Can we call Zuul enabled server through RestTemplate

Question

I am trying to call a zuul enabled server through RestTemplate by directly giving the URL. For example: restTemplate.getForObject("http://localhost:8090/emp-api", Employee[].class);

But it is giving an error to me:

java.lang.IllegalStateException: No instances available for localhost at org.springframework.cloud.netflix.ribbon.RibbonLoadBalancerClient.execute(RibbonLoadBalancerClient.java:90) ~[spring-cloud-netflix-core-1.2.3.RELEASE.jar:1.2.3.RELEASE]

Question in detail : I am having four projects (Github link (branch-master): https://github.com/vickygupta0017/microservice-poc)

1. microservice-server (eureka-server) port:8080
2. microservice-producer (Rest-api) port:8086
3. zuul-gatewayproxy (zuul-server) port:8090

4. microservice-consumer (spring-mvc) port:8087

   

If I am calling zuul server directly from browser("http://localhost:8090/emp-api), then it is redirecting the request to producer successfully. But if I am calling this URL from the consumer through RestTemplate then it is giving me this error.

For Information : If I am not using zuul sever then I am able to call 'microservice-producer' from 'microservice-consumer' using RestTemplate successfully.

Answer 1

I had successfully executed your code with below changes, removed the

enablediscovery and LoadBalanced annotation

if this will be enabled then always rest template will go to eureka for discovery, as you are using proxy server then your consumer don't need the discovery because you are giving absolute path also remove eureka configurations from application.yml.

You cannot use discovery and absolute path at the same time, only one can be used at a time.

package com.eureka.discovery.client;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import com.eureka.discovery.client.bo.Employee;

@SpringBootApplication
@RestController
//@EnableDiscoveryClient
public class UserApplication {

  @Bean
//@Loadbalancer
  RestTemplate restTemplate(){
    return new RestTemplate();
  }

  @Autowired
  RestTemplate restTemplate;

  @RequestMapping("/hi")
  public String hi() {
      Employee[] employeeList = this.restTemplate.getForObject("http://localhost:8090/emp-api", Employee[].class);
    return String.format("%s, %s!", "Testing", "Abhay");
  }

  public static void main(String[] args) {
    SpringApplication.run(UserApplication.class, args);
  }
}

Answer 2

The RestTemplate instance might have been configured to lookup the service localhost via Eureka instead of assuming http://localhost:.... is already the URL

Answer 3

If you are calling the services with ip and port then there is no need of Eureka, As you are doing inter micro service communication and eureka is already in picture for service discovery and registry. You want to do load balancing then zuul will come in picture.

Change your code in consumer with mricroservice name instead of ip and port then it will work.

@SpringBootApplication
@EnableDiscoveryClient
public class WebclientConsumerMicroserviceApplication {

    public static final String EMPLOYEE_SERVICE_URL = "http://employee-microservice/";

and also change the remaining uri in employeeServicesImpl.

    public List<Employee> getEmployeeList() {
//  Employee[] employeeList =  restTemplate.getForObject("http://employee-microservice/employees", Employee[].class);
    Employee[] employeeList =  restTemplate.getForObject(url+"employees, Employee[].class);

It will be working Just start this way :

1. Start your Eureka
2. Start the Producer Service
3. Start the Consumer Service and it will be workable.

Note : We need to call the services only via service name and needs to avoid ip and port(they are dynamic).

If you want to run using zuul then use the zuul service name : zuul-gateway with below configuration in consumer

zuul-gateway:
  ribbon:
    eureka:
      enabled: false
    listOfServers: localhost:8090
    ServerListRefreshInterval: 1500