K8s--06 K8s数据持久化

K8s数据持久化

数据持久化 Volume介绍

Volume介绍：
Volume是Pad中能够被多个容器访问的共享目录
Kubernetes中的Volume不Pad生命周期相同，但不容器的生命周期丌相关
Kubernetes支持多种类型的Volume，并且一个Pod可以同时使用任意多个Volume
Volume类型包括:
- EmptyDir：Pod分配时创建， K8S自动分配，当Pod被移除数据被清空。用于临时空间等。
- hostPath：为Pod上挂载宿主机目录。用于持久化数据。
- nfs：挂载相应磁盘资源。

1.EmptyDir实验

EmptyDir实验
cat >emptyDir.yaml <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: busybox-empty
spec:
  containers:
  - name: busybox-pod
    image: busybox
    volumeMounts:
    - mountPath: /data/busybox/
      name: cache-volume
    command: ["/bin/sh","-c","while true;do echo $(date) >> /data/busybox/index.html;sleep 3;done"]
  volumes:
  - name: cache-volume
    emptyDir: {}
EOF

2.hostPath实验

hostPath实验
1.发现的问题：
- 目录必须存在才能创建
- POD不固定会创建在哪个Node上，数据不统一

2.type类型说明
https://kubernetes.io/docs/concepts/storage/volumes/#hostpath

DirectoryOrCreate  目录不存在就自动创建
Directory      目录必须存在
FileOrCreate       文件不存在则创建
File           文件必须存在

3.根据Node标签选择POD创建在指定的Node上
方法1: 直接选择Node节点名称
apiVersion: v1
kind: Pod
metadata:
  name: busybox-nodename
spec:
  nodeName: node2
  containers:
  - name: busybox-pod
    image: busybox
    volumeMounts:
    - mountPath: /data/pod/
      name: hostpath-volume
    command: ["/bin/sh","-c","while true;do echo $(date) >> /data/pod/index.html;sleep 3;done"]
  volumes:
  - name: hostpath-volume
    hostPath:
      path: /data/node/
      type: DirectoryOrCreate 


方法2: 根据Node标签选择Node节点
kubectl label nodes node3 disktype=SSD

apiVersion: v1
kind: Pod
metadata:
  name: busybox-nodename
spec:
  nodeSelector:
    disktype: SSD
  containers:
  - name: busybox-pod
    image: busybox
    volumeMounts:
    - mountPath: /data/pod/
      name: hostpath-volume
    command: ["/bin/sh","-c","while true;do echo $(date) >> /data/pod/index.html;sleep 3;done"]
  volumes:
  - name: hostpath-volume
    hostPath:
      path: /data/node/
      type: DirectoryOrCreate 


4.实验-编写mysql的持久化deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql-dp
  namespace: default
spec:
  selector:
    matchLabels:
      app: mysql 
  replicas: 1
  template: 
    metadata:
      name: mysql-pod
      namespace: default
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql-pod
        image: mysql:5.7 
        ports:
        - name: mysql-port
          containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456" 
        volumeMounts:
        - mountPath: /var/lib/mysql
          name: mysql-volume
      volumes:
      - name: mysql-volume
        hostPath:
          path: /data/mysql
          type: DirectoryOrCreate 
      nodeSelector:
        disktype: SSD

3.PV和PVC

PV和PVC
1.master节点安装nfs
yum install nfs-utils -y
mkdir /data/nfs-volume -p
vim /etc/exports
/data/nfs-volume 10.0.0.0/24(rw,async,no_root_squash,no_all_squash)
systemctl start rpcbind
systemctl start nfs
showmount -e 127.0.0.1

2.所有node节点安装nfs
yum install nfs-utils.x86_64 -y
showmount -e 10.0.0.11

3.编写并创建nfs-pv资源
cat >nfs-pv.yaml <<EOF
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv01
spec:
  capacity:
    storage: 5Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  storageClassName: nfs
  nfs:
    path: /data/nfs-volume/mysql
    server: 10.0.0.11
EOF

kubectl create -f nfs-pv.yaml
kubectl get persistentvolume

3.创建mysql-pvc
cat >mysql-pvc.yaml <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pvc 
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: nfs
EOF
kubectl create -f mysql-pvc.yaml
kubectl get pvc

4.创建mysql-deployment
cat >mysql-dp.yaml <<EOF
apiVersion: apps/v1
kind: Deployment 
metadata:
  name: mysql
spec:
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"
        volumeMounts:
        - name: mysql-pvc
          mountPath: /var/lib/mysql
        - name: mysql-log
          mountPath: /var/log/mysql
      volumes:
      - name: mysql-pvc
        persistentVolumeClaim:
          claimName: mysql-pvc
      - name: mysql-log
        hostPath:
          path: /var/log/mysql
      nodeSelector:
        disktype: SSD
EOF

kubectl create -f mysql-dp.yaml
kubectl get pod -o wide 

5.测试方法
1.创建nfs-pv
2.创建mysql-pvc
3.创建mysql-deployment并挂载mysq-pvc
4.登陆到mysql的pod里创建一个数据库
5.将这个pod删掉，因为deployment设置了副本数，所以会自动再创建一个新的pod
6.登录这个新的pod，查看刚才创建的数据库是否依然能看到
7.如果仍然能看到，则说明数据是持久化保存的

6.accessModes字段说明
ReadWriteOnce 单路读写
ReadOnlyMany  多路只读
ReadWriteMany 多路读写
resources 资源的限制，比如至少5G

7.volumeName精确匹配
#capacity 限制存储空间大小
#reclaim policy pv的回收策略
#retain  pv被解绑后上面的数据仍保留
#recycle pv上的数据被释放
#delete  pvc和pv解绑后pv就被删除
备注：用户在创建pod所需要的存储空间时，前提是必须要有pv存在
才可以，这样就不符合自动满足用户的需求，而且之前在k8s 9.0
版本还可删除pv，这样造成数据不安全性