# 按顺序定义 sc，pvc，pod

# https://kubernetes.io/zh-cn/docs/concepts/storage/storage-classes/#local

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: sc-hostpath
provisioner: kubernetes.io/no-provisioner # 使用hostpath作为存储后端

# volumeBindingMode: WaitForFirstConsumer 表示等待Pod调度到节点后才会申领实际的卷空间；

# - 默认是Immediate，表示直接在创建PVC时直接使用后端存储空间

volumeBindingMode: WaitForFirstConsumer
allowVolumeExpansion: true # 允许PV扩容（不允许缩容）
reclaimPolicy: Delete # 默认Delete

---

# 注意：一个PV只能绑定一个PVC。也就是说，使用hostpath搭配StorageClass时，当这个PV被任何一个Pod占用时（生成一个PVC），则这个PV无法再被其他Pod占用

# - 所以在下面的 matchExpressions 处一般只会匹配一个节点；若要使用其他节点，则要再创建同storageClassName而不同名的PV资源

apiVersion: v1
kind: PersistentVolume
metadata:
  name: sc-pv-hostpath
spec:
  capacity:
    storage: 500Gi # 创建时并不会验证实际有这么多空间
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain # 手动创建本地卷时，仅支持Retain
  storageClassName: sc-hostpath # 匹配上面的metadata.name
  local:
    path: /home/host-sc-pv-dir # 必须在节点手动创建
  nodeAffinity: # 创建本地卷的必须字段，k8s会在匹配下面条件的节点上创建PV，如果没有匹配的节点，则引用的Pod和PV都会一直pending（通过describe可以查看原因）
    required:
      nodeSelectorTerms:
        - matchExpressions:
            - key: kubernetes.io/hostname
              operator: In
              values:

                - k8s-node1
---

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: sc-pvc-hostpath
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: sc-hostpath
  resources:
    requests:
      storage: 500Gi

---

apiVersion: v1
kind: Pod
metadata:
  name: busybox-use-sc-pvc
  labels:
    app: busybox
spec:
  containers:
    - name: write
      image: busybox
      command: [ "sh", "-c" ]
      args: [ "echo 'hellok8s, pvc used!' > /write_dir/data; sleep infinity" ]
      volumeMounts:
        - mountPath: /write_dir
          name: pvc-dir
  volumes:
    - name: pvc-dir
      persistentVolumeClaim:
        claimName: sc-pvc-hostpath