1、Kubernetes集群管理員通過提供不同的存儲類，可以滿足用戶不同的服務質量級別、備份策略和任意策略要求的存儲需求。動態存儲卷供應使用StorageClass進行實現，其允許存儲卷按需被創建。如果沒有動態存儲供應，Kubernetes集群的管理員將不得不通過手工的方式類創建新的存儲卷。通過動態存儲卷，Kubernetes將能夠按照用戶的需要，自動創建其需要的存儲。

 

基於StorageClass的動態存儲供應整體過程如下圖所示：

1）集群管理員預先創建存儲類（StorageClass）；

2）用戶創建使用存儲類的持久化存儲聲明(PVC：PersistentVolumeClaim)；

3）存儲持久化聲明通知系統，它需要一個持久化存儲(PV: PersistentVolume)；

4）系統讀取存儲類的信息；

5）系統基於存儲類的信息，在后台自動創建PVC需要的PV；

6）用戶創建一個使用PVC的Pod；

7）Pod中的應用通過PVC進行數據的持久化；

8）而PVC使用PV進行數據的最終持久化處理。

 

2、example

首先創建nfs服務，參考另外一篇文章：http://www.cnblogs.com/cuishuai/p/7798154.html

1）創建rbac授權，（如果集群開啟了rbac）

# cat nfs-rbac.yaml

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-provisioner
  namespace: monitoring
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
   name: nfs-provisioner-runner
   namespace: monitoring
rules:
   -  apiGroups: [""]
      resources: ["persistentvolumes"]
      verbs: ["get", "list", "watch", "create", "delete"]
   -  apiGroups: [""]
      resources: ["persistentvolumeclaims"]
      verbs: ["get", "list", "watch", "update"]
   -  apiGroups: ["storage.k8s.io"]
      resources: ["storageclasses"]
      verbs: ["get", "list", "watch"]
   -  apiGroups: [""]
      resources: ["events"]
      verbs: ["watch", "create", "update", "patch"]
   -  apiGroups: [""]
      resources: ["services", "endpoints"]
      verbs: ["get","create","list", "watch","update"]
   -  apiGroups: ["extensions"]
      resources: ["podsecuritypolicies"]
      resourceNames: ["nfs-provisioner"]
      verbs: ["use"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-nfs-provisioner
subjects:
  - kind: ServiceAccount
    name: nfs-provisioner
    namespace: monitoring
roleRef:
  kind: ClusterRole
  name: nfs-provisioner-runner
  apiGroup: rbac.authorization.k8s.io

 

 

2)創建nfs的nfs-client-provisioner

# cat nfs-deployment.yaml

 

kind: Deployment
apiVersion: extensions/v1beta1
metadata:
   name: nfs-client-provisioner
   namespace: monitoring
spec:
   replicas: 1
   strategy:
     type: Recreate
   template:
      metadata:
         labels:
            app: nfs-client-provisioner
      spec:
         serviceAccount: nfs-provisioner
         containers:
            -  name: nfs-client-provisioner
               image: quay.io/external_storage/nfs-client-provisioner:latest
               volumeMounts:
                 -  name: nfs-client-root
                    mountPath:  /persistentvolumes
               env:
                 -  name: PROVISIONER_NAME
                    value: fuseim.pri/ifs
                 -  name: NFS_SERVER
                    value: 10.2.68.77
                 -  name: NFS_PATH
                    value: /data/opv
         volumes:
           - name: nfs-client-root
             nfs:
               server: 10.2.68.77
               path: /data/opv

 

！！PS：10.2.68.77是nfs服務的監聽地址，/data/opv是nfs共享的目錄。

3)創建storageclass

# cat storageclass-nfs.yaml

 

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: grafana-nfs
  namespace: monitoring
provisioner: fuseim.pri/ifs
reclaimPolicy: Retain

 

reclaimPolicy：有兩種策略：Delete、Retain。默認是Delet 

！！PS：fuseim.pri/ifs為上面deployment上創建的PROVISIONER_NAME。

4)創建PersistenetVolumeClaim

在存儲類被正確創建后，就可以創建PersistenetVolumeClaim來請求StorageClass，而StorageClass將會為PersistenetVolumeClaim自動創建一個可用PersistentVolume。PersistenetVolumeClaim是對PersistenetVolume的聲明，即PersistenetVolume為存儲的提供者，而PersistenetVolumeClaim為存儲的消費者。

# cat pvc.yaml

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: test-claim
  namespace: monitoring
 # annotations:
 #   volume.beta.kubernetes.io/storage-class: "grafana-nfs"
spec:
  storageClassName: grafana-nfs
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Mi

 

！！PS：grafana-nfs為上面創建的storageclass的name，1Mi是設置的目錄的大小。

5)testpod

kind: Pod
apiVersion: v1
metadata:
  name: test-pod
  namespace: monitoring
spec:
  containers:
  - name: test-pod
    image: busybox
    command:
      - "/bin/sh"
    args:
      - "-c"
      - "touch /mnt/SUCCESS && exit 0 || exit 1"
    volumeMounts:
      - name: nfs-pvc
        mountPath: "/mnt"
  restartPolicy: "Never"
  volumes:
    - name: nfs-pvc
      persistentVolumeClaim:
        claimName: test-claim