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springspring-cloudspring-cloud-netflixnetflix-ribbon

@LoadBalanced RestTemplate to call nested context endpoints

The below guide page is great and works as a base case for ribbon in a spring boot application.

https://spring.io/guides/gs/client-side-load-balancing/

The example stops working as soon as the endpoint mappings become nested - e.g. adding

@RequestMapping(value = "/welcome")

at the class level

@RestController
@SpringBootApplication
@RequestMapping(value = "/welcome") //<------------- ADDED --->
public class SayHelloApplication {

  private static Logger log = LoggerFactory.getLogger(SayHelloApplication.class);

  @RequestMapping(value = "/greeting")
  public String greet() {

And then change the @LoadBalanced RestTemplate call in the client from

String greeting = this.restTemplate.getForObject("http://say-hello/greeting", String.class);

to 

String greeting = this.restTemplate.getForObject("http://say-hello/welcome/greeting", String.class);

Calls are failing with attached stacktrace while directly acessing http://localhost:8090/welcome/greeting still works fine. What would be the appropriate way to configure ribbon to load balance requests to long and nested URL endpoints such as domain.com/x/y/z/p/q?

Stacktrace:

java.lang.IllegalStateException: No instances available for say-hello
    at org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient.execute(RibbonLoadBalancerClient.java:79) ~[spring-cloud-netflix-core-1.1.4.RELEASE.jar:1.1.4.RELEASE]
    at org.springframework.cloud.client.loadbalancer.LoadBalancerInterceptor.intercept(LoadBalancerInterceptor.java:46) ~[spring-cloud-commons-1.1.1.RELEASE.jar:1.1.1.RELEASE]
    at org.springframework.http.client.InterceptingClientHttpRequest$InterceptingRequestExecution.execute(InterceptingClientHttpRequest.java:85) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.http.client.InterceptingClientHttpRequest.executeInternal(InterceptingClientHttpRequest.java:69) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.http.client.AbstractBufferingClientHttpRequest.executeInternal(AbstractBufferingClientHttpRequest.java:48) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.http.client.AbstractClientHttpRequest.execute(AbstractClientHttpRequest.java:53) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:596) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:557) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.web.client.RestTemplate.getForObject(RestTemplate.java:264) ~[spring-web-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at hello.UserApplication.hi(UserApplication.java:31) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_45]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_45]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_45]
    at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_45]
Solution

  • The issue is by adding @RequestMapping to the class you also changed the / handler to move from the root to /welcome/. To make it so the load balancer can keep working you have to update the PingUrl being used within the SayHelloConfiguration of the user app. Make it new PingUrl(false, "/welcome/")