How can microservice can talk to other microservice in JHipster

Question

I am planning to create a microservice aplication with a dedicated service for dealing with data (mostly a Mongodb based service). I am wondering if there is a way using which my other microservices will be able to communicate with this service to make use of the shared data. Is it possible with JHipster API Gateway ? If not how can I achieve this. I dont want to keep multiple copies of the same data within each microservice.

Answer 1

You can also use Feign clients with JHipster.

Annotate your SpringBootApplication with @EnableFeignClients

...
import org.springframework.cloud.openfeign.EnableFeignClients;
...
@SpringBootApplication
@EnableConfigurationProperties({LiquibaseProperties.class, ApplicationProperties.class})
@EnableDiscoveryClient
@EnableFeignClients
public class MyApp {
    ...
}

Create a Feign client in your microservice

...
import org.springframework.cloud.openfeign.FeignClient;
...
@FeignClient("another-service")
public interface AnotherClient {

    @RequestMapping(method = RequestMethod.GET, value = "/api/another")
    List<AnotherDTO> getAll();
}

Inject the Feign client with @Autowired and call it. It should be ready to use.

@RestController
@RequestMapping("/api")
public class MyResource {
    ...
    @Autowired
    private AnotherClient anotherClient;
    ...
    @GetMapping("/another")
    @Timed
    public List<AnotherDTO> getAll() {
        log.debug("REST request to get all");
        return anotherClient.getAll();
    }
}

For us, it worked without implementing a ClientHttpRequestInterceptor and setting a JWT token.

Answer 2

You can register your microservices to the same registry and then they can call each other.

UPDATE : Here is how I made it work. In the microservice consuming the data one, use RestTemplate with the current user's jwt-token in the Authorization-header for the API calls :

@Component
public class AuthenticateClientHttpRequestInterceptor implements ClientHttpRequestInterceptor {

    @Override
    public ClientHttpResponse intercept(HttpRequest httpRequest, byte[] bytes, ClientHttpRequestExecution clientHttpRequestExecution) throws IOException {
        String token = SecurityUtils.getCurrentUserJWT();
        httpRequest.getHeaders().add("Authorization","Bearer "+token);
        return clientHttpRequestExecution.execute( httpRequest, bytes );
    }
}

My custom restTemplate using ClientHttpRequestInterceptor for adding token in header.

@Configuration
public class CustomBean {
    @Autowired
    AuthenticateClientHttpRequestInterceptor interceptor;
    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.setInterceptors(Collections.singletonList(interceptor));
        return restTemplate;
    }
}

And in the resource controller where your are making the call for data:

@RestController
@RequestMapping("/api")
public class DataResource {    
    @Autowired
    RestTemplate restTemplate;

            @PostMapping("/hello")
            @Timed
            public ResponseEntity<Hello> createHello(@RequestBody Hello Hello) throws URISyntaxException {
                
    //The name your data micro service registrated in the Jhipster Registry
                String dataServiceName = "data_micro_service";
            
                URI uri = UriComponentsBuilder.fromUriString("//" + dataServiceName + "/api/datas")
                    .build()
                    .toUri();
            
                //call the data microservice apis
                List<Data> result = restTemplate.getForObject(uri, Data[].class);
            
            
            return ResponseEntity.created(new URI("/api/hellos/" + result.getId()))
                    .headers(HeaderUtil.createEntityCreationAlert(ENTITY_NAME, result.getId().toString()))
                    .body(result);
        
        }

}