MySQL基于PV和PVC实现数据持久化

演示如何为 MySQL 数据库提供持久化存储，步骤为：

创建 PV 和 PVC。
部署 MySQL。
向 MySQL 添加数据。
模拟节点宕机故障，Kubernetes 将 MySQL 自动迁移到其他节点。
验证数据一致性。

第一步：控制节点部署NFS

[root@ken1 ~]# cat /etc/exports
/ken/mysql *(rw,no_root_squash)

注意：这里必须加入no_root_squash意思是不降低root的权限，不加这个报错如下：

chown: changing ownership of '/var/lib/mysql/': Operation not permitted

no_root_squash 访问共享目录时，用户如果是root权限，对共享目录也具有root权限

root_squash 如果访问共享目录是root的权限用户，对共享目录的权限会被压缩为nfsnobody用户的权

all_squash 不管你访问共享目录的用户是谁，都必须压缩为nfsnobody用户的权限

第二步：首先创建 PV 和 PVC，配置如下：

pv.yml

[root@ken1 ~]# cat pv.yml 
apiVersion: v1
kind: PersistentVolume
metadata:
 name: mypv
spec:
 capacity:
 storage: 1Gi
 accessModes: 
 - ReadWriteMany
 nfs:
 path: /ken
 server: 192.168.64.11

pvc.yml

[root@ken1 ~]# cat pvc.yml 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
 name: mypvc
spec:
 volumeName: mypv
 accessModes:
 - ReadWriteMany
 resources:
 requests:
 storage: 1Gi

第三步：创建pv和pvc

[root@ken1 ~]# kubectl apply -f pv.yml 
persistentvolume/mypv unchanged
[root@ken1 ~]# kubectl get pv
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
mypv 1Gi RWX Retain Available 8d
[root@ken1 ~]# kubectl apply -f pvc.yml 
persistentvolumeclaim/mypvc created
[root@ken1 ~]# kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
mypvc Bound mypv 1Gi RWX 3s

第四步：接下来部署 MySQL，配置文件如下

[root@ken1 ~]# cat mysql.yml
apiVersion: v1
kind: Service
metadata:
 name: mysql-svc
spec:
 type: NodePort
 selector:
 run: mysql
 ports:
 - port: 80
 targetPort: 3306
 NodePort: 3306
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
 name: mysql
spec:
 template:
 metadata:
 labels:
 run: mysql
 spec:
 containers:
 - name: mysql
 image: mysql
 imagePullPolicy: IfNotPresent
 env:
 - name: MYSQL_ROOT_PASSWORD
 value: ken 
 ports:
 - name: mysql
 containerPort: 3306
 volumeMounts:
 - name: mysql
 mountPath: /var/lib/mysql
 volumes:
 - name: mysql
 persistentVolumeClaim:
 claimName: mypvc

第五步：查看pod

[root@ken1 ~]# kubectl get po -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
mysql-587dbd4dd6-79tn5 1/1 Running 0 9m20s 10.244.1.60 ken2 <none> <none>

第六步：登入数据库创建数据库ken

[root@ken1 ~]# kubectl exec -it mysql-587dbd4dd6-79tn5 bash
root@mysql-587dbd4dd6-79tn5:/# mysql -uroot -pken
mysql> create database ken;
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ken |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.00 sec)

第七步：关闭运行该pod的ken2节点，模拟故障

poweroff

第八步:一段时间后k8s把pod移动到ken3节点

[root@ken1 ~]# kubectl get po -o wide -w
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
mysql-587dbd4dd6-79tn5 1/1 Running 0 14m 10.244.1.60 ken2 <none> <none>
mysql-587dbd4dd6-79tn5 1/1 Terminating 0 18m 10.244.1.60 ken2 <none> <none>
mysql-587dbd4dd6-gxnpq 0/1 Pending 0 0s <none> <none> <none> <none>
mysql-587dbd4dd6-gxnpq 0/1 Pending 0 0s <none> ken3 <none> <none>
mysql-587dbd4dd6-gxnpq 0/1 ContainerCreating 0 0s <none> ken3 <none> <none>
mysql-587dbd4dd6-gxnpq 1/1 Running 0 3s 10.244.2.139 ken3 <none> <none>

第九步：在ken3节点登录数据库验证数据一致性

[root@ken3 ~]# docker exec -it 2aaf1b234ebf bash
root@mysql-587dbd4dd6-gxnpq:/# mysql -uroot -pken
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| ken |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.02 sec)

MySQL 服务恢复，数据也完好无损。

PV和PVC实现Pod自动迁移、MySQL数据持久化

MySQL基于PV和PVC实现数据持久化