FeignClientConfiguration class.

public class MyFeignClientConfiguration {

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

Use this as your config class for FeignClient.

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

Then you can handle these exceptions using GlobalExceptionHandler.

Answer 2

Not the same issue, but this helped in my situation. OpenFeign's FeignException doesn't bind to a specific HTTP status (i.e. doesn't use Spring's @ResponseStatus annotation), which makes Spring default to 500 whenever faced with a FeignException. That's okay because a FeignException can have numerous causes that can't be related to a particular HTTP status.

However you can change the way that Spring handles FeignExceptions. Simply define an ExceptionHandler that handles the FeignException

@RestControllerAdvice
public class GlobalExceptionHandler {

    @ExceptionHandler(FeignException.class)
    public String handleFeignStatusException(FeignException e, HttpServletResponse response) {
        response.setStatus(e.status());
        return "feignError";
    }

}

This example makes Spring return the same HTTP status that you received

Answer 3

did you try to implement FallbackFactory on your feign client ?

https://cloud.spring.io/spring-cloud-netflix/multi/multi_spring-cloud-feign.html#spring-cloud-feign-hystrix-fallback

On the create method, before return, you can retrieve the http status code with this snippet :

String httpStatus = cause instanceof FeignException ? Integer.toString(((FeignException) cause).status()) : "";

Exemple :

    @FeignClient(name="userservice", fallbackFactory = UserClientFallbackFactory.class)
    public interface UserClient {
    
        @RequestMapping(
                method= RequestMethod.GET,
                          path = "/userlist")
        String getUserByid(@RequestParam(value ="id") String id);
    
    }
    
    
    @Component
    static class UserClientFallbackFactory implements FallbackFactory<UserClient> {
        @Override
        public UserClient create(Throwable cause) {
    
         String httpStatus = cause instanceof FeignException ? Integer.toString(((FeignException) cause).status()) : "";
    
         return new UserClient() {
            @Override
            public String getUserByid() {
                logger.error(httpStatus);
                // what you want to answer back (logger, exception catch by a ControllerAdvice, etc)
            }
        };
    }
   }

Answer 4

I'm kinda late too, but I wanted to make sure you check out other potential solutions as well.

Feign with Spring has a notoriously bad way of handling exceptions so I came up with a custom solution that creates this robust environment to define your business exceptions the way you want.

It's utilizing a custom ErrorDecoder registered to the Feign clients and adds the possibility to customize your exception handling based on method or class level.

Check it out: Maintainable error handling with Feign clients? Not a dream anymore

Answer 5

There's a ErrorDecored interface for that like it says in the documentation

The answer above about FallbackFactory is viable but falls into some other layer of abstraction.

Answer 6

String errorJson = e.contentUTF8();

HttpStatus status = HttpStatus.valueOf(e.status());

Map<String, List> errorResponse = objectMapper.readValue(errorJson, Map.class);

new ResponseDTO(status,e.status(), errorResponse.get("errors").get(0));