배포 전략 — Blue-Green, Canary, Rolling Deployment 무중단 배포의 기술

# green-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: app-green
spec:
  replicas: 5
  selector:
    matchLabels:
      app: myapp
      version: v1.1
  template:
    metadata:
      labels:
        app: myapp
        version: v1.1
    spec:
      containers:
      - name: myapp
        image: myapp:v1.1

# 1. Blue 환경 실행 중 (기존)
$ kubectl get pods -l version=v1.0
myapp-v1.0-xxx  Running
 
# 2. Green 환경 준비
$ kubectl apply -f green-deployment.yaml
$ kubectl get pods -l version=v1.1
myapp-v1.1-xxx  Running
 
# 3. 테스트 (Green 환경으로 직접 요청)
$ kubectl port-forward svc/app-green 8000:8000
# http://localhost:8000 접속 → 정상 작동 확인
 
# 4. Service가 Green을 가리키도록 변경
$ kubectl patch service myapp -p '{"spec":{"selector":{"version":"v1.1"}}}'
 
# 5. 모든 트래픽이 Green으로 전환됨
 
# 6. Blue 유지 (빠른 롤백용)
# 문제 발생 시: kubectl patch service myapp -p '{"spec":{"selector":{"version":"v1.0"}}}'
 
# 7. 안정화 후 Blue 삭제
$ kubectl delete deployment app-blue

# Virtual Service: 트래픽 분배
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: myapp
spec:
  hosts:
  - myapp
  http:
  - match:
    - uri:
        prefix: /
    route:
    - destination:
        host: myapp
        subset: v1-0
      weight: 90        # v1.0: 90%
    - destination:
        host: myapp
        subset: v1-1
      weight: 10        # v1.1: 10%
  timeout: 30s
 
---
# Destination Rule: Pod 분류
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: myapp
spec:
  host: myapp
  subsets:
  - name: v1-0
    labels:
      version: v1.0
  - name: v1-1
    labels:
      version: v1.1

# 1. v1.0 Pod 5개 실행 (기존)
$ kubectl apply -f deployment-v1.0.yaml
 
# 2. v1.1 Pod 1개 추가
$ kubectl apply -f deployment-v1.1.yaml
 
# 3. Istio Virtual Service로 90:10 트래픽 분배
$ kubectl apply -f canary-vs.yaml
 
# 4. 모니터링 (예: Prometheus)
# 에러율: v1.0 < 0.1%, v1.1 < 0.5% → OK
# 응답시간: v1.0 = 50ms, v1.1 = 48ms → OK
 
# 5. 트래픽 비율 증가 (수동 또는 자동)
# 90:10 → 70:30 → 50:50 → 30:70 → 0:100
 
# 6. v1.0 삭제
$ kubectl delete deployment myapp-v1.0

# deployment.yaml (기본값)
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  replicas: 5
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1        # 동시에 추가할 Pod 수
      maxUnavailable: 1  # 동시에 내릴 Pod 수
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
    spec:
      containers:
      - name: myapp
        image: myapp:v1.1  # 새 이미지로 업데이트

# 1. 이미지만 변경 (Kubernetes가 자동으로 Rolling 시작)
$ kubectl set image deployment/myapp myapp=myapp:v1.1
 
# 2. 배포 진행 상황 확인
$ kubectl rollout status deployment/myapp
Waiting for rollout to finish: 3 out of 5 new replicas have been updated...
 
# 3. 배포 완료
$ kubectl get pods
myapp-v1.1-xxx  Running
myapp-v1.1-yyy  Running
myapp-v1.1-zzz  Running
myapp-v1.1-aaa  Running
myapp-v1.1-bbb  Running
 
# 4. 문제 발생 시 즉시 롤백
$ kubectl rollout undo deployment/myapp

# .github/workflows/deploy.yml
name: Deploy Blue-Green
 
on:
  push:
    branches:
      - main
 
jobs:
  deploy:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v3
    
    - name: Build and Push Docker Image
      run: |
        docker build -t myapp:${{ github.sha }} .
        docker push myapp:${{ github.sha }}
    
    - name: Deploy Green Environment
      run: |
        kubectl set image deployment/app-green myapp=myapp:${{ github.sha }}
        kubectl rollout status deployment/app-green
    
    - name: Test Green Environment
      run: |
        kubectl port-forward svc/app-green 8000:8000 &
        sleep 5
        curl http://localhost:8000/health || exit 1
    
    - name: Switch Traffic to Green
      if: success()
      run: |
        kubectl patch service myapp -p '{"spec":{"selector":{"version":"v1.1"}}}'
    
    - name: Rollback to Blue if Failed
      if: failure()
      run: |
        kubectl patch service myapp -p '{"spec":{"selector":{"version":"v1.0"}}}'