五、基于PVC+StatefulSet实现的MySQL主从架构

案例(部署mysql)本节使用 StatefulSet 控制器部署一个 MySQL 集群，然后进行宕机测试，观察集群是否可以正常恢复使用并且不丢失数据。
实现的集群有如下特征：
    是一个主从复制的 MySQL 集群
    1个主节点， 多个从节点
    从节点能够水平扩展
    所有的写操作，只能在主节点上执行
    读操作可以在所有节点上执行


#准备xtrabackup镜像
[root@localhost7C mysql]# docker pull registry.cn-hangzhou.aliyuncs.com/hxpdocker/xtrabackup:1.0
[root@localhost7C mysql]# docker tag c415dbd7af07     harobr.zzhz.com/linux39/xtrabackup:1.0
[root@localhost7C mysql]# docker push harobr.zzhz.com/linux39/xtrabackup:1.0
#准备mysql 镜像
[root@localhost7C mysql]# docker pull registry.cn-hangzhou.aliyuncs.com/acs-sample/mysql:5.7
[root@localhost7C mysql]# docker tag 54fec2fa59d0  harobr.zzhz.com/linux39/mysql:5.7
[root@localhost7C mysql]# docker push harobr.zzhz.com/linux39/mysql:5.7

 

2.安装nfs服务器，基于PV作为后端存储
[root@localhost7B ]# cat  /etc/exports
/data/k8sdata  *(rw,no_root_squash)

[root@localhost7B ~]# mkdir  /data/k8sdata/magedu/mysql-datadir-1
[root@localhost7B ~]# mkdir  /data/k8sdata/magedu/mysql-datadir-2
[root@localhost7B ~]# mkdir  /data/k8sdata/magedu/mysql-datadir-3
[root@localhost7B ~]# mkdir  /data/k8sdata/magedu/mysql-datadir-4


[root@localhost7B ]# systemctl  restart  nfs-server.service

 

[root@localhost7C mysql]# tree
├── mysql-configmap.yaml
├── mysql-services.yaml
├── mysql-statefulset.yaml
└── pv
　　└── mysql-persistentvolume.yaml

[root@localhost7C mysql]# cat pv/mysql-persistentvolume.yaml 
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-datadir-1
  namespace: magedu
spec:
  capacity:
    storage: 50Gi
  accessModes:
    - ReadWriteOnce
  nfs:
    path: /data/k8sdata/magedu/mysql-datadir-1 
    server: 192.168.80.110
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-datadir-2
  namespace: magedu
spec:
  capacity:
    storage: 50Gi
  accessModes:
    - ReadWriteOnce
  nfs:
    path: /data/k8sdata/magedu/mysql-datadir-2
    server: 192.168.80.110
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-datadir-3
  namespace: magedu
spec:
  capacity:
    storage: 50Gi
  accessModes:
    - ReadWriteOnce
  nfs:
    path: /data/k8sdata/magedu/mysql-datadir-3
    server: 192.168.80.110
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: mysql-datadir-4
  namespace: magedu
spec:
  capacity:
    storage: 50Gi
  accessModes:
    - ReadWriteOnce
  nfs:
    path: /data/k8sdata/magedu/mysql-datadir-4
    server: 192.168.80.110

#mysql主从的配置文件
[root@localhost7C mysql]# cat mysql-configmap.yaml 
apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql
  labels:
    app: mysql
data:
  master.cnf: |
    # Apply this config only on the master.
    [mysqld]
    log-bin
    log_bin_trust_function_creators=1
    lower_case_table_names=1
  slave.cnf: |
    # Apply this config only on slaves.
    [mysqld]
    super-read-only
    log_bin_trust_function_creators=1

@两个 Service 
[root@localhost7C mysql]# cat mysql-services.yaml 
# StatefulSet成员的稳定DNS项的无头服务。
apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
  clusterIP: None
  selector:
    app: mysql
---
#用于连接到任何MySQL实例进行读取的客户端服务。
#对于写入，您必须连接到master：mysql-0.mysql。
apiVersion: v1
kind: Service
metadata:
  name: mysql-read
  labels:
    app: mysql
spec:
#  type: NodePort
  ports:
  - name: mysql
    port: 3306
#    targetPort: 3306
#   nodePort: 33306
  selector:
    app: mysql

#yaml清单
[root@localhost7C mysql]# cat mysql-statefulset.yaml 
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  serviceName: mysql
  replicas: 2
  template:
    metadata:
      labels:
        app: mysql
    spec:
      #定义初始化容器 
      initContainers: 
      - name: init-mysql
        image: harbor.zzhz.com/linux39/mysql:5.7
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Generate mysql server-id from pod ordinal index.
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          echo [mysqld] > /mnt/conf.d/server-id.cnf
          # Add an offset to avoid reserved server-id=0 value.
          echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
          # Copy appropriate conf.d files from config-map to emptyDir.
          if [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf                   #调用emptyDir
          mountPath: /mnt/conf.d
        - name: config-map              #调用configmap
          mountPath: /mnt/config-map
          
      #定义初始化容器     
      - name: clone-mysql
        image: harbor.zzhz.com/linux39/xtrabackup:1.0 
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on master (ordinal index 0).
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          [[ $ordinal -eq 0 ]] && exit 0
          # Clone data from previous peer.
          ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
          # Prepare the backup.
          xtrabackup --prepare --target-dir=/var/lib/mysql
        volumeMounts:
        - name: data                    #调用PVC模版
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf                    #调用emptyDir
          mountPath: /etc/mysql/conf.d
         
         
      #定义容器    
      containers:
      - name: mysql
        image: harbor.zzhz.com/linux39/mysql:5.7
        env:
        - name: MYSQL_ALLOW_EMPTY_PASSWORD
          value: "1"
        ports:
        - name: mysql
          containerPort: 3306
        volumeMounts:
        - name: data                    #调用PVC模版
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf                    #调用emptyDir
          mountPath: /etc/mysql/conf.d
        resources:
          requests:
            cpu: 500m
            memory: 1Gi
        livenessProbe:
          exec:
            command: ["mysqladmin", "ping"]
          initialDelaySeconds: 30
          periodSeconds: 10
          timeoutSeconds: 5
        readinessProbe:
          exec:
            # Check we can execute queries over TCP (skip-networking is off).
            command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
          initialDelaySeconds: 5
          periodSeconds: 2
          timeoutSeconds: 1
          
      #定义容器    
      - name: xtrabackup
        image: harbor.zzhz.com/linux39/xtrabackup:1.0 
        ports:
        - name: xtrabackup
          containerPort: 3307
        command:
        - bash
        - "-c"
        - |
          set -ex
          cd /var/lib/mysql
          # Determine binlog position of cloned data, if any.
          if [[ -f xtrabackup_slave_info ]]; then
            # XtraBackup already generated a partial "CHANGE MASTER TO" query
            # because we're cloning from an existing slave.
            mv xtrabackup_slave_info change_master_to.sql.in
            # Ignore xtrabackup_binlog_info in this case (it's useless).
            rm -f xtrabackup_binlog_info
          elif [[ -f xtrabackup_binlog_info ]]; then
            # We're cloning directly from master. Parse binlog position.
            [[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || exit 1
            rm xtrabackup_binlog_info
            echo "CHANGE MASTER TO MASTER_LOG_FILE='${BASH_REMATCH[1]}',\
                  MASTER_LOG_POS=${BASH_REMATCH[2]}" > change_master_to.sql.in
          fi
          # Check if we need to complete a clone by starting replication.
          if [[ -f change_master_to.sql.in ]]; then
            echo "Waiting for mysqld to be ready (accepting connections)"
            until mysql -h 127.0.0.1 -e "SELECT 1"; do sleep 1; done
            echo "Initializing replication from clone position"
            # In case of container restart, attempt this at-most-once.
            mv change_master_to.sql.in change_master_to.sql.orig
            mysql -h 127.0.0.1 <<EOF
          $(<change_master_to.sql.orig),
            MASTER_HOST='mysql-0.mysql',
            MASTER_USER='root',
            MASTER_PASSWORD='',
            MASTER_CONNECT_RETRY=10;
          START SLAVE;
          EOF
          fi
          # Start a server to send backups when requested by peers.
          exec ncat --listen --keep-open --send-only --max-conns=1 3307 -c \
            "xtrabackup --backup --slave-info --stream=xbstream --host=127.0.0.1 --user=root"
        volumeMounts:
        - name: data                    #调用PVC模版
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf                    #调用emptyDir
          mountPath: /etc/mysql/conf.d
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
            
      volumes:
      - name: conf              #定义和启用emptyDir
        emptyDir: {}
      - name: config-map        #定义configmap
        configMap:
          name: mysql
          
  volumeClaimTemplates:         #定义PVC模版,
  - metadata:
      name: data                #PVC模版名称：PVC名称==PVC模版名称+pod名：如下面的data-mysql-0
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 10Gi





#查看sc，pv，pvc，pod，statefulset，svc
[root@localhost7C mysql]# kubectl  get pv,pvc,pod,svc,statefulsets  -A  -o wide
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                            STORAGECLASS   REASON   AGE     VOLUMEMODE
persistentvolume/mysql-datadir-1           50Gi       RWO            Retain           Bound       default/data-mysql-0                                     140m    Filesystem
persistentvolume/mysql-datadir-2           50Gi       RWO            Retain           Bound       default/data-mysql-1                                     140m    Filesystem
persistentvolume/mysql-datadir-3           50Gi       RWO            Retain           Available                                                            140m    Filesystem
persistentvolume/mysql-datadir-4           50Gi       RWO            Retain           Bound       default/data-mysql-2                                     140m    Filesystem


NAMESPACE   NAME                                            STATUS   VOLUME                    CAPACITY   ACCESS MODES   STORAGECLASS   AGE     VOLUMEMODE
default     persistentvolumeclaim/data-mysql-0              Bound    mysql-datadir-1           50Gi       RWO                           84m     Filesystem
default     persistentvolumeclaim/data-mysql-1              Bound    mysql-datadir-2           50Gi       RWO                           77m     Filesystem
default     persistentvolumeclaim/data-mysql-2              Bound    mysql-datadir-4           50Gi       RWO                           74m     Filesystem

NAMESPACE              NAME                                             READY   STATUS    RESTARTS   AGE    IP               NODE             NOMINATED NODE   READINESS GATES
default                pod/mysql-0                                      2/2     Running   0          30m    10.20.4.54       192.168.80.170   <none>           <none>
default                pod/mysql-1                                      2/2     Running   1          77m    10.20.5.50       192.168.80.160   <none>           <none>


NAMESPACE              NAME                                TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE    SELECTOR
default                service/mysql                       ClusterIP   None            <none>        3306/TCP         138m   app=mysql
default                service/mysql-read                  ClusterIP   10.10.124.250   <none>        3306/TCP         138m   app=mysql


NAMESPACE   NAME                     READY   AGE   CONTAINERS         IMAGES
default     statefulset.apps/mysql   2/2     79m   mysql,xtrabackup   harbor.zzhz.com/linux39/mysql:5.7,harbor.zzhz.com/linux39/xtrabackup:1.0





#测试短和长域名
FQDN：$(podname).(headless server name)  
FQDN：$(podname).(headless server name).namespace.svc.zzhz.local

[root@localhost7C mysql]# kubectl exec -it mysql-0  bash
root@mysql-0:/# hostname
mysql-0
root@mysql-0:/# ping mysql-1.mysql.default.svc.zzhz.local
root@mysql-0:/# ping mysql-0.mysql.default.svc.zzhz.local
root@mysql-0:/# ping mysql-1.mysql