一、规划

我们接着之前的文档的架构规划进行下面的操作。

IP 角色
192.168.1.200 k8s-master
192.168.1.201 k8s-node01
192.168.1.202 k8s-node02
192.168.1.203 k8s-store

我们演示如何为 MySQL 数据库提供持久化存储,主要分为下面几个步骤:

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

二、部署

1、创建 PV 和 PVC

我们 PV 的配置文件mysql-pv.yaml如下:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
  - ReadWriteOnce
  nfs:
    path: /data/volumes/mysql-pv
    server: 192.168.1.203

创建 PV。

[root@master ~]# kubectl apply -f mysql-pv.yaml 
persistentvolume/mysql-pv created
[root@master ~]# kubectl get pv
NAME       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM   STORAGECLASS   REASON   AGE
mysql-pv   1Gi        RWO            Retain           Available                                   7s

PVC 的配置文件mysql-pvc.yaml内容如下:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: mysql-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

创建 PVC。

[root@master ~]# kubectl apply -f mysql-pvc.yaml 
persistentvolumeclaim/mysql-pvc created
[root@master ~]# kubectl get pvc
NAME        STATUS   VOLUME     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mysql-pvc   Bound    mysql-pv   1Gi        RWO                           7s

2、部署 MySQL

MySQL 的配置文件mysql.yaml如下:

apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
  - port: 3306
  selector:
    app: mysql
---
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: mysql:5.6
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: password
        ports:
        - name: mysql
          containerPort: 3306
        volumeMounts:
        - name: mysql-persistent-storage
          mountPath: /var/lib/mysql
      volumes:
      - name: mysql-persistent-storage
        persistentVolumeClaim:
          claimName: mysql-pvc

PVC mysql-pvc Bound 的 PV mysql-pv 将被 mount 到 MySQL 的数据目录 /var/lib/mysql

[root@master ~]# kubectl apply -f mysql.yaml 
service/mysql created
deployment.extensions/mysql created
[root@master ~]# kubectl get pod -o wide
NAME                     READY   STATUS    RESTARTS   AGE   IP            NODE     NOMINATED NODE   READINESS GATES
mysql-7686899cf9-d4m42   1/1     Running   0          62s   10.244.2.17   node02   <none>           <none>

3、更新 MySQL 数据

MySQL 被部署到 k8s-node02,下面通过客户端访问 Service mysql:

[root@master ~]# kubectl run -it --rm --image=mysql:5.6 --restart=Never mysql-client -- mysql -h mysql -ppassword
If you don't see a command prompt, try pressing enter.
mysql>

我们在mysql库中创建一个表myid,然后在表里新增几条数据。

mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> create table myid( id int(4) );
Query OK, 0 rows affected (0.04 sec)

mysql> insert myid values( 111 );
Query OK, 1 row affected (0.00 sec)

mysql> select * from myid;
+------+
| id   |
+------+
|  111 |
+------+
1 row in set (0.00 sec)

4、故障转移

我们现在把 node02 机器关机,模拟节点宕机故障。

一段时间之后,Kubernetes 将 MySQL 迁移到 k8s-node01

[root@master ~]# kubectl get pod -o wide
NAME                     READY   STATUS        RESTARTS   AGE   IP            NODE     NOMINATED NODE   READINESS GATES
mysql-7686899cf9-8z6tc   1/1     Running       0          21s   10.244.1.19   node01   <none>           <none>
mysql-7686899cf9-d4m42   1/1     Terminating   0          23m   10.244.2.17   node02   <none>           <none>

验证数据的一致性。

[root@master ~]# kubectl run -it --rm --image=mysql:5.6 --restart=Never mysql-client -- mysql -h mysql -ppassword
If you don't see a command prompt, try pressing enter.
mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from myid;
+------+
| id   |
+------+
|  111 |
+------+
1 row in set (0.00 sec)

MySQL 服务恢复,数据也完好无损,我们可以可以在存储节点上面查看一下生成的数据库文件。

[root@datanode03 mysql-pv]# ll
总用量 110604
-rw-rw---- 1 systemd-bus-proxy ssh_keys       56 12月 14 09:53 auto.cnf
-rw-rw---- 1 systemd-bus-proxy ssh_keys 12582912 12月 14 10:15 ibdata1
-rw-rw---- 1 systemd-bus-proxy ssh_keys 50331648 12月 14 10:15 ib_logfile0
-rw-rw---- 1 systemd-bus-proxy ssh_keys 50331648 12月 14 09:53 ib_logfile1
drwx------ 2 systemd-bus-proxy ssh_keys     4096 12月 14 10:05 mysql
drwx------ 2 systemd-bus-proxy ssh_keys     4096 12月 14 09:53 performance_schema