CKAD 复习：存储题压缩模板

存储题记 4 个层次：emptyDir 是 Pod 内共享临时目录，PV 是集群里的真实存储，PVC 是命名空间里的申请单，Pod volumes 把 PVC 挂进去。

1. emptyDir：多容器共享临时目录

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apiVersion: v1
kind: Pod
metadata:
  name: shared-volume-pod
  namespace: storage-test
spec:
  containers:
  - name: writer
    image: busybox
    command: ["sh", "-c", "while true; do date >> /data/app.log; sleep 5; done"]
    volumeMounts:
    - name: data
      mountPath: /data
  - name: reader
    image: busybox
    command: ["sh", "-c", "tail -f /data/app.log"]
    volumeMounts:
    - name: data
      mountPath: /data
  volumes:
  - name: data
    emptyDir: {}

2. PV：集群级真实存储

hostPath 类型 PV 常用于模拟题。

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apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-storage
spec:
  capacity:
    storage: 1Gi
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: fast-storage
  hostPath:
    path: /mnt/data

3. StorageClass：动态或延迟绑定策略

无动态 provisioner 的本地模拟题常用 kubernetes.io/no-provisioner。

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apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-storage
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

4. PVC：命名空间里的申请单

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apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-app
  namespace: storage-test
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: fast-storage
  resources:
    requests:
      storage: 500Mi

检查绑定：

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k get pv
k get pvc -n storage-test
k describe pvc pvc-app -n storage-test

5. Pod 挂载 PVC

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apiVersion: v1
kind: Pod
metadata:
  name: pvc-pod
  namespace: storage-test
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "echo hello > /data/hello.txt && sleep 3600"]
    volumeMounts:
    - name: app-data
      mountPath: /data
  volumes:
  - name: app-data
    persistentVolumeClaim:
      claimName: pvc-app

6. StatefulApp 题的最小思路

如果题目要 StatefulSet，先抓 3 个关键字段：serviceName、volumeClaimTemplates、稳定副本名。

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apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
  namespace: state
spec:
  serviceName: web
  replicas: 2
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - name: nginx
        image: nginx
        volumeMounts:
        - name: data
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 500Mi

考场压缩记忆

emptyDir：Pod 生命周期内临时共享。
PV：集群级，写容量、访问模式、回收策略、后端类型。
PVC：命名空间级，写申请容量、访问模式、StorageClass。
Pod：通过 volumes.persistentVolumeClaim.claimName 使用 PVC。
绑定失败优先查 storageClassName、容量、accessModes。