PersistentVolume（PV） 資料持久卷
對存盤資源的創建與使用進行抽象，讓存盤可以做為集群的資源進行管理
PersistentVolumeClaim(PVC) 資料持久卷請求
讓用戶不需要關心具體的volume實作細節
靜態PV的實作：
Kubernetes支持持久卷的存盤插件： https://kubernetes.io/docs/concepts/storage/persistent-volumes/
首先配置PV：
1 #在/ifs/kubernetes/目錄下創建pv01,pv02,pv03 2 [root@node2 ~]# cd /ifs/kubernetes/ 3 [root@node2 kubernetes]# mkdir pv01 4 [root@node2 kubernetes]# mkdir pv02 5 [root@node2 kubernetes]# mkdir pv03 6 7 #通過pv.yaml檔案創建三個PV 8 #訪問模式： 9 #ReadWriteMany RWX 所有pod讀寫，應用場景：資料獨立，塊設備 10 #ReadWriteOnce RWO 單個Pod讀寫 11 #ReadOnlyMany ROX 所有pod只讀 應用場景：資料共享，檔案系統 12 [root@master ~]# cat pv.yaml 13 apiVersion: v1 14 kind: PersistentVolume 15 metadata: 16 name: pv01 #PV的名字 17 spec: 18 capacity: #定義容量為5G 19 storage: 5Gi 20 accessModes: #訪問模式為ReadWriteMany 21 - ReadWriteMany 22 nfs: #卷的型別為nfs 23 path: /ifs/kubernetes/pv01 #路徑為/ifs/kubernetes/pv01 24 server: 192.168.1.63 #nfs的服務器為：192.168.1.63 25 --- 26 apiVersion: v1 27 kind: PersistentVolume 28 metadata: 29 name: pv02 30 spec: 31 capacity: 32 storage: 10Gi 33 accessModes: 34 - ReadWriteMany 35 nfs: 36 path: /ifs/kubernetes/pv02 37 server: 192.168.1.63 38 --- 39 apiVersion: v1 40 kind: PersistentVolume 41 metadata: 42 name: pv03 43 spec: 44 capacity: 45 storage: 20Gi 46 accessModes: 47 - ReadWriteMany 48 nfs: 49 path: /ifs/kubernetes/pv03 50 server: 192.168.1.63 51 52 [root@master ~]# 53 [root@master ~]# kubectl apply -f pv.yaml 54 persistentvolume/pv01 created 55 persistentvolume/pv02 created 56 persistentvolume/pv03 created 57 [root@master ~]# kubectl get pv 58 NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE 59 pv01 5Gi RWX Retain Available 11s 60 pv02 10Gi RWX Retain Available 11s 61 pv03 20Gi RWX Retain Available 11s 62 [root@master ~]#
以deployment的方式使用靜態PVC
1 [root@master ~]# #通過deployment控制器啟動一個Pod,在這個Pod中資料 2 #持久化通過PVC來實作 3 #deployment和PVC通過name:my-pvc進行關聯 4 #兩個yaml檔案通常是寫在一起的 5 [root@master ~]# cat deployment2.yaml 6 apiVersion: apps/v1 7 kind: Deployment 8 metadata: 9 labels: 10 app: web 11 name: web 12 spec: 13 replicas: 1 14 selector: 15 matchLabels: 16 app: web 17 strategy: {} 18 template: 19 metadata: 20 labels: 21 app: web 22 spec: 23 containers: 24 - image: nginx 25 name: nginx 26 resources: {} 27 volumeMounts: 28 - name: data 29 mountPath: /usr/share/nginx/html 30 31 volumes: 32 - name: data 33 persistentVloumeClaim: 34 claimName: my-pvc 35 --- 36 apiVersion: v1 37 38 kind: PersistentVolumeClaim 39 metadata: 40 name: my-pvc 41 spec: 42 accessModes: 43 - ReadWriteMany 44 resources: 45 requests: 46 storage: 8Gi 47 [root@master ~]# 48 49 [root@master ~]# kubectl apply -f deployment2.yaml 50 deployment.apps/web created 51 persistentvolumeclaim/my-pvc created 52 [root@master ~]# kubectl get pod 53 NAME READY STATUS RESTARTS AGE 54 web-7d74df4646-fr88j 1/1 Running 0 15s 55 [root@master ~]# kubectl get pvc 56 NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE 57 my-pvc Bound pv02 10Gi RWX 27s 58 [root@master ~]#
PVC與PV的關系
PV與PVC是一一對應的，名為my-pvc的PVC最終匹配的是PV02,一個PVC只可能匹配一個pv
PVC與PV之間的對應是由匹配條件決定的，PVC與PV的匹配條件是：
1 容量
2 訪問模式
3 標簽
1 [root@master ~]# kubectl get pv 2 NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE 3 pv01 5Gi RWX Retain Available 67s 4 pv02 10Gi RWX Retain Bound default/my-pvc 67s 5 pv03 20Gi RWX Retain Available 67s 6 [root@master ~]# #PVX洗掉了之后，對應的PV中的資料并不會洗掉 7 #如下圖中的pv02，my-pvc洗掉后，pv02中的資料還是存在的可以對 8 #pv02中的資料進行洗掉或者備份 9 #同時pv02已不可以再次使用，即它的狀態無法再回到available 10 #如果確定不再使用pv02中的資料，可以手動洗掉pv02 11 #pv洗掉之后對就的存盤是否洗掉是由RECLAIM POLICY決定的： 12 #RECLAIM POLICY的狀態有 13 #Delete: 直接洗掉PV+資料 （不推薦） 14 #Recycle: 清除資料，但保留PV（被廢棄） 15 #Retain: 保留PV&資料 （推薦） 16 17 [root@master ~]# kubectl delete -f deployment2.yaml 18 deployment.apps "web" deleted 19 persistentvolumeclaim "my-pvc" deleted 20 [root@master ~]# kubectl get pv,pvc 21 NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE 22 persistentvolume/pv01 5Gi RWX Retain Available 86m 23 persistentvolume/pv02 10Gi RWX Retain Released default/my-pvc 86m 24 persistentvolume/pv03 20Gi RWX Retain Available 86m 25 [root@master ~]# 26
動態PVC的實作：
靜態PVC的缺點：
PV需要提前手動創建，PVC在使用PV時可能會出現實作用的PV大于PVC請求的PV
動態PVC可以解決這個問題，當PVC需要PV時會自動創建PVC需求的PV
StorageClass用于自動創建PV, 并不是所有存盤型別都支持StorageClass的自動創建，
查看StorageClass支持的存盤串列：
https://kubernetes.io/docs/concepts/storage/storage-classes/
如果默認不支持的存盤型別仍需要使用動態PVC，那么可以使用的插件串列如下
https://github.com/kubernetes-retired/external-storage/
如下示例，以nfs的存盤型別配置動態PVC
StorageClass默認不是支持nfs型別的PVC的，所以需要手動安裝插件
1 [root@master NFS]# rz -E 2 rz waiting to receive. 3 [root@master NFS]# ls 4 nfs-client.zip 5 [root@master NFS]# unzip nfs-client.zip 6 [root@master NFS]# cd nfs-client/ 7 [root@master nfs-client]# ls 8 class.yaml deployment.yaml rbac.yaml 9 [root@master nfs-client]# #定義一下StorageClass資源 10 [root@master nfs-client]# cat class.yaml 11 apiVersion: storage.k8s.io/v1 12 kind: StorageClass 13 metadata: 14 name: managed-nfs-storage #storageclass資源的名字 15 provisioner: fuseim.pri/ifs # or choose another name, must match deployment's env PROVISIONER_NAME' 16 parameters: 17 archiveOnDelete: "true" 18 [root@master nfs-client]# #以容器的方式運行應用程式 19 [root@master nfs-client]# cat deployment.yaml 20 apiVersion: v1 21 kind: ServiceAccount 22 metadata: 23 name: nfs-client-provisioner 24 --- 25 kind: Deployment 26 apiVersion: apps/v1 27 metadata: 28 name: nfs-client-provisioner 29 spec: 30 replicas: 1 31 strategy: 32 type: Recreate 33 selector: 34 matchLabels: 35 app: nfs-client-provisioner 36 template: 37 metadata: 38 labels: 39 app: nfs-client-provisioner 40 spec: 41 serviceAccountName: nfs-client-provisioner 42 containers: 43 - name: nfs-client-provisioner 44 image: quay.io/external_storage/nfs-client-provisioner:latest 45 volumeMounts: 46 - name: nfs-client-root 47 mountPath: /persistentvolumes 48 env: 49 - name: PROVISIONER_NAME 50 value: fuseim.pri/ifs #這個變數要與class.yaml檔案中的一致 51 - name: NFS_SERVER 52 value: 192.168.1.63 #nfs服務器的地址 53 - name: NFS_PATH 54 value: /ifs/kubernetes 55 volumes: 56 - name: nfs-client-root 57 nfs: 58 server: 192.168.1.63 59 path: /ifs/kubernetes 60 [root@master nfs-client]# #rbac.yaml的作用是授權nfs-client-provisioner這個容器中的 61 #應用程式可以訪問K8S的API，從API中獲取是否有新的PVC創建 62 #并根據PVC的請求自動創建PV 63 [root@master nfs-client]# cat rbac.yaml 64 kind: ServiceAccount 65 apiVersion: v1 66 metadata: 67 name: nfs-client-provisioner 68 --- 69 kind: ClusterRole 70 apiVersion: rbac.authorization.k8s.io/v1 71 metadata: 72 name: nfs-client-provisioner-runner 73 rules: 74 - apiGroups: [""] 75 resources: ["persistentvolumes"] 76 verbs: ["get", "list", "watch", "create", "delete"] 77 - apiGroups: [""] 78 resources: ["persistentvolumeclaims"] 79 verbs: ["get", "list", "watch", "update"] 80 - apiGroups: ["storage.k8s.io"] 81 resources: ["storageclasses"] 82 verbs: ["get", "list", "watch"] 83 - apiGroups: [""] 84 resources: ["events"] 85 verbs: ["create", "update", "patch"] 86 --- 87 kind: ClusterRoleBinding 88 apiVersion: rbac.authorization.k8s.io/v1 89 metadata: 90 name: run-nfs-client-provisioner 91 subjects: 92 - kind: ServiceAccount 93 name: nfs-client-provisioner 94 namespace: default 95 roleRef: 96 kind: ClusterRole 97 name: nfs-client-provisioner-runner 98 apiGroup: rbac.authorization.k8s.io 99 --- 100 kind: Role 101 apiVersion: rbac.authorization.k8s.io/v1 102 metadata: 103 name: leader-locking-nfs-client-provisioner 104 rules: 105 - apiGroups: [""] 106 resources: ["endpoints"] 107 verbs: ["get", "list", "watch", "create", "update", "patch"] 108 --- 109 kind: RoleBinding 110 apiVersion: rbac.authorization.k8s.io/v1 111 metadata: 112 name: leader-locking-nfs-client-provisioner 113 subjects: 114 - kind: ServiceAccount 115 name: nfs-client-provisioner 116 # replace with namespace where provisioner is deployed 117 namespace: default 118 roleRef: 119 kind: Role 120 name: leader-locking-nfs-client-provisioner 121 apiGroup: rbac.authorization.k8s.io 122 [root@master nfs-client]# 123 [root@master nfs-client]# kubectl apply -f . 124 storageclass.storage.k8s.io/managed-nfs-storage created 125 serviceaccount/nfs-client-provisioner created 126 deployment.apps/nfs-client-provisioner created 127 serviceaccount/nfs-client-provisioner unchanged 128 clusterrole.rbac.authorization.k8s.io/nfs-client-provisioner-runner created 129 clusterrolebinding.rbac.authorization.k8s.io/run-nfs-client-provisioner created 130 role.rbac.authorization.k8s.io/leader-locking-nfs-client-provisioner created 131 rolebinding.rbac.authorization.k8s.io/leader-locking-nfs-client-provisioner created 132 [root@master nfs-client]# kubectl get pod 133 NAME READY STATUS RESTARTS AGE 134 nfs-client-provisioner-7676dc9cfc-j4vgl 1/1 Running 0 22s 135 [root@master nfs-client]#
如上圖示，PVC請求的存盤型別是官方默念支持的存盤型別，那么是不需要managed-nfs-storage ，
managed-nfs-storage 也正是deployment.yaml 檔案容器中的應用程式
1 [root@master nfs-client]# kubectl get sc 2 NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE 3 managed-nfs-storage fuseim.pri/ifs Delete Immediate false 53m 4 [root@master nfs-client]#
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