volume数据卷管理

一、volume介绍
用于实现数据的持久化存储
Kubernetes支持多种类型的卷，例如EmptyDir、HostPath、nfs、glusterfs、ceph等

二、emptyDir
创建Pod时，Pod运行的node节点会创建临时卷，并将卷挂载到Pod指定的目录中
临时卷存放目录
/var/lib/kubelet/pods//volumes/kubernetes.io~empty-dir/卷名称
Pod宕机销毁后，该临时卷中的数据会随之被删除

apiVersion: apps/v1
kind: Deployment
metadata:
    name: test1-deploy
spec:
    replicas: 2
    selector:
         matchLabels:
             app: test1-pod
    template:
       metadata:
           labels:
              app: test1-pod
       spec:
           containers:
           - name: test1-pod
             image: busybox
             imagePullPolicy: IfNotPresent
             command:
             - sleep
             - "3600"
             volumeMounts:
                - name: test1-volume
                  mountPath: /test1
           volumes:
               - name: test1-volume
                 emptyDir: {}

三、hostPath
创建Pod时，Pod运行的node节点会在本地创建目录，并该目录挂载到Pod中
Pod宕机后，宿主机对应目录中的文件不会消失

apiVersion: apps/v1
kind: Deployment
metadata:
    name: test2-deploy
    labels:
        app: test2-deploy
spec:
    replicas: 2
    selector:
         matchLabels:
             app: test2-pod
    template:
       metadata:
           labels:
              app: test2-pod
       spec:
           containers:
           - name: test2-pod
             image: busybox
             imagePullPolicy: IfNotPresent
             command:
             - sleep
             - "3600"
             volumeMounts:
                - name: test2-volume
                  mountPath: /test1
           volumes:
               - name: test2-volume
                 hostPath:
                    path: /data

四、基于nfs的网络卷

apiVersion: apps/v1
kind: Deployment
metadata:
    name: test3-deploy
    labels:
        app: test3-deploy
spec:
    replicas: 2
    selector:
         matchLabels:
             app: test3-pod
    template:
       metadata:
           labels:
              app: test3-pod
       spec:
           containers:
           - name: test3-pod
             image: busybox
             imagePullPolicy: IfNotPresent
             command:
             - sleep
             - "3600"
             volumeMounts:
                - name: test3-volume
                  mountPath: /test1
           volumes:
               - name: test3-volume
                 nfs:
                     server: "192.168.140.11"
                     path: "/data"

五、PV与PVC 持久卷

1、PV、PVC介绍
PV PersistentVolume
后端真实存储空间的映射

PVC PersistentVolumeClain
使用存储空间的申请

使用流程
创建PV标识真实的存储空间
创建PVC发送申请存储空间的请求，K8S集群会自动在PV、PVC间建立映射关系
建立映射关系：
依靠存储空间的大小
依靠PV的访问模式
创建POD时绑定PVC，实现持久化

1、创建PV
apiVersion: v1
kind: PersistentVolume
metadata:
    name: nfs-data1
spec:
    capacity:
       storage: 2G
    accessModes:
       - ReadWriteMany
    persistentVolumeReclaimPolicy: Recycle
    nfs:
        server: 192.168.140.13
        path: /data1