Storage

# 원본 파일: 이미지 레이어에 존재
/app/config.yaml  (읽기 전용)

# 컨테이너에서 수정 시도
echo "new: value" >> /app/config.yaml

# 실제 동작:
# 1. /app/config.yaml을 Container Layer로 복사
# 2. 복사본을 수정
# 3. 원본은 그대로 유지

# 볼륨 생성
docker volume create data_volume

# 볼륨 마운트 (Volume Mount)
docker run -v data_volume:/var/lib/mysql mysql

# 호스트 경로 마운트 (Bind Mount)
docker run -v /data/mysql:/var/lib/mysql mysql

# 최신 문법 (--mount)
docker run --mount type=volume,source=data_volume,target=/var/lib/mysql mysql
docker run --mount type=bind,source=/data/mysql,target=/var/lib/mysql mysql

# 문제 상황: 데이터 손실
apiVersion: v1
kind: Pod
metadata:
  name: data-processor
spec:
  containers:
  - name: processor
    image: alpine
    command: ["/bin/sh", "-c"]
    args: ["shuf -i 1-100 -n 1 >> /opt/result.txt; sleep 3600"]
    # Pod 삭제 시 /opt/result.txt 손실

apiVersion: v1
kind: Pod
metadata:
  name: data-processor
spec:
  containers:
  - name: processor
    image: alpine
    command: ["/bin/sh", "-c"]
    args: ["shuf -i 1-100 -n 1 >> /opt/result.txt; sleep 3600"]
    volumeMounts:
    - name: data-volume
      mountPath: /opt
  volumes:
  - name: data-volume
    hostPath:
      path: /data
      type: DirectoryOrCreate

apiVersion: v1
kind: Pod
metadata:
  name: multi-container
spec:
  containers:
  - name: writer
    image: busybox
    command: ["/bin/sh", "-c"]
    args: ["while true; do date >> /cache/timestamp.log; sleep 5; done"]
    volumeMounts:
    - name: cache
      mountPath: /cache
  - name: reader
    image: busybox
    command: ["/bin/sh", "-c"]
    args: ["tail -f /cache/timestamp.log"]
    volumeMounts:
    - name: cache
      mountPath: /cache
  volumes:
  - name: cache
    emptyDir:
      sizeLimit: 500Mi  # 크기 제한
      # medium: Memory  # RAM 기반 (tmpfs)

# AWS EBS
volumes:
- name: aws-volume
  awsElasticBlockStore:
    volumeID: vol-0123456789abcdef0
    fsType: ext4

# Azure Disk
volumes:
- name: azure-volume
  azureDisk:
    diskName: myDataDisk
    diskURI: /subscriptions/.../myDataDisk

# GCP Persistent Disk
volumes:
- name: gcp-volume
  gcePersistentDisk:
    pdName: my-data-disk
    fsType: ext4

# NFS
volumes:
- name: nfs-volume
  nfs:
    server: nfs-server.example.com
    path: /exports/data

# 모든 Pod에 스토리지 설정 반복
apiVersion: v1
kind: Pod
metadata:
  name: web-app
spec:
  volumes:
  - name: data
    awsElasticBlockStore:    # 매번 설정 필요
      volumeID: vol-xxx
      fsType: ext4

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-volume
  labels:
    type: local
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: manual
  hostPath:
    path: /mnt/data

# AWS EBS PV
apiVersion: v1
kind: PersistentVolume
metadata:
  name: aws-ebs-pv
spec:
  capacity:
    storage: 50Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: gp3
  awsElasticBlockStore:
    volumeID: vol-0123456789abcdef0
    fsType: ext4
---
# NFS PV
apiVersion: v1
kind: PersistentVolume
metadata:
  name: nfs-pv
spec:
  capacity:
    storage: 100Gi
  accessModes:
    - ReadWriteMany  # NFS는 RWX 지원
  persistentVolumeReclaimPolicy: Retain
  nfs:
    server: 192.168.1.100
    path: /exports/data

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: manual
  # selector:  # 특정 PV 선택 (선택적)
  #   matchLabels:
  #     type: local

# PV: 10Gi, RWO, manual class
# PVC: 5Gi 요청, RWO, manual class
# 결과: 바인딩 성공 (5Gi 사용, 5Gi 낭비)

apiVersion: v1
kind: Pod
metadata:
  name: web-server
spec:
  containers:
  - name: nginx
    image: nginx
    volumeMounts:
    - name: web-storage
      mountPath: /usr/share/nginx/html
  volumes:
  - name: web-storage
    persistentVolumeClaim:
      claimName: my-pvc

# PV 상태
kubectl get pv
# STATUS: Available → Bound → Released

# PVC 상태
kubectl get pvc
# STATUS: Pending → Bound

# 상세 정보
kubectl describe pv pv-volume
kubectl describe pvc my-pvc

# 기본 StorageClass
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-standard
reclaimPolicy: Delete
volumeBindingMode: Immediate
allowVolumeExpansion: true
---
# 고성능 StorageClass
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: kubernetes.io/gce-pd
parameters:
  type: pd-ssd
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true

# AWS EBS CSI
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: ebs-gp3
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  iops: "3000"
  throughput: "125"
  encrypted: "true"
volumeBindingMode: WaitForFirstConsumer
---
# Azure Disk CSI
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azure-premium
provisioner: disk.csi.azure.com
parameters:
  skuName: Premium_LRS
  kind: Managed
reclaimPolicy: Delete
---
# Local Path (개발용)
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: local-path
provisioner: rancher.io/local-path
reclaimPolicy: Delete
volumeBindingMode: WaitForFirstConsumer

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: database-pvc
spec:
  storageClassName: fast-ssd  # StorageClass 지정
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 50Gi

# 기본 StorageClass 확인
kubectl get sc

# 기본 StorageClass 설정
kubectl patch storageclass fast-ssd -p \
  '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'

# storageClassName 생략 시 기본 StorageClass 사용

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: mysql
  replicas: 3
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:8.0
        env:
        - name: MYSQL_ROOT_PASSWORD
          valueFrom:
            secretKeyRef:
              name: mysql-secret
              key: password
        volumeMounts:
        - name: mysql-data
          mountPath: /var/lib/mysql
  volumeClaimTemplates:  # 각 Pod에 개별 PVC 생성
  - metadata:
      name: mysql-data
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: fast-ssd
      resources:
        requests:
          storage: 10Gi

apiVersion: v1
kind: Pod
metadata:
  name: multi-volume-pod
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - name: config
      mountPath: /etc/nginx/conf.d
      readOnly: true
    - name: logs
      mountPath: /var/log/nginx
    - name: data
      mountPath: /usr/share/nginx/html
    - name: cache
      mountPath: /var/cache/nginx
  volumes:
  - name: config
    configMap:
      name: nginx-config
  - name: logs
    emptyDir: {}
  - name: data
    persistentVolumeClaim:
      claimName: web-content-pvc
  - name: cache
    emptyDir:
      medium: Memory
      sizeLimit: 256Mi

# VolumeSnapshotClass 정의
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-snapclass
driver: ebs.csi.aws.com
deletionPolicy: Delete
---
# 스냅샷 생성
apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: mysql-snapshot
spec:
  volumeSnapshotClassName: csi-snapclass
  source:
    persistentVolumeClaimName: mysql-pvc
---
# 스냅샷에서 PVC 복원
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-restore
spec:
  storageClassName: fast-ssd
  dataSource:
    name: mysql-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

# StorageClass에서 확장 허용
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: expandable-sc
provisioner: ebs.csi.aws.com
allowVolumeExpansion: true  # 필수
---
# PVC 크기 수정으로 확장
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: expandable-pvc
spec:
  storageClassName: expandable-sc
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi  # 10Gi → 20Gi로 수정

# PV 조회
kubectl get pv
kubectl get pv -o wide

# PVC 조회
kubectl get pvc
kubectl get pvc -A  # 모든 네임스페이스

# 상세 정보
kubectl describe pv pv-volume
kubectl describe pvc my-pvc

# PVC 삭제 (PV는 reclaimPolicy에 따라 처리)
kubectl delete pvc my-pvc

# StorageClass 조회
kubectl get sc
kubectl get storageclass

# 기본 StorageClass 확인
kubectl get sc -o wide

# StorageClass 상세
kubectl describe sc fast-ssd

# 바인딩 안 되는 PVC 확인
kubectl describe pvc pending-pvc
# Events 섹션에서 원인 확인

# PV 용량 확인
kubectl get pv --sort-by=.spec.capacity.storage

# 특정 StorageClass의 PV만 조회
kubectl get pv -l storageclass=fast-ssd

# 볼륨 마운트 확인
kubectl exec -it pod-name -- df -h
kubectl exec -it pod-name -- mount | grep /data