PersistentVolume

# PersistentVolume 정의 (관리자가 생성)
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-database
  labels:
    type: ssd
spec:
  capacity:
    storage: 100Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: fast-ssd
  # AWS EBS 사용 예시
  awsElasticBlockStore:
    volumeID: vol-0abc123def456
    fsType: ext4

---
# PersistentVolumeClaim (개발자가 요청)
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: database-pvc
  namespace: production
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: fast-ssd
  resources:
    requests:
      storage: 50Gi  # PV 용량 이하로 요청
  selector:
    matchLabels:
      type: ssd

---
# Pod에서 PVC 사용
apiVersion: v1
kind: Pod
metadata:
  name: postgres
spec:
  containers:
    - name: postgres
      image: postgres:15
      volumeMounts:
        - name: data
          mountPath: /var/lib/postgresql/data
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: database-pvc

# StorageClass - 동적 프로비저닝
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: ebs.csi.aws.com  # AWS EBS CSI 드라이버
parameters:
  type: gp3
  iops: "3000"
  throughput: "125"
  encrypted: "true"
  fsType: ext4
reclaimPolicy: Delete
allowVolumeExpansion: true  # 볼륨 확장 허용
volumeBindingMode: WaitForFirstConsumer  # Pod 스케줄링 시 바인딩

---
# GCP용 StorageClass
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gcp-ssd
provisioner: pd.csi.storage.gke.io
parameters:
  type: pd-ssd
  replication-type: regional-pd  # 멀티 AZ 복제
reclaimPolicy: Retain
allowVolumeExpansion: true

---
# NFS용 StorageClass (RWX 지원)
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-storage
provisioner: nfs.csi.k8s.io
parameters:
  server: nfs-server.example.com
  share: /exports/kubernetes
reclaimPolicy: Delete

# StatefulSet - 상태 유지 애플리케이션 (DB, Kafka 등)
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: postgres
  namespace: production
spec:
  serviceName: postgres
  replicas: 3
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
        - name: postgres
          image: postgres:15
          ports:
            - containerPort: 5432
          env:
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: postgres-secret
                  key: password
          volumeMounts:
            - name: data
              mountPath: /var/lib/postgresql/data
          resources:
            requests:
              memory: "1Gi"
              cpu: "500m"
            limits:
              memory: "2Gi"
              cpu: "1000m"
  # volumeClaimTemplates - 각 Pod에 개별 PVC 생성
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: ["ReadWriteOnce"]
        storageClassName: fast-ssd
        resources:
          requests:
            storage: 100Gi

# 결과: postgres-0, postgres-1, postgres-2 각각
# data-postgres-0, data-postgres-1, data-postgres-2 PVC 생성