步步深入 k8s 使用 pv pvc sc 在 nfs 基础上共享存储

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前言

持久化卷（Persistent Volume, PV）允许用户将外部存储映射到集群，而持久化卷申请（Persistent Volume Claim, PVC）则类似于许可证，使有授权的应用（Pod）可以使用PV。

持久化卷（Persistent Volume，PV）。
持久化卷申请（Persistent Volume Claim，PVC）。
存储类（Storage Class，SC）。

概括地说，PV代表的是Kubernetes中的存储；PVC就像许可证，赋予Pod访问PV的权限；sc则使分配过程是动态的。

集群环境

操作系统: Ubuntu 20.04

IP	Hostname	配置
192.168.254.130	master01	2C 4G 30G
192.168.254.131	node01	2C 4G 30G
192.168.254.132	node02	2C 4G 30G
192.168.254.133	nfs-tools	2C 4G 30G

nfs 环境搭建

安装 nfs

sudo apt-get install -y nfs-kernel-server  # 安装 NFS服务器端
sudo apt-get install -y nfs-common         # 安装 NFS客户端

nfs服务器端，只在集群中某一台安装即可

创建nfs共享目录

mkdir -p /nfs/share
chmod -R 777 /nfs/share

修改配置 vim /etc/exports

# 当登录NFS主机使用共享目录的使用者是root时，其权限将被转换成为匿名使用者，通常它的UID与GID都会变成nobody身份,添加no_root_squash参数，确保root账户能用
/nfs/share *(rw,sync,no_root_squash)     # * 表示允许任何网段 IP 的系统访问该 NFS 目录

配置生效

exportfs -r
exportfs  # 查看生效

启动服务

sudo /etc/init.d/nfs-kernel-server restart

mount -t nfs 192.168.254.130:/nfs/share /nfsremote -o nolock

如果提示 mount.nfs: access denied by server while mounting
>
> 在服务器端 ``/etc/exports中加入insecure> > 如:/nfs/share *(insecure,rw,sync,no_root_squash)`

实例数据

echo "hello world" > /nfs/share/index.html

pod 挂载 nfs

架构图

pod_nfs.yaml:

apiVersion: v1
kind: Pod
metadata:
  name: nfs-testpod
  labels:
    app: nfs-testpod
spec:
  containers:
    - name: nfs-testpod
      image: nginx
      imagePullPolicy: IfNotPresent
      securityContext:
        privileged: true
      ports:
        - containerPort: 80
          hostPort: 8080   # 将该端口暴露在主机的 8080
      volumeMounts:
        - mountPath: /usr/share/nginx/html
          name: datadir
  restartPolicy: Always
  volumes:
    - name: datadir
      nfs:
        server: 192.168.254.133
        path: /nfs/share

验证结果:

$ k create -f pod_nfs.yaml

$ k get po -owide
NAME             READY   STATUS    RESTARTS   AGE   IP               NODE     NOMINATED NODE   READINESS GATES
nfs-testpod      1/1     Running   0          16m   10.244.196.134   node01   <none>           <none>

$ curl node01:8080
hello world

pvc 方式挂载 nfs

架构图

pod_nfs_pv_pvc.yaml:

# pv 分配资源
apiVersion: v1
kind: PersistentVolume
metadata:
  name: nfs-pv01
  labels:
    pv: nfs-pv01
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteMany
  # 挂载 nfs
  nfs:
    path: /nfs/share
    server: 192.168.254.133
---
# pvc 向一个 pv 去请求资源
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nfs-pvc01
  labels:
    pv: nfs-pvc01
spec:
  # 向 pv 请求的存储大小
  resources:
    requests:
      storage: 500Mi
  accessModes:
    - ReadWriteMany
  # 通过 label 选择 pv
  selector:
    matchLabels:
      pv: nfs-pv01
---
apiVersion: v1
kind: Pod
metadata:
  name: nfs-pv-pvc-pod
  labels:
    app: nfs-pv-pvc-pod
spec:
  containers:
    - name: nfs-pv-pvc-pod
      image: nginx
      imagePullPolicy: IfNotPresent
      ports:
        - containerPort: 80
          hostPort: 8081   # 暴露 8081 
      volumeMounts:
        - mountPath: /usr/share/nginx/html
          name: datadir
  restartPolicy: Always
  volumes:
    - name: datadir
      persistentVolumeClaim:
        claimName: nfs-pvc01

验证结果:

$ k get po -owide
NAME             READY   STATUS    RESTARTS   AGE   IP               NODE     NOMINATED NODE   READINESS GATES
nfs-pv-pvc-pod   1/1     Running   0          97s   10.244.196.135   node01   <none>           <none>
nfs-testpod      1/1     Running   0          16m   10.244.196.134   node01   <none>           <none>

$ k get pv
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM               STORAGECLASS   VOLUMEATTRIBUTESCLASS   REASON   AGE
nfs-pv01   1Gi        RWX            Retain           Bound    default/nfs-pvc01                  <unset>                          8s
$ k get pvc
NAME        STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
nfs-pvc01   Bound    nfs-pv01   1Gi        RWX                           <unset>                 10s

$ curl node01:8081
hello world

注意: 1 个 pv 能绑定一个 pvc

storageclass 方式动态申请 pv

架构图

sc 要方式动态申请 pv, 需要一个与存储对应的 provisioner, 可以是云服务器的 provisioner. 参考

我们使用的是 nfs, 所以需要 nfs-provisioner

安装 nfs-provisioner

本次使用的是 nfs-provisioner 是 nfs subdir

# 通过 helm 安装, 安装 helm
wget https://get.helm.sh/helm-v3.7.0-linux-amd64.tar.gz 
tar zxvf helm-v3.7.0-linux-amd64.tar.gz
mv linux-amd64/helm /usr/local/bin/


$ helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner/
$ helm install nfs-subdir-external-provisioner nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
    --set nfs.server=192.168.254.133 \
    --set nfs.path=/nfs/share
# 也可以 helm pull nfs-subdir-external-provisioner/nfs-subdir-external-provisioner 后修改 values 的值
# 推荐 helm pull 下来后修改镜像地址 aifeierwithinmkt/nfs-subdir-external-provisioner (无法拉取镜像, 我推到 dockerhub的镜像)
NAME: nfs-subdir-external-provisioner
LAST DEPLOYED: Sun Jan 28 15:39:16 2024
NAMESPACE: default
STATUS: deployed
REVISION: 1
TEST SUITE: None

# 查看 pod
$ k get po -owide
NAME                                              READY   STATUS    RESTARTS   AGE   IP               NODE     NOMINATED NODE   READINESS GATES
nfs-pv-pvc-pod                                    1/1     Running   0          50m   10.244.196.135   node01   <none>           <none>
nfs-subdir-external-provisioner-f8db66c64-cgpqk   1/1     Running   0          52s   10.244.196.137   node01   <none>           <none>
nfs-testpod                                       1/1     Running   0          65m   10.244.196.134   node01   <none>           <none>

# 我们需要从 pod 中获取 provisioner 的地址(pod 的环境变量), 用作 sc 的 provisioner 地址
k describe po nfs-subdir-external-provisioner-f8db66c64-cgpqk | grep PROVISIONER_NAME

pod_nfs_sc_pvc.yaml:

# 构建 storageclass
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-sc
provisioner: cluster.local/nfs-subdir-external-provisioner
mountOptions:
  - nfsvers=4
#parameters:
#  server: nfs-server.example.com
#  path: /share
#  readOnly: "false"
---
# pvc 向一个 pv 去请求资源
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: nfs-pvc02
  labels:
    pv: nfs-pvc02
spec:
  # 向 pv 请求的存储大小
  resources:
    requests:
      storage: 500Mi
  accessModes:
    - ReadWriteMany
  # 指定 storageclass
  storageClassName: nfs-sc
  # 通过 label 选择 pv
#  selector:
#    matchLabels:
#      pv: nfs-pv01
---
apiVersion: v1
kind: Pod
metadata:
  name: nfs-sc-pvc-pod
  labels:
    app: nfs-sc-pvc-pod
spec:
  containers:
    - name: nfs-sc-pvc-pod
      image: nginx
      imagePullPolicy: IfNotPresent
      ports:
        - containerPort: 80
          hostPort: 8082
      volumeMounts:
        - mountPath: /usr/share/nginx/html
          name: datadir
  restartPolicy: Always
  volumes:
    - name: datadir
      persistentVolumeClaim:
        claimName: nfs-pvc02

验证结果:

$ k get po -owide
NAME                                              READY   STATUS    RESTARTS   AGE   IP               NODE     NOMINATED NODE   READINESS GATES
nfs-sc-pvc-pod                                    1/1     Running   0          10s   10.244.196.138   node01   <none>           <none>

$ k get pvc
NAME        STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
nfs-pvc02   Bound    pvc-7ebac745-38f2-4ea7-8d18-0465f6fdf2d1   500Mi      RWX            nfs-sc         <unset>                 2m4s

$ curl node01:8082
hello world

参考

https://kubernetes.io/zh-cn/docs/concepts/storage/storage-classes/#nfs