Spring Cloud Config — 분산 환경에서 설정을 중앙 관리하는 방법

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-config-server</artifactId>
</dependency>

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

# application.yml (Config Server)
server:
  port: 8888

spring:
  cloud:
    config:
      server:
        git:
          uri: https://github.com/my-org/config-repo
          default-label: main
          search-paths: '{application}'  # 애플리케이션별 디렉토리
          clone-on-start: true           # 시작 시 clone

config-repo/
├── application.yml          # 모든 서비스 공통 설정
├── order-service/
│   ├── application.yml      # order-service 기본 설정
│   └── application-prod.yml # order-service 운영 설정
├── payment-service/
│   ├── application.yml
│   └── application-prod.yml
└── user-service/
    ├── application.yml
    └── application-prod.yml

GET /{application}/{profile}
GET /{application}/{profile}/{label}

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-config</artifactId>
</dependency>

# application.yml (각 서비스)
spring:
  application:
    name: order-service  # Config Server에서 이 이름으로 설정을 찾음
  config:
    import: configserver:http://localhost:8888
  cloud:
    config:
      fail-fast: true    # Config Server 연결 실패 시 즉시 종료
      retry:
        initial-interval: 1000
        max-attempts: 5

@RestController
@RefreshScope  // refresh 시 빈이 재생성됨
public class FeatureController {

    @Value("${feature.new-ui-enabled:false}")
    private boolean newUiEnabled;

    @Value("${app.notification.email:admin@example.com}")
    private String notificationEmail;

    @GetMapping("/feature-flags")
    public Map<String, Object> getFeatureFlags() {
        return Map.of(
                "newUiEnabled", newUiEnabled,
                "notificationEmail", notificationEmail
        );
    }
}

# Actuator의 refresh 엔드포인트 호출
curl -X POST http://order-service:8080/actuator/refresh

# Actuator 설정 (클라이언트)
management:
  endpoints:
    web:
      exposure:
        include: refresh, health

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-bus-amqp</artifactId>  <!-- RabbitMQ -->
</dependency>

# 한 번의 요청으로 모든 인스턴스에 전파
curl -X POST http://any-instance:8080/actuator/busrefresh

[Config Server] → Git 변경 감지
       ↓
[/actuator/busrefresh 호출]
       ↓
[RabbitMQ] → 이벤트 전파
       ↓
[order-service-1] [order-service-2] [order-service-3]
  (설정 갱신)        (설정 갱신)        (설정 갱신)

Git Push → Webhook → /monitor 엔드포인트 → Bus 이벤트 → 전체 인스턴스 갱신

# Config Server
encrypt:
  key: my-secret-encryption-key

# 암호화
curl -X POST http://config-server:8888/encrypt -d "db-password-123"
# → 682bc583f4641332b5bb3e7...

# 복호화
curl -X POST http://config-server:8888/decrypt -d "682bc583f4641332b5bb3e7..."
# → db-password-123

# Git 저장소의 설정 파일
spring:
  datasource:
    password: '{cipher}682bc583f4641332b5bb3e7...'

spring:
  cloud:
    config:
      server:
        vault:
          host: vault.example.com
          port: 8200
          scheme: https
          authentication: TOKEN
          token: s.my-vault-token

# application.yml (기본, 모든 환경)
app:
  name: order-service
  log-level: INFO

# application-dev.yml (개발)
spring:
  datasource:
    url: jdbc:h2:mem:devdb

# application-prod.yml (운영)
spring:
  datasource:
    url: jdbc:mysql://prod-db:3306/orders
    password: '{cipher}...'