MS - Call rest service to service call Step2; Call with Autowired RestTemplate object

 Earlier we just made a RestTemplate object and call the other rest-service using "getForObject" method providing url and response type

//Phase 1 - without Discovery/Eureka client
Greet greet = restTemplate.getForObject("http://localhost:8090/greet", Greet.class);

Here Problems

1. URL is hard coded and also port --> Better if we can call with service name -->What we need to do

Solution

1. who knows the service-name ?

1.1 Discovery server has the 'service-name', so we configure the rest-client service with discovery-server making rest-client service as client for Discovery server. @EnableDiscoveryClient

2. Make RestTemplate Autowired and Load balanced

Now Step2: 

1. Make RestTemplate @Autowored

2. To make it Autowired, we need to create the bean of RestTemplate object. 

2.1 So here we create a bean inside Springboot main class 

2.2 make it @LoadBalanced

3. To find the service add @EnableDiscoveryClient for the main class and discovery client dependency

3.1 add Eureka client dependency

    3.1.1 when added dependency - add properties configure version

    3.1.2 add dependency management

3.2 add eureka client properties to configure

Below are the code blocks with changes

Main Class

package com.example.rest_client;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
@EnableDiscoveryClient
public class RestClientApplication {

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

    @LoadBalanced
    @Bean
    public RestTemplate restTemplate(){
       return new RestTemplate();
    }
}

Controller class

package com.example.rest_client.controller;

import com.example.rest_client.model.Greet;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

@RestController
public class GreetClientController {

//    private RestTemplate restTemplate = new RestTemplate();
    @Autowired
    private RestTemplate restTemplate;

    @RequestMapping("/greet-call")
    Greet greet() {
        //Phase 1 - without Discovery/Eureka client
//        Greet greet = restTemplate.getForObject("http://localhost:8090/greet", Greet.class);
//With Discovery client - Now we can use service name - and with other option available via eureka server
        // you need to configure DiscoveryClient - else cannot find hte hostname "greet-service" which is registered inEureka server
        Greet greet = restTemplate.getForObject("http://greet-service/greet", Greet.class);
        return greet;
    }
}

application properties

spring.application.name=rest-client
server.port=8095

#phase 2 - add eureka
eureka.client.serviceUrl.defaultZone= http://localhost:8761/eureka/

POM

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
</dependency>

When you add the above dependency you need to configure the version in the properties and the dependency management

<properties>
    
    <spring-cloud.version>2025.0.0</spring-cloud.version>
</properties>

<!--    added dependency mgt after adding discovery client dependency-->
    <dependencyManagement>
       <dependencies>
          <dependency>
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-dependencies</artifactId>
             <version>${spring-cloud.version}</version>
             <type>pom</type>
             <scope>import</scope>
          </dependency>
       </dependencies>
    </dependencyManagement>