k8s之存储卷local PV

一、简介

• local能够作为PV使用的本地存储卷。
• local卷插件用于将本地存储设备(如磁盘、分区或目录) 配置为卷。
• hostPath卷在Pod被重建后可能被调试至其它节点而无法再次使用此前的数据，而基于local卷，调度器能自行完成调度绑定。
• 基于local的PV，需要管理员通过nodeAffinit声明其定义在的节点。
• local 卷只能用作静态创建的持久卷。不支持动态配置。

二、创建local PV
1、创建存储类

• 配置PVC绑定local PV时，通常要创建个StorageClass。

root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# cat storageclass-local.yaml 
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: local
provisioner: kubernetes.io/no-provisioner
volumeBindingMode: WaitForFirstConsumer

root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl apply -f storageclass-local.yaml 
storageclass.storage.k8s.io/local created
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl get sc
NAME               PROVISIONER                    RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
local              kubernetes.io/no-provisioner   Delete          WaitForFirstConsumer   false                  4s

2、创建率属于存储类的PV

• 进入节点1准备本地磁盘目录，作为local pv的存储卷

root@k8s-node01:~# mkdir /disks/vol1 -pv
mkdir: created directory '/disks'
mkdir: created directory '/disks/vol1'
root@k8s-node01:~# ls /disks/vol1/

• 创建PV

root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# cat local-pv-demo.yaml 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: local-pv-demo
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  storageClassName: local
  local:
    path: /disks/vol1                                #将本地磁盘作为目录,事先存在。
  nodeAffinity:
    required:
      nodeSelectorTerms:
      - matchExpressions:
        - key: kubernetes.io/hostname                #匹配的节点标签
          operator: In
          values:
          - k8s-node01                               #PV绑定的节点名称
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl apply -f local-pv-demo.yaml 
persistentvolume/local-pv-demo created
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl get pv 
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                  STORAGECLASS       REASON   AGE
local-pv-demo                              5Gi        RWO            Delete           Available                          local                       4s

3、创建PVC

• 由于PVC是创建的延迟绑定的，所以创建完成后处于Pending 状态

root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# cat pvc-localpv-demo.yaml 
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: pvc-localpv-demo
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: local
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl apply -f pvc-localpv-demo.yaml 
persistentvolumeclaim/pvc-localpv-demo created
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl get pvc
NAME               STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS       AGE
data-mysql-0       Bound     pvc-7785640d-623d-4dd6-90ff-0ce026254733   10Gi       RWO            openebs-hostpath   5d13h
pvc-demo           Bound     pv-nfs-demo                                5Gi        RWX                               96m
pvc-localpv-demo   Pending                                                                        local              6s

三、Pod消费PVC

• 由于可消费的PVC只在节点1，所以Pod被调度到节点1

root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# cat pod-with-localpv.yaml 
apiVersion: v1
kind: Pod
metadata:
  name: pod-with-localpv
spec:
  containers:
  - name: redis
    image: redis:7-alpine
    ports: 
    - containerPort: 6379
      name: redis
    volumeMounts: 
    - mountPath: "/data"
      name: data
  volumes:
    - name: data
      persistentVolumeClaim:
        claimName: pvc-localpv-demo
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl apply -f pod-with-localpv.yaml 
pod/pod-with-localpv created
root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl get pod -o wide
NAME                     READY   STATUS    RESTARTS      AGE     IP            NODE         NOMINATED NODE   READINESS GATES
pod-with-localpv         1/1     Running   0             22s     10.244.2.32   k8s-node01   <none>           <none>

• PVC也被Bound

root@k8s-master01:~/learning-k8s/examples/volumes/local-pv-demo# kubectl get pvc
NAME               STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS       AGE
data-mysql-0       Bound    pvc-7785640d-623d-4dd6-90ff-0ce026254733   10Gi       RWO            openebs-hostpath   5d13h
pvc-demo           Bound    pv-nfs-demo                                5Gi        RWX                               104m
pvc-localpv-demo   Bound    local-pv-demo                              5Gi        RWO            local              7m45s