Spring Cloud Hystrix：未调用FallbackMethod

Question

I am playing around Spring Cloud Hystrix and I got this weird error that my Fallback method is not being invoked. My Controller is below .

@Controller
public class DashboardController {

    @LoadBalanced
    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder){
        return builder.build();
    }

    @Autowired
    private RestTemplate restTemplate;

    @HystrixCommand(fallbackMethod = "getFareBackup")
    @RequestMapping("/dashboard")
    public String getFareDashboard(Model m) {
        try {
            ResponseEntity<List<BusFare>> responseEntity = restTemplate.exchange("http://busfare-service/api/v1/fare/",
                    HttpMethod.GET, null, new ParameterizedTypeReference<List<BusFare>>() {
                    });
            m.addAttribute("fareList", responseEntity.getBody());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "dashboard";
    }


    public String getFareBackup(Model m){
        System.out.println("Fallback operation called");

        m.addAttribute("fareList", new ArrayList<BusFare>().add(new BusFare(1, BigDecimal.valueOf(0.7), "Regular")));
        return "dashboard";
    }

}

As you can see, I set the fallbackMethod properly, however, when I run the server and point my browser to the end point, I get an exception saying that my server is down, as I understand when my service is down it should invoke the fallbackMethod, but it in my case that is not the case, my fallbackMethod is basically not being invoked.

java.lang.IllegalStateException: No instances available for busfare-service

I am missing something in my code?

Answer 1

It seems my like, Hystrix handles this fallbackMethod thru errorHandling. What messed up my code that caused my fallback not being invoked is the errorHandling.

@HystrixCommand(fallbackMethod = "getFareBackup")
@RequestMapping("/dashboard")
public String getFareDashboard(Model m) {

    ResponseEntity<List<BusFare>> responseEntity = restTemplate.exchange("http://busfare-service/api/v1/fare/",
                HttpMethod.GET, null, new ParameterizedTypeReference<List<BusFare>>() {
                });

    m.addAttribute("fareList", responseEntity.getBody());

    return "dashboard";
}

With the code above, the fallbackMethod is now working.