K8s数据持久化StorageClass

一、简介

1.1什么是StorageClass

Kubernetes提供了一套可以自动创建PV的机制，即：Dynamic Provisioning。而这个机制的核心在于StorageClass这个API对象。

StorageClass对象会定义下面两部分内容:

• PV的属性。比如，存储类型，Volume的大小等。
• 创建这种PV需要用到的存储插件，即存储制备器。
  有了这两个信息之后，Kubernetes就能够根据用户提交的PVC，找到一个对应的StorageClass，之后Kubernetes就会调用该StorageClass声明的存储插件，进而创建出需要的PV。

但是其实使用起来是一件很简单的事情，你只需要根据自己的需求，编写YAML文件即可，然后使用kubectl create命令执行即可。

---

1.2StorageClass架构

在动态资源供应模式下，通过StorageClass和PVC完成资源动态绑定（系统自动生成PV），并供Pod使用的存储管理机制。

---

二、创建

2.1创建StorageClass存储服务

利用nfs-client-provisioner来生成一个基于nfs的StorageClass，部署配置yaml配置如下，保持为nfs-sc.yaml：

apiVersion: v1
kind: ServiceAccount
metadata:
  name: nfs-client-provisioner
  namespace: kube-system

---
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"]
  - apiGroups: [""]
    resources: ["endpoints"]
    verbs: ["get", "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: kube-system
roleRef:
  kind: ClusterRole
  name: nfs-client-provisioner-runner
  apiGroup: rbac.authorization.k8s.io

---
kind: Deployment
apiVersion: apps/v1
metadata:
  name: nfs-provisioner-01
  namespace: kube-system
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: nfs-provisioner-01
  template:
    metadata:
      labels:
        app: nfs-provisioner-01
    spec:
      serviceAccountName: nfs-client-provisioner
      containers:
        - name: nfs-client-provisioner
          image: jmgao1983/nfs-client-provisioner:latest
          imagePullPolicy: IfNotPresent
          volumeMounts:
            - name: nfs-client-root
              mountPath: /persistentvolumes
          env:
            - name: PROVISIONER_NAME
              value: nfs-provisioner-01  # 此处供应者名字供storageclass调用
            - name: NFS_SERVER
              value: 10.7.48.223   # 填入NFS的地址
            - name: NFS_PATH
              value: /data/lnmp/test  # 填入NFS挂载的目录
      volumes:
        - name: nfs-client-root
          nfs:
            server: 10.7.48.223   # 填入NFS的地址
            path: /data/lnmp/test   # 填入NFS挂载的目录

---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-test
provisioner: nfs-provisioner-01
# Supported policies: Delete、 Retain ， default is Delete
reclaimPolicy: Retain

#部署服务
[root@k8smaster StorageClass]# kubectl apply -f nfs-sc.yaml
#因为是偏向系统层面的服务所以放到了kube-system命名空间
[root@k8smaster StorageClass]# kubectl -n kube-system get pod
#查看sc状态
[root@k8smaster StorageClass]# kubectl get sc
NAME       PROVISIONER          RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
nfs-test   nfs-provisioner-01   Retain          Immediate           false             2m43s

---

2.2 基于SC创建PVC测试

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: pvc-sc
spec:
  storageClassName: nfs-test
  accessModes:
    - ReadWriteMany
  resources:
    requests:
      storage: 1Mi

[root@k8smaster StorageClass]# kubectl apply -f pvc-sc.yaml
persistentvolumeclaim/pvc-sc created
#查看pv和pvc
[root@k8smaster StorageClass]# kubectl get pv
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM                                           STORAGECLASS   REASON   AGE
pvc-bc40c73b-cf4a-4c2d-a551-c2fdbd7e245a   1Mi        RWX            Retain        Bound      default/pvc-sc                                  nfs-test             52s
[root@k8smaster StorageClass]# kubectl get pvc
NAME     STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
pvc-sc   Bound    pvc-bc40c73b-cf4a-4c2d-a551-c2fdbd7e245a   1Mi        RWX         nfs-test       2m31s

使用nginx测试

---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx
        volumeMounts:    # 我们这里将nginx容器默认的页面目录挂载
          - name: html-files
            mountPath: "/usr/share/nginx/html"
      volumes:
        - name: html-files
          persistentVolumeClaim:
            claimName: pvc-sc

[root@k8smaster StorageClass]# kubectl apply -f nginx.yaml
deployment.apps/nginx created
#查看pod是否运行
[root@k8smaster StorageClass]# kubectl get po
NAME                     READY   STATUS    RESTARTS   AGE
nginx-76f5df5fcf-f8x9m   1/1     Running   0          46s
#进入pod测试是否设置成功
[root@k8smaster StorageClass]# kubectl exec -it nginx-76f5df5fcf-f8x9m -- bash
root@nginx-76f5df5fcf-f8x9m:/# echo 'test' > /usr/share/nginx/html/index.html
root@nginx-76f5df5fcf-f8x9m:/# exit
exit
[root@k8smaster StorageClass]# cat /data/lnmp/test/default-pvc-sc-pvc-bc40c73b-cf4a-4c2d-a551-c2fdbd7e245a/index.html
test