k8s持久化存储PV和PVC

一、PV和PVC

1.PersistentVolume (PV)

PersistentVolume (PV) 是外部存储系统中的⼀块存储空间，由管理员创建和维护。与 Volume⼀样， PV 具有持久性，⽣命周期独⽴于 Pod；

2.PersistentVolumeClaim (PVC)

PersistentVolumeClaim (PVC) 是对 PV 的申请 (Claim) 。 PVC 通常由普通⽤户创建和维护。需要为 Pod 分配存储资源时，⽤户可以创建⼀个 PVC ，指明存储资源的容量⼤⼩和访问模式（⽐如只读）等信息，Kubernetes 会查找并提供满⾜条件的 PV；

二、通过NFS实现持久化存储

1.配置nfs

nfs--server	nfs-client
k8s-master	k8s-node1、k8s-node2

1）安装nfs服务——所有节点

[root@k8s-master ~] # yum install -y nfs-common nfs-utils

2）创建共享目录并授权——在nfs-server操作

[root@k8s-master ~]# mkdir /nfsdata

[root@k8s-master ~]# chmod 666 /nfsdata

3）编辑exports文件——在nfs-server操作

[root@k8s-master ~] # vim /etc/exports

[root@k8s-master ~] # cat /etc/exports

/nfsdata *(rw,no_root_squash,no_all_squash,sync)

4）启动rpc和nfs——在nfs-server操作

[root@k8s-master ~] # systemctl start rpcbind

[root@k8s-master ~] # systemctl start nfs

5）测试NFS挂载是否可用

在nfs-client操作

[root@k8s-node2 ~] # mkdir /test

[root@k8s-node2 ~] # mount -t nfs 192.168.22.139:/nfsdata /test/ #nfs-server的IP

[root@k8s-node2 ~] # df -Th|grep "/test"

192.168.22.139: /nfsdata nfs4 19G 9 .9G 9 .0G 53 % /test

[root@k8s-node2 ~] # touch /test/ip.txt

[root@k8s-node2 ~] # ls /test/

ip.txt

在nfs-server操作

[root@k8s-master ~] # ls /nfsdata/

ip.txt

[root@k8s-node2 ~] # umount /test #测试完成之后，就可以卸载了

2.创建PV

1）编写yaml配置文件

[root@k8s-master ~]# vim nfs-pv1.yaml 
[root@k8s-master ~]# cat nfs-pv1.yaml 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mypv1
spec:
  capacity:            #指定PV的容量
    storage: 1Gi
  accessModes:        #指定访问模式
    - ReadWriteOnce        #指PV能以read-write模式mount到单个节点
  persistentVolumeReclaimPolicy: Recycle       #指定当前PV的回收策略为Recycle，清除PV中的数据
  storageClassName: nfs        #指定PV的class为nfs；相当于为PV设置了一个分类
  nfs:
    path: /nfsdata
    server: 192.168.22.139      #指定nfs目录所在的机器的地址

PS：

1）accessModes 指定访问模式为 ReadWriteOnce ，⽀持的访问模式有：

ReadWriteOnce – PV 能以 read-write 模式 mount 到单个节点。

ReadOnlyMany – PV 能以 read-only 模式 mount 到多个节点。

ReadWriteMany – PV 能以 read-write 模式 mount 到多个节点

2）persistentVolumeReclaimPolicy 指定当前 PV 的回收策略，⽀持的策略有：

Retain – 需要管理员⼿⼯回收。

Recycle – 清除 PV 中的数据，效果相当于执⾏ rm -rf /nfsdata/* 。

Delete – 删除 Storage Provider 上的对应存储资源，例如 AWS EBS、GCE PD、Azure Disk、OpenStack Cinder Volume 等

2）应用并创建mypv1

[root@k8s-master ~]# kubectl apply -f nfs-pv1.yaml 
persistentvolume/mypv1 created
[root@k8s-master ~]# kubectl get pv
NAME    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
mypv1   1Gi        RWO            Recycle          Available           nfs                     8s
# STATUS为Available，表示mypv1准备就绪，可以被PVC申请

3.创建PVC

1）编写yaml文件

[root@k8s-master ~]# vim nfs-pvc1.yaml 
[root@k8s-master ~]# cat nfs-pvc1.yaml 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mypvc1
spec:
  accessModes:        #指定访问模式
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi        #指定访问PV的容量
  storageClassName: nfs        #指定访问PV的class

2）应用并查看

[root@k8s-master ~]# kubectl apply -f nfs-pvc1.yaml 
persistentvolumeclaim/mypvc1 created
[root@k8s-master ~]# kubectl get pvc
NAME     STATUS   VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mypvc1   Bound    mypv1    1Gi        RWO            nfs            6s
[root@k8s-master ~]# kubectl get pv
NAME    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM            STORAGECLASS   REASON   AGE
mypv1   1Gi        RWO            Recycle          Bound    default/mypvc1   nfs                     12m

#从查询pv和pvc的结果来看，mypvc1已经Bound到mypv1，申请成功

4.创建pod

1）编写pod的yaml文件并应用

[root@k8s-master ~]# vim pod1.yaml
[root@k8s-master ~]# cat pod1.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: nfs-pod-nginx
  labels:
    app: nginx
spec:
  containers:
    - name: mypod1
      image: daocloud.io/library/nginx
      ports:
      - containerPort: 80
      volumeMounts:
      - mountPath: "/usr/share/nginx/html"
        name: mydata
  volumes:
    - name: mydata
      persistentVolumeClaim:
        claimName: mypvc1
[root@k8s-master ~]# kubectl apply -f pod1.yaml 
pod/nfs-pod-nginx created

5.验证

[root@k8s-master ~]# kubectl exec -it nfs-pod-nginx /bin/bash
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@nfs-pod-nginx:/# ls /usr/share/nginx/html/
ip.txt        #上述/nfsdata中的文件
root@nfs-pod-nginx:/# echo "hello!" > /usr/share/nginx/html/index.html
root@nfs-pod-nginx:/# exit
exit
command terminated with exit code 130
[root@k8s-master ~]# ls /nfsdata/    #也可在nfs的共享⽬录中查看到，说明卷共享成功
index.html  ip.txt
[root@k8s-master ~]# cat /nfsdata/index.html 
hello!

三、PV的回收

1.Retain回收策略

2.删除pod、pvc、pv

[root@k8s-master ~]# kubectl delete pod nfs-pod-nginx
pod "nfs-pod-nginx" deleted
[root@k8s-master ~]# kubectl delete pvc mypvc1
persistentvolumeclaim "mypvc1" deleted
[root@k8s-master ~]# kubectl get pv
NAME    CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM            STORAGECLASS   REASON   AGE
mypv1   1Gi        RWO            Retain          Released   default/mypvc1   nfs                     98m
# 虽然 mypv1 中的数据得到了保留，但其 PV 状态会⼀直处于 Released ，不能被其他PVC申请；
# 为了重新使⽤存储资源，可以删除并重新创建mypv1；删除操作只是删除了PV对象，存储空间中的数据并不会被删除
[root@k8s-master ~]# kubectl delete pv mypv1
persistentvolume "mypv1" deleted
[root@k8s-master ~]# ls /nfsdata/index.html 
/nfsdata/index.html
[root@k8s-master ~]# cat /nfsdata/index.html 
hello!

四、PV&PVC应用在MySQL的持久化存储

1.创建pv和pvc

1）创建pv，mysql-pv.yaml文件

[root@k8s-master mysqlpv]# vim mysql-pv.yaml
[root@k8s-master mysqlpv]# cat mysql-pv.yaml 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: nfs
  nfs:
    path: /nfsdata/mysql-pv    #记得创建这个目录
    server: 192.168.22.139
[root@k8s-master mysqlpv]# kubectl apply -f mysql-pv.yaml 
persistentvolume/mysql-pv created

2）创建PVC，mysql-pvc.yaml文件

[root@k8s-master mysqlpv]# vim mysql-pvc.yaml 
[root@k8s-master mysqlpv]# cat mysql-pvc.yaml 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: nfs
[root@k8s-master mysqlpv]# kubectl apply -f mysql-pvc.yaml 
persistentvolumeclaim/mysql-pvc created

2.部署MySQL

编写mysql-pod.yaml文件

[root@k8s-master mysqlpv]# vim mysql-pod.yaml
[root@k8s-master mysqlpv]# cat mysql-pod.yaml 
apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
  - port: 3306
    targetPort: 3306
  selector:
    app: mysql
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - image: daocloud.io/library/mysql:5.7.5-m15
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: qinxue@123
        ports:
        - containerPort: 3306
          name: mysql
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: mysql-pvc
[root@k8s-master mysqlpv]# kubectl apply -f mysql-pod.yaml 
service/mysql created
deployment.apps/mysql created

3.向MySQL添加数据

1）查看MySQL部署在node2节点

[root@k8s-master mysqlpv]# kubectl get pod -o wide | grep mysql
mysql                   1/1     Running   6 (3h27m ago)   13d   10.244.1.45   k8s-node1   <none>           <none>
mysql-55c4f546d-4nkt9   1/1     Running   0               43s   10.244.2.52   k8s-node2   <none>           <none>

2）进入容器并登录mysql

[root@k8s-master mysqlpv]# kubectl exec -it mysql-bd87b4f8f-l6tdx /bin/bash
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.
root@mysql-bd87b4f8f-l6tdx:/# mysql -uroot -p‘qinxue@123’

3）添加数据

mysql> create database db1
Query OK, 1 row affected (0.00 sec)

4.验证数据一致性

1）删除deployment，pvc，pv；然后重新创建pv，pvc，deployment；数据在Mysql中，仍然挂载成功；

五、PV/PVC动态供应项目实战

Dynamic Provisioning机制⼯作的核⼼在于StorageClass的API对象。

StorageClass声明存储插件，⽤于⾃动创建PV

Kubernetes⽀持动态供给的存储插件：

https://kubernetes.io/docs/concepts/storage/storage-classes/

因为NFS不⽀持动态存储，所以我们需要借⽤这个存储插件。

nfs动态相关部署可以参考：

https://github.com/kubernetes-incubator/external-storage/tree/master/nfs-client/deploy

1.定义一个storage

[root@k8s-master pv-pvc]# vim storageclass-nfs.yaml
[root@k8s-master pv-pvc]# cat storageclass-nfs.yaml 
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: managed-nfs-storage
provisioner: fuseim.pri/ifs
[root@k8s-master pv-pvc]# kubectl apply -f storageclass-nfs.yaml 
storageclass.storage.k8s.io/managed-nfs-storage created
[root@k8s-master pv-pvc]# kubectl get sc
NAME                  PROVISIONER      RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
managed-nfs-storage   fuseim.pri/ifs   Delete          Immediate           false                  20s

2.部署授权

1）因为storage⾃动创建pv需要经过kube-apiserver,所以要进⾏授权

2）创建1个serviceaccount；创建1个clusterrole，并赋予应该具有的权限，⽐如对于⼀些基本api资源的增删改查；创建1个clusterrolebinding，将sa和clusterrole绑定到⼀起；这样sa就有权限了；然后pod中再使⽤这个sa，那么pod再创建的时候，会⽤到sa，sa具有创建pv的权限，便可以⾃动创建pv；

[root@k8s-master pv-pvc]# vim rabc.yaml
[root@k8s-master pv-pvc]# cat rabc.yaml 
apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: nfs-client-provisioner-runner
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: ["list", "watch", "create", "update", "patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-nfs-client-provisioner
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    namespace: default
roleRef:
  kind: ClusterRole
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io
[root@k8s-master pv-pvc]# kubectl apply -f rabc.yaml 
serviceaccount/nfs-client-provisioner created
clusterrole.rbac.authorization.k8s.io/nfs-client-provisioner-runner created
clusterrolebinding.rbac.authorization.k8s.io/run-nfs-client-provisioner created
[root@k8s-master pv-pvc]# kubectl get sa
NAME                     SECRETS   AGE
default                  0         14d
nfs-client-provisioner   0         14s
[root@k8s-master pv-pvc]# kubectl get cr |grep nfs
error: the server doesn't have a resource type "cr"
[root@k8s-master pv-pvc]# kubectl get clusterrole |grep nfs
nfs-client-provisioner-runner                                          2024-08-06T04:52:23Z
[root@k8s-master pv-pvc]# kubectl get clusterrolebinding |grep nfs
run-nfs-client-provisioner                             ClusterRole/nfs-client-provisioner-runner                                          3m58s

3.部署一个自动创建pv的pod服务

这⾥⾃动创建pv的服务由nfs-client-provisioner 完成

[root@k8s-master pv-pvc]# vim deployment-nfs.yaml
[root@k8s-master pv-pvc]# cat deployment-nfs.yaml 
kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-client-provisioner
spec:
  selector:
    matchLabels:
      app: nfs-client-provisioner
  replicas: 1
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: nfs-client-provisioner
    spec:
      nodeName: k8s-node2
      serviceAccount: nfs-client-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: 192.168.22.139
            - name: NFS_PATH
              value: /opt/container_data
      volumes:
        - name: nfs-client-root
          nfs:
            server: 192.168.22.139
            path: /opt/container_data
[root@k8s-master pv-pvc]# kubectl apply -f deployment-nfs.yaml 
deployment.apps/nfs-client-provisioner created
# nfs-client-provisioner 会以pod运⾏在k8s中
[root@k8s-master pv-pvc]# kubectl get pod |grep nfs
nfs-client-provisioner-6c745f9d9-msrtp   1/1     Running   0             6s

4.部署有状态服务，测试自动创建pv

部署yaml⽂件参考：https://kubernetes.io/docs/tutorials/stateful-application/basic-stateful-set/

这里部署nginx服务

[root@k8s-master pv-pvc]# cat nginx.yaml 
apiVersion: v1
kind: Service
metadata:
  name: nginx
  labels:
    app: nginx
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  serviceName: "nginx"
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: daocloud.io/library/nginx:1.13.0-alpine
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "managed-nfs-storage"
      resources:
        requests:
          storage: 1Gi
[root@k8s-master pv-pvc]# kubectl apply -f nginx.yaml 
service/nginx created
statefulset.apps/web created
[root@k8s-master pv-pvc]# kubectl get pod
NAME                                     READY   STATUS    RESTARTS      AGE
configmap-pod                            1/1     Running   5 (52m ago)   12d
configmap-test-pod                       1/1     Running   5 (52m ago)   12d
mypod                                    1/1     Running   7 (52m ago)   13d
mysql                                    1/1     Running   7 (52m ago)   13d
nfs-client-provisioner-6c745f9d9-msrtp   1/1     Running   0             19m
tomcat                                   1/1     Running   7 (52m ago)   14d
web-0                                    1/1     Running   0             42s
web-1                                    1/1     Running   0             16s
# web-0创建成功后才会创建web-1

2）进入容器内在/usr/share/nginx/html目录下创建文件验证；删除一个pod后，数据仍然存在，不会丢失；