Spring Cloud Service Discovery - Netflix Eureka (2)

전체 내용은 Github에 있습니다 :)

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Netflix Eureka Server HA

이전 포스팅에서 Eureka에 대한 개요를 살펴보았다.

이번엔 Eureka Server에서 HA 구성을 어떻게 하는지 살펴보자.

Peer Awareness

1. Eureka Cluster에서 Eureka Server는 peer 라고 표현하고 아래와 같은 행위를 Peer Awareness라고 부른다.
2. 각각의 Eureka Server는 Eureka Client를 이용하여 Register와 Fetch Registry 작업이 이루어진다.
3. 또한 Register, Renew 등 모든 Operation이 발생하면 다른 Peer에게 동일한 요청을 시도한다.

아래와 같이 PeerAwareInstanceRegistryImpl를 살펴보자.

Register 요청에 대하여 자신의 Registry를 업데이트하고 replicateToPeers() 를 통해 다른 Peer에게
Register with replica 요청을 보낸다.(즉 POST /eureka/v2/apps/appID 요청과 헤더에 Replica 속성을 true)

@Singleton
public class PeerAwareInstanceRegistryImpl extends AbstractInstanceRegistry implements PeerAwareInstanceRegistry {
    ...
    @Override
    public void register(final InstanceInfo info, final boolean isReplication) {
        int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS;
        if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) {
            leaseDuration = info.getLeaseInfo().getDurationInSecs();
        }
        super.register(info, leaseDuration, isReplication);
        replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication);
    }
    ...
}

Eureka Server HA 구성하기

아래와 같이 Spring Profile 속성을 활용하여 peer1-3을 구성해보자

application.yaml

---

spring:
  profiles: peer-1
  application:
    name: eureka-server-clustered
server:
  port: 3001
eureka:
  instance:
    hostname: peer-1-server.com
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://localhost:3002/eureka/,http://localhost:3003/eureka/

---

spring:
  profiles: peer-2
  application:
    name: eureka-server-clustered
server:
  port: 3002
eureka:
  instance:
    hostname: peer-2-server.com
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://localhost:3001/eureka/,http://localhost:3003/eureka/

---

spring:
  profiles: peer-3
  application:
    name: eureka-server-clustered
server:
  port: 3003
eureka:
  instance:
    hostname: peer-3-server.com
  client:
    registerWithEureka: true
    fetchRegistry: true
    serviceUrl:
      defaultZone: http://localhost:3001/eureka/,http://localhost:3002/eureka/

docker-compose를 이용하여 3개의 Server를 실행하자

docker-compose.yaml

version: '3.1'

services:
  eureka-peer-1:
    build:
      context: ../../eureka-server
      dockerfile: Dockerfile
    image: service-discovery/eureka-server
    hostname: eureka-peer-1
    container_name: eureka-peer-1
    ports:
      - 3001:3001
    environment:
      - SPRING_PROFILES_ACTIVE=peer-1
      - EUREKA_CLIENT_SERVICE-URL_DEFAULT-ZONE=http://eureka-peer-2:3002/eureka/,http://eureka-peer-3:3003/eureka/
  eureka-peer-2:
    image: service-discovery/eureka-server
    hostname: eureka-peer-2
    container_name: eureka-peer-2
    ports:
      - 3002:3002
    environment:
      - SPRING_PROFILES_ACTIVE=peer-2
      - EUREKA_CLIENT_SERVICE-URL_DEFAULT-ZONE=http://eureka-peer-1:3001/eureka/,http://eureka-peer-3:3003/eureka/
  eureka-peer-3:
    image: service-discovery/eureka-server
    hostname: eureka-peer-3
    container_name: eureka-peer-3
    ports:
      - 3003:3003
    environment:
      - SPRING_PROFILES_ACTIVE=peer-3
      - EUREKA_CLIENT_SERVICE-URL_DEFAULT-ZONE=http://eureka-peer-1:3001/eureka/,http://eureka-peer-2:3002/eureka/

  account-service:
    build:
      context: ../../account
      dockerfile: Dockerfile
    image: service-discovery/account
    container_name: account-service
    restart: always
    environment:
      - STARTUP_WAIT=5
      - EUREKA_CLIENT_SERVICE-URL_DEFAULT-ZONE=http://eureka-peer-1:3001/eureka/,http://eureka-peer-2:3002/eureka/,http://eureka-peer-3:3003/eureka/
    ports:
      - 3100:3100
    depends_on:
      - eureka-peer-1
      - eureka-peer-2
      - eureka-peer-3

  article-service:
    build:
      context: ../../article
      dockerfile: Dockerfile
    image: service-discovery/article
    container_name: article-service
    restart: always
    environment:
      - STARTUP_WAIT=5
      - EUREKA_CLIENT_SERVICE-URL_DEFAULT-ZONE=http://eureka-peer-1:3001/eureka/,http://eureka-peer-2:3002/eureka/,http://eureka-peer-3:3003/eureka/
    ports:
      - 3200:3200
    depends_on:
      - eureka-peer-1
      - eureka-peer-2
      - eureka-peer-3
      - account-service