Handling exception from webservices called by OpenFeign - spring-boot

Question

I have several microservices and I use openfeign to call the different micro services.
the entry point for the global application is named dispatcher-ws. His role is to dispatch calls depending on the payload.
As entry I do have the following payload:
{
"operation": "signature",
"clientId": "abcdef",
...
"pdfDocument": "JVBERi0xLjMNCiXi48/TDQoNCjEg..."
}
I have microservice named signature-ws that handles pdf signature. So far, so good. I implemented my client this way:
#FeignClient(name="signature-ws", decode404 = true, url = "http://localhost:8080/signature-ws/api")
public interface SignatureClient {
#PostMapping("/signature")
Map<String, Object> signDocument(RequestDto request) throws AppServiceException;
}
In my service layer, I try to make the call depending on operation value:
#Service
public class RequestServiceImpl implements DispatchService {
private final RequestRepository requestRepository;
private final SignatureClient signatureClient;
private final Resilience4JCircuitBreakerFactory circuitBreakerFactory;
#Autowired
public DispatchServiceImpl(RequestRepository requestRepository,
SignatureClient signatureClient,
Resilience4JCircuitBreakerFactory circuitBreakerFactory) {
this.requestRepository = requestRepository;
this.signatureClient = signatureClient;
this.circuitBreakerFactory = circuitBreakerFactory;
}
#Override
public RequestDto handleRequest(RequestDto request) {
RequestDto returnValue = new RequestDto();
// if not initialized, throw null pointer exception...
returnValue.setPayloads(new ArrayList<>());
if(request.getOperation().equals("signature") {
Resilience4JCircuitBreaker circuitBreaker = circuitBreakerFactory.create("signature");
Supplier<Map<String, Object>> signatureResponseSupplier =
() -> signatureClient.signDocument(request);
Map<String, Object> signatureResponse = circuitBreaker.run(
signatureResponseSupplier,
throwable -> handleException()
);
...
returnValue.getResponses().add(signatureResponse)
}
return retunValue;
}
...
private Map<String, Object> handleException() {
Map<String, Object> returnValue = new HashMap<>();
returnValue.put("Error", "Error rmessage ... ");
returnValue.put("status", "Failure");
return returnValue;
}
If i don't pass pdfDocument in signature webservice, I do retrieve an exception.
{
"errorId": "Qe99DwntFrMPCAfuZfDQW1ucwNh5BK",
"status": "ERROR",
"operations": "signature",
"profile": "client123456",
"errorMessage": "PDF is missing",
"createdAt": 1647354022127
}
I would like to retrieve the exception response and pass the key values to the map in the handleException method. At this stage, it doesn't return anything and worse of all, i do return a 200 status.
I implemented a controllerAdvice that manage the response to return. This class is identical in all my web services(i should think about creating a micro service for handling all exceptions...)
#ControllerAdvice(basePackages = { "com.company.app" })
public class AppExceptionsHandler {
private final RequestContext requestContext;
#Autowired
public AppExceptionsHandler(RequestContext requestContext) {
this.requestContext = requestContext;
}
#ExceptionHandler(value = {AppServiceException.class})
public ResponseEntity<Object> handleAppException(AppServiceException ex,
WebRequest request) {
// récupérer le body
DispatchDto response = requestContext.getResponse();
ErrorMessage errorMessage = ErrorMessage.builder()
.errorId(response.getId())
.status(RequestOperationStatus.ERROR.name())
.operations(response.getOperations())
.profile(response.getProfile())
.errorMessage(ex.getMessage())
.createdAt(new Date())
.build();
}
return new ResponseEntity<>(errorMessage, new HttpHeaders(), HttpStatus.INTERNAL_SERVER_ERROR);
}
}
What i expect is to return the same exception in my dispatcher microservice.

Answer 1

I found a trick to solve this issue.
First I surrounded with a try catch my feign request :
try {
...
Map<String, Object> facturxResponse =
facturXClient.createFacturX(dispatchDto);
...
} catch(FeignException e) {
System.out.println(e.getMessage());
throw new AppServiceException(e.getMessage());
}
I noted that e.getMessage returns a string which has this pattern:
[500 Internal Server Error] during [POST] to [http://localhost:8080/my-ws/api/ws]
[FacturXClient#createFacturX(DispatchDto)]: [{"errorId":"z3o1bE8SJrm8WGrxlpIIWe6TNf0NzR","status":"ERROR","operations":"facturx","profile":"client123456","errorMessage":"PDF is missing","createdAt":1647422337344}]
I throw this exception and intercept the response
#ExceptionHandler(value = {AppServiceException.class})
public ResponseEntity<Object> handleUserServiceException(AppServiceException ex,
WebRequest request) throws JsonProcessingException {
String input = ex.getMessage();
String[] splitResponse = input.split(":", 4);
ObjectMapper mapper = new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT);
String response = splitResponse[3].trim().substring(1, splitResponse[3].trim().length() -1);
ErrorMessage errorMessage = mapper.readValue(response, ErrorMessage.class);
System.out.println(errorMessage.toString());
return new ResponseEntity<>(errorMessage, new HttpHeaders(), HttpStatus.INTERNAL_SERVER_ERROR);
}
I finally get the expected response:
{
"errorId": "z3o1bE8SJrm8WGrxlpIIWe6TNf0NzR",
"status": "ERROR",
"operations": "facturx",
"profile": "client123456",
"errorMessage": "PDF is missing",
"createdAt": "2022-03-16T09:18:57.344+00:00"
}