Eureka: 서비스 디스커버리

// build.gradle
implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-server'

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApplication.class, args);
    }
}

# application.yml
server:
  port: 8761

spring:
  application:
    name: eureka-server

eureka:
  instance:
    hostname: localhost
  client:
    register-with-eureka: false
    fetch-registry: false

implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-client'

@SpringBootApplication
@EnableEurekaClient  // 또는 @EnableDiscoveryClient
public class UserServiceApplication { }

spring:
  application:
    name: user-service

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
  instance:
    prefer-ip-address: true
    instance-id: ${spring.application.name}:${random.uuid}

@Configuration
public class RestConfig {

    @Bean
    @LoadBalanced  // Eureka에서 인스턴스 자동 발견
    public RestTemplate restTemplate() {
        return new RestTemplate();
    }
}


@Service
@RequiredArgsConstructor
public class OrderService {
    private final RestTemplate restTemplate;

    public ProductDto getProduct(Long productId) {
        // 서비스 이름으로 호출 — Eureka가 IP 자동 해결
        return restTemplate.getForObject(
            "http://product-service/products/" + productId,
            ProductDto.class
        );
    }
}

http://localhost:8761/

표시:
- 등록된 서비스 목록
- 각 서비스의 인스턴스 수
- 인스턴스 상태 (UP/DOWN)
- 메타데이터 (port, version)

eureka:
  instance:
    lease-renewal-interval-in-seconds: 30  # 30초마다 하트비트
    lease-expiration-duration-in-seconds: 90  # 90초 후 제거

# 3개 Eureka 서버 클러스터
# eureka1.yml
spring:
  application:
    name: eureka-server
eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://eureka2:8761/eureka/,http://eureka3:8761/eureka/

// Netflix Eureka는 maintenance mode
// Spring Cloud LoadBalancer가 새 표준

// 사용은 거의 동일 — @LoadBalanced 자동 적용