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: 1GiaccessModes:        #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: /nfsdataserver: 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- ReadWriteOnceresources: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-nginxlabels:app: nginx
spec:containers:- name: mypod1image: daocloud.io/library/nginxports:- containerPort: 80volumeMounts:- mountPath: "/usr/share/nginx/html"name: mydatavolumes:- name: mydatapersistentVolumeClaim: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: 1GiaccessModes:- ReadWriteOncepersistentVolumeReclaimPolicy: RetainstorageClassName: nfsnfs: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:- ReadWriteOnceresources:requests:storage: 1GistorageClassName: 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: 3306targetPort: 3306selector:app: mysql
---
apiVersion: apps/v1
kind: Deployment
metadata:name: mysql
spec:selector:matchLabels:app: mysqltemplate:metadata:labels:app: mysqlspec:containers:- image: daocloud.io/library/mysql:5.7.5-m15name: mysqlenv:- name: MYSQL_ROOT_PASSWORDvalue: qinxue@123ports:- containerPort: 3306name: mysqlvolumeMounts:- name: mysql-persistent-storagemountPath: /var/lib/mysqlvolumes:- name: mysql-persistent-storagepersistentVolumeClaim: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: ServiceAccountname: nfs-client-provisionernamespace: default
roleRef:kind: ClusterRolename: nfs-client-provisioner-runnerapiGroup: 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-provisionerreplicas: 1strategy:type: Recreatetemplate:metadata:labels:app: nfs-client-provisionerspec:nodeName: k8s-node2serviceAccount: nfs-client-provisionercontainers:- name: nfs-client-provisionerimage: quay.io/external_storage/nfs-client-provisioner:latestvolumeMounts:- name: nfs-client-rootmountPath: /persistentvolumesenv:- name: PROVISIONER_NAMEvalue: fuseim.pri/ifs- name: NFS_SERVERvalue: 192.168.22.139- name: NFS_PATHvalue: /opt/container_datavolumes:- name: nfs-client-rootnfs:server: 192.168.22.139path: /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: nginxlabels:app: nginx
spec:ports:- port: 80name: webclusterIP: Noneselector:app: nginx
---
apiVersion: apps/v1
kind: StatefulSet
metadata:name: web
spec:serviceName: "nginx"replicas: 2selector:matchLabels:app: nginxtemplate:metadata:labels:app: nginxspec:containers:- name: nginximage: daocloud.io/library/nginx:1.13.0-alpineports:- containerPort: 80name: webvolumeMounts:- name: wwwmountPath: /usr/share/nginx/htmlvolumeClaimTemplates:- metadata:name: wwwspec: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；