컨테이너 오케스트레이션: K8s 기초

Pod: 컨테이너 1+ 묶음 (가장 작은 배포 단위)
ReplicaSet: Pod 복제본 관리
Deployment: 선언적 업데이트·롤백
Service: 네트워크 추상화 (안정적 endpoint)
Ingress: 외부 트래픽 라우팅
ConfigMap/Secret: 설정·시크릿 분리
Namespace: 논리적 격리

# ohs-backend-deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: ohs-backend
  labels:
    app: ohs-backend
spec:
  replicas: 3
  selector:
    matchLabels:
      app: ohs-backend
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 0
  template:
    metadata:
      labels:
        app: ohs-backend
    spec:
      containers:
        - name: app
          image: myorg/ohs-backend:1.0.0
          ports:
            - containerPort: 8080
          env:
            - name: SPRING_PROFILES_ACTIVE
              value: prod
            - name: DB_URL
              valueFrom:
                secretKeyRef:
                  name: ohs-secrets
                  key: db-url
          resources:
            requests:
              memory: "512Mi"
              cpu: "250m"
            limits:
              memory: "1Gi"
              cpu: "1000m"
          livenessProbe:
            httpGet:
              path: /actuator/health/liveness
              port: 8080
            initialDelaySeconds: 60
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /actuator/health/readiness
              port: 8080
            initialDelaySeconds: 30
            periodSeconds: 5

apiVersion: v1
kind: Service
metadata:
  name: ohs-backend
spec:
  type: ClusterIP  # 내부만 (Pod IP는 변하므로 안정적 endpoint)
  ports:
    - port: 80
      targetPort: 8080
  selector:
    app: ohs-backend

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ohs-ingress
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt
spec:
  tls:
    - hosts:
        - api.openhyperstep.com
      secretName: ohs-tls
  rules:
    - host: api.openhyperstep.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: ohs-backend
                port:
                  number: 80

apiVersion: v1
kind: ConfigMap
metadata:
  name: ohs-config
data:
  application.yml: |
    server:
      port: 8080
    spring:
      jpa:
        hibernate:
          ddl-auto: validate

# Secret 생성
kubectl create secret generic ohs-secrets \
    --from-literal=db-password=mypassword \
    --from-literal=jwt-secret=$(openssl rand -base64 32)

# 적용
kubectl apply -f deployment.yml

# 조회
kubectl get pods
kubectl get svc
kubectl get deployments

# 상세
kubectl describe pod <pod-name>

# 로그
kubectl logs <pod-name>
kubectl logs -f deployment/ohs-backend

# 디버깅
kubectl exec -it <pod-name> -- /bin/sh

# 스케일
kubectl scale deployment ohs-backend --replicas=5

# 롤링 업데이트
kubectl set image deployment/ohs-backend app=myorg/ohs-backend:1.1.0

# 롤백
kubectl rollout undo deployment/ohs-backend

# 삭제
kubectl delete -f deployment.yml

apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: ohs-backend-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: ohs-backend
  minReplicas: 3
  maxReplicas: 20
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 70