前言：

k8s集群可以快速的部署各种服务，而MySQL作为有状态服务，必须要提供数据持久化存储，说人话就是volume。

在k8s中volume可以是本地目录提供，也可以是动态的由网络存储比如nfs或者块存储服务（比如，ceph，iscsi等等）提供，本文将使用nfs网络存储服务，动态的做这个volume持久化。

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环境介绍：

实验环境应该是有一个正常运行的k8s环境，我的k8s版本是1.19.4

[root@master ~]# k version
Client Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.4", GitCommit:"d360454c9bcd1634cf4cc52d1867af5491dc9c5f", GitTreeState:"clean", BuildDate:"2020-11-11T13:17:17Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"19", GitVersion:"v1.19.3", GitCommit:"1e11e4a2108024935ecfcb2912226cedeafd99df", GitTreeState:"clean", BuildDate:"2020-10-14T12:41:49Z", GoVersion:"go1.15.2", Compiler:"gc", Platform:"linux/amd64"}

集群已经正常运行了 

[root@master ~]# k get po -A
NAMESPACE              NAME                                                 READY   STATUS             RESTARTS   AGE
database               mysql-7c545744db-xzvnl                               1/1     Running            2          23h
database               mysql2-5db57c8bc8-xrnz6                              1/1     Running            1          13h
ingress-nginx          c7n3-ingress-nginx-controller-kmhz9                  1/1     Running            8          5d10h
ingress-nginx          c7n3-ingress-nginx-controller-z84cg                  1/1     Running            10         4d13h
ingress-nginx          c7n3-ingress-nginx-defaultbackend-7d64b4f74f-t7q7p   1/1     Running            7          4d
kube-system            coredns-6c76c8bb89-qt6zj                             1/1     Running            12         5d15h
kube-system            coredns-6c76c8bb89-r5vhq                             1/1     Running            12         5d15h
kube-system            etcd-c7n.gzinfo                                      1/1     Running            13         6d21h
kube-system            kube-apiserver-c7n.gzinfo                            1/1     Running            13         6d21h
kube-system            kube-controller-manager-c7n.gzinfo                   1/1     Running            14         6d21h
kube-system            kube-flannel-ds-d8sk8                                1/1     Running            8          4d14h
kube-system            kube-flannel-ds-jmnqj                                1/1     Running            8          4d13h
kube-system            kube-flannel-ds-lv57p                                1/1     Running            15         6d20h
kube-system            kube-proxy-dkxqz                                     1/1     Running            11         6d21h
kube-system            kube-proxy-llxrd                                     1/1     Running            14         6d21h
kube-system            kube-proxy-m49g2                                     1/1     Running            8          4d14h
kube-system            kube-scheduler-c7n.gzinfo                            1/1     Running            14         6d21h

集群所用网段是192.168.217.0/24 

nfs的配置：

[root@master ~]# cat /etc/exports
/data/k8s 10.244.0.0/16(rw,no_root_squash,no_subtree_check) 192.168.217.16(rw,no_root_squash,no_subtree_check) 192.168.217.0/24(rw,no_root_squash,no_subtree_check)
/data/nfs-sc  10.244.0.0/16(rw,no_root_squash,no_subtree_check) 192.168.217.16(rw,no_root_squash,no_subtree_check) 192.168.217.0/24(rw,no_root_squash,no_subtree_check)

 

实验步骤：

一，

查询StorageClass的name

[root@master ~]# k get sc -A
NAME              PROVISIONER                           RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
mynfs             mynfs                                 Delete          Immediate           true                   16h
nfs (default)     nfs                                   Delete          Immediate           true                   16h
nfs-provisioner   choerodon.io/nfs-client-provisioner   Delete          Immediate           false                  4d8h
nfs-sc            storage.pri/nfs                       Delete          Immediate           true                   17h

 可以看到nfs是我设定的默认StorageClass  名称。详细信息也验证了default是这个，（StorageClass怎么来的这就不说了，现在只说pvc绑定StorageClass）：

[root@master ~]# k describe sc nfs
Name:            nfs
IsDefaultClass:  Yes
Annotations:     kubectl.kubernetes.io/last-applied-configuration={"allowVolumeExpansion":true,"apiVersion":"storage.k8s.io/v1","kind":"StorageClass","metadata":{"annotations":{},"name":"nfs"},"provisioner":"nfs","reclaimPolicy":"Delete"}
,storageclass.kubernetes.io/is-default-class=true
Provisioner:           nfs
Parameters:            <none>
AllowVolumeExpansion:  True
MountOptions:          <none>
ReclaimPolicy:         Delete
VolumeBindingMode:     Immediate
Events:                <none>

二，

建立pvc并与nfs这个默认的StorageClass绑定

[root@master mysql]# cat pvc_mysql.yaml
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nfs-pvc-test
  namespace: database
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1.5Gi
  storageClassName: nfs

这里需要注意一点，有使用到namespace，因此，namespace需要建立，建立命令为：

k create namespace database

 

三，

建立pv

[root@master mysql]# cat pv_mysql.yaml
kind: PersistentVolume
apiVersion: v1
metadata:
  name: nfs-pv-test
spec:
  accessModes:
    - ReadWriteOnce      
  capacity:
    storage: 1.5Gi
  persistentVolumeReclaimPolicy: Recycle 
  storageClassName: nfs
  nfs:
    path: /data/nfs_sc/nfs-pv-test
    server: 192.168.217.16

 这里因为写的path是/data/nfs_sc/nfs-pv-test，因此，需要建立目录  mkdir /data/nfs_sc/nfs-pv-test&&chmod a+x /data/nfs_sc/nfs-pv-test

四，

部署MySQL

[root@master mysql]# cat deploy_mysql.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql2
  namespace: database
spec:
  selector:
    matchLabels:
      app: mysql2
  template:
    metadata:
      labels:
        app: mysql2
    spec:
      containers:
      - name: mysql2
        image: mysql:5.7.23
        env:                        
        - name: MYSQL_ROOT_PASSWORD
          value: "mima"
        ports:
        - containerPort: 3306
        volumeMounts:
        - name: nfs-pvc-test
          mountPath: /var/lib/mysql         
          subPath: mysql
      volumes:
      - name: nfs-pvc-test
        persistentVolumeClaim:
          claimName: nfs-pvc-test

五，

将部署的MySQL作为一个服务发布出去，从而可以进行维护

[root@master mysql]# cat svc_mysql.yaml
apiVersion: v1
kind: Service
metadata:
  name: mysql2
  namespace: database
spec:
  type: NodePort
  ports:
  - port: 3306
    targetPort: 3306
    nodePort: 32222
  selector:
    app: mysql2
  selector:
    app: mysql2

六，

开始部署，执行顺序没有规定，但最好是按这个来啦

k apply -f pv_mysql.yaml
k apply -f pvc_mysql.yaml
k apply -f deploy_mysql.yaml
k apply -f svc_mysql.yaml

 

七，

验证部署是否正确

 

 

查看pod 

[root@master mysql]# k get po -A
NAMESPACE              NAME                                                 READY   STATUS             RESTARTS   AGE
database               mysql-7c545744db-xzvnl                               1/1     Running            2          24h
database               mysql2-5db57c8bc8-xrnz6                              1/1     Running            1          13h

 查看端口

[root@master mysql]# netstat -antup |grep 32222
tcp        0      0 0.0.0.0:32222           0.0.0.0:*               LISTEN      3610/kube-proxy     

 这个32222端口是由kube-proxy代理发布的，因此，填写任意一个集群内的主机IP都可以访问到MySQL。（我的集群有三个服务器，ip是192.168.217.16/17/18）,随便写哪个IP都可以访问到MySQL。

查看pvc，第二行绑定的是nfs那个默认的

[root@master mysql]# k get pvc -A
NAMESPACE     NAME                               STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
database      mysql-pvc-test                     Bound    mysql-pv-test                              1Gi        RWO            nfs-provisioner   47h
database      nfs-pvc-test                       Bound    nfs-pv-test                                1536Mi     RWO            nfs               16h

至此，k8s集群内部署单机MySQL就成功了。