一、nfs-client-provisioner简介

nfs-client-provisioner 可动态为kubernetes提供pv卷，是Kubernetes的简易NFS的外部provisioner，本身不提供NFS，需要现有的NFS服务器提供存储。持久卷目录的命名规则为:${namespace}-${pvcName}-${pvName}。

K8S的外部NFS驱动可以按照其工作方式（是作为NFS server还是NFS client）分为两类：

nfs-client:

它通过K8S内置的NFS驱动挂载远端的NFS服务器到本地目录；然后将自身作为storage provider关联storage class。当用户创建对应的PVC来申请PV时，该provider就将PVC的要求与自身的属性比较，一旦满足就在本地挂载好的NFS目录中创建PV所属的子目录，为Pod提供动态的存储服务。

nfs-server:

与nfs-client不同，该驱动并不使用k8s的NFS驱动来挂载远端的NFS到本地再分配，而是直接将本地文件映射到容器内部，然后在容器内使用ganesha.nfsd来对外提供NFS服务；在每次创建PV的时候，直接在本地的NFS根目录中创建对应文件夹，并export出该子目录。

本文将介绍使用nfs-client-provisioner这个应用，利用NFS Server给Kubernetes作为持久存储的后端，并且动态提供PV。前提条件是有已经安装好的NFS服务器，并且NFS服务器与Kubernetes的Slave节点网络能够连通。将nfs-client驱动做为一个deployment部署到K8S集群中，然后对外提供存储服务

二、准备NFS服务端

2.0 当前环境信息

[root@k8s-master]-[~/nfs-provisioner]-#kubectl get node -o wide
NAME         STATUS   ROLES           AGE     VERSION   INTERNAL-IP   EXTERNAL-IP   OS-IMAGE                KERNEL-VERSION                CONTAINER-RUNTIME
k8s-master   Ready    control-plane   4d19h   v1.24.0   10.0.0.16     <none>        CentOS Linux 7 (Core)   3.10.0-1160.45.1.el7.x86_64   containerd://1.6.2
k8s-node-1   Ready    <none>          4d19h   v1.24.0   10.0.0.17     <none>        CentOS Linux 7 (Core)   3.10.0-1160.45.1.el7.x86_64   containerd://1.6.2
k8s-node-2   Ready    <none>          4d19h   v1.24.0   10.0.0.18     <none>        CentOS Linux 7 (Core)   3.10.0-1160.45.1.el7.x86_64   containerd://1.6.2

2.1 通过yum安装nfs server端

rpm -qa|egrep "nfs|rpc"
yum -y install nfs-utils rpcbind

2.2 启动服务和设置开机启动

#启动nfs-server，并加入开机启动
systemctl start rpcbind.service
systemctl enable rpcbind.service
systemctl start nfs
systemctl enable nfs-server --now
 
#查看nfs server是否已经正常启动
systemctl status nfs-server

 2.3  编辑配置文件，设置共享目录

[root@k8s-node-2]-[/data/nfs_provisioner]-#vim /etc/exports
/data/nfs_provisioner   10.0.0.0/24(rw,no_root_squash)
 
 #不用重启nfs服务,配置文件就会生效
exportfs -arv 

用于配置NFS服务程序配置文件的参数：

2.4 客户端尝试挂载

2.4.1 客户端需要安装nfs-utils，否则将无法进行nfs的挂载

yum -y install nfs-utils
systemctl start nfs
systemctl enable nfs
systemctl status nfs

2.4.2 nfs-server创建共享目录

mkdir /nfs_data

2.4.3 客户端测试

#查看nfs-server共享的目录
[root@k8s-master]-[~]-#showmount -e 10.0.0.18
Export list for 10.0.0.18:
/data/nfs_provisioner 10.0.0.0/24
 
#本地创建一个目录作为挂载点
mount  -t nfs 10.0.0.18:/data/nfs_provisioner /nfs_data
#将nfs-server的共享目录挂载到本地
 
#通过df -Th
[root@k8s-node-1]-[~]-#df -Th /nfs_data/
Filesystem              Type  Size  Used Avail Use% Mounted on
/dev/mapper/centos-root xfs    39G  7.9G   31G  21% /

三、部署nfs-provisioner

3.1 创建ServiceAccount

apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: default
---
kind: ClusterRole
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: nfs-client-provisioner-runner
rules:
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["get", "list", "watch"]
  - 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: ["create", "update", "patch"]
---
kind: ClusterRoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: run-nfs-client-provisioner
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    # replace with namespace where provisioner is deployed
    namespace: default
roleRef:
  kind: ClusterRole
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: default
rules:
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["get", "list", "watch", "create", "update", "patch"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: leader-locking-nfs-client-provisioner
  # replace with namespace where provisioner is deployed
  namespace: default
subjects:
  - kind: ServiceAccount
    name: nfs-client-provisioner
    # replace with namespace where provisioner is deployed
    namespace: default
roleRef:
  kind: Role
  name: leader-locking-nfs-client-provisioner
  apiGroup: rbac.authorization.k8s.io

kubectl apply -f sa.yaml

 3.2 创建Deployment

注意镜像需要用比较新的，不然会报错：unexpected error getting claim reference: selfLink was empty, can't make reference

注意：千万不要使用以下方式来解决selfLink的问题，k8s1.24.0版本默认是true,不支持修改为false,否则apiserver会启动失败！

kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-client-provisioner
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nfs-client-provisioner
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: nfs-client-provisioner
    spec:
      serviceAccountName: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: registry.cn-beijing.aliyuncs.com/mydlq/nfs-subdir-external-provisioner:v4.0.0
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: nfs-provisioner # 和3.Storage中provisioner保持一致便可
            - name: NFS_SERVER
              value: 10.0.0.18
            - name: NFS_PATH
              value: /data/nfs_provisioner
      volumes:
        - name: nfs-client-root
          nfs:
            server: 10.0.0.18
            path: /data/nfs_provisioner

kubectl apply -f deployment.yaml

 3.3 创建storageclass

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
  name: nfs-storage
provisioner: nfs-provisioner
volumeBindingMode: Immediate
reclaimPolicy: Delete

kubectl apply -f sc.yaml

 四、创建应用测试动态添加PV

4.1 创建一个nginx应用

kubectl apply -f nginx_sts_pvc.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: nginx
        ports:
        - containerPort: 80
          name: web
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      storageClassName: "nfs-storage"  #使用新建的sc
      resources:
        requests:
          storage: 10Mi

4.2 检查结果

检查nfs-server服务器是否创建pv持久卷：

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