Spring Cloud Gateway Global Exception handling and custom error response - spring-cloud

Question

I have a custom filter that authenticates every request before calling the actual API using Spring Cloud Gateway. Is there any way in Spring Cloud to handle exceptions centrally same as the Spring provide #ControllerAdvice? I want to handle exceptions globally and return custom error responses from the gateway.

Answer 1

Once an exception is thrown from your authentication filter, you can customize the error response by overriding the DefaultErrorAttributes class.
#Component
public class GlobalErrorAttributes extends DefaultErrorAttributes {
private static final Logger logger = LoggerFactory.getLogger(GlobalErrorAttributes.class);
public GlobalErrorAttributes() {
}
public GlobalErrorAttributes(boolean includeException) {
super(includeException);
}
#Override
public Map<String, Object> getErrorAttributes(ServerRequest request,
boolean includeStackTrace) {
Throwable error = this.getError(request);
logger.error("Error occured", error);
MergedAnnotation<ResponseStatus> responseStatusAnnotation = MergedAnnotations
.from(error.getClass(), MergedAnnotations.SearchStrategy.TYPE_HIERARCHY).get(ResponseStatus.class);
HttpStatus errorStatus = findHttpStatus(error, responseStatusAnnotation);
logger.info("errorStatus: {}", errorStatus);
Map<String, Object> map = super.getErrorAttributes(request, includeStackTrace);
String errorCode = getErrorCode(map, errorStatus);
map.remove("timestamp");
map.remove("path");
map.remove("error");
map.remove("requestId");
map.put("errorCode", errorCode);
return map;
}
private HttpStatus findHttpStatus(Throwable error, MergedAnnotation<ResponseStatus> responseStatusAnnotation) {
if (error instanceof ResponseStatusException) {
return ((ResponseStatusException) error).getStatus();
}
return responseStatusAnnotation.getValue("code", HttpStatus.class).orElse(INTERNAL_SERVER_ERROR);
}
private String getErrorCode(Map<String, Object> map, HttpStatus errorStatus) {
String errorCode;
switch (errorStatus) {
case UNAUTHORIZED:
errorCode = "401 UnAuthorized";
break;
case NOT_FOUND:
logger.error("The url:{} is not found", map.get("path"));
errorCode = "404 Not Found";
map.put(MESSAGE, "NOT FOUND");
break;
case METHOD_NOT_ALLOWED:
logger.error("Invalid HTTP Method type for the url: {}", map.get("path"));
errorCode = "405 Method Not Allowed";
break;
default:
logger.error("Unexpected error happened");
logger.error("errorstatus is : {}", errorStatus);
errorCode = "500 Internal Server Error";
map.put(MESSAGE, "Unexpected Error");
}
return errorCode;
}
}
The output will be something like below:
{
"status": 401,
"message": "Invalid Access Token",
"error_code": "401 UnAuthorized"
}