How to customize Spring boot controller API response for ZuulException - spring-boot

Question

We are using Zuul, Eureka and spring boot application services for REST APIs.
Suppose my spring boot service is down and when I tried to access the API using Zuul API gateway, I am getting ZuulException and response is below :
{
"timestamp": "2018-10-12T14:29:09.632+0000",
"status": 500,
"error": "Internal Server Error",
"exception": "com.netflix.zuul.exception.ZuulException",
"message": "GENERAL"
}
I want to customize the response format like below:
{
"success": false,
"message": "Service is down. Please try later"
}
I tried to implement https://stackoverflow.com/a/39841785/5506061 but its not working for me.
Please suggest how to customize the response for ZuulException.

Answer 1

You can implement your own FallbackProvider and customize the response based on the cause if needed.
Something like :
#Component
public class CustomFallbackBasedOnCause implements FallbackProvider {
private static final String DEFAULT_MSG = "{\"success\": false,\"message\": \"Service is down. Please try later\"}";
#Override
public String getRoute() {
return "*"; // * = all routes
}
#Override
public ClientHttpResponse fallbackResponse(final Throwable cause) {
if (cause instanceof HystrixTimeoutException) {
return response(HttpStatus.GATEWAY_TIMEOUT);
} else {
return fallbackResponse();
}
}
#Override
public ClientHttpResponse fallbackResponse() {
return response(HttpStatus.INTERNAL_SERVER_ERROR);
}
private ClientHttpResponse response(final HttpStatus status) {
return new ClientHttpResponse() {
#Override
public HttpStatus getStatusCode() throws IOException {
return status;
}
#Override
public int getRawStatusCode() throws IOException {
return status.value();
}
#Override
public String getStatusText() throws IOException {
return status.getReasonPhrase();
}
#Override
public void close() {
}
#Override
public InputStream getBody() throws IOException {
return new ByteArrayInputStream(DEFAULT_MSG.getBytes());
}
#Override
public HttpHeaders getHeaders() {
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
return headers;
}
};
}
}
As you can see in the getRoute() method, you can specify if this customFallback will be used for all routes (return "*") or for a specific route.
In case you work with Registry service (e.g Eureka). You don’t specify the route URL but the service id instead. return "SERVICEID"