Kubernetes部署MySQL8集群-

StorageClass

创建名叫mysql-sc的存储类

ConfigMap

新建文件： configmap.yml ，内容如下：

apiVersion: v1
data:
  master.cnf: |
    # Apply this config only on the master.
    [client]
    default-character-set=utf8mb4
    [mysql]
    default-character-set=utf8mb4
    [mysqld]
    log-bin
    binlog_expire_logs_seconds=2592000
    max_connections=10000
    default-time-zone='+8:00'
    character-set-client-handshake=FALSE
    character-set-server=utf8mb4
    collation-server=utf8mb4_unicode_ci
    init_connect='SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci'
  slave.cnf: |
    # Apply this config only on slaves.
    [client]
    default-character-set=utf8mb4
    [mysql]
    default-character-set=utf8mb4
    [mysqld]
    super-read-only
    max_connections=10000
    default-time-zone='+8:00'
    character-set-client-handshake=FALSE
    character-set-server=utf8mb4
    collation-server=utf8mb4_unicode_ci
    init_connect='SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci'
kind: ConfigMap
metadata:
  labels:
    app: mysql
  name: mysql

Headless Service

Headless Service 是有状态服务都需要，让其服务下的Pod能够彼此发现
新建文件： service.yml ，内容如下：

apiVersion: v1
kind: Service
metadata:
  name: mysql-svc-master
  labels:
    app: mysql
spec:
  selector:
    app: mysql
  ports:
  - port: 3306
    name: mysql
  clusterIP: None

SatefulSet

配置文件

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql-ss
spec: 
  selector: 
    matchLabels: 
      app: mysql 
  serviceName: mysql-svc-master
  replicas: 3
  template: 
    metadata:
      labels:
        app: mysql 
    spec:
      initContainers:
      - name: init-mysql
        image: mysql:8.0.19
        command:
        - bash
        - "-c"
        - |
          set ex
          # 从hostname中获取索引，比如(mysql-1)会获取(1)
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          echo [mysqld] > /mnt/conf.d/server-id.cnf
          # 为了不让server-id=0而增加偏移量
          echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
          # 拷贝对应的文件到/mnt/conf.d/文件夹中
          if [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: mzmuer/xtrabackup:1.0
        command:
        - bash
        - "-c"
        - |
          set -ex
          # 整体意思:
          # 1.如果是主mysql中的xtrabackup,就不需要克隆自己了,直接退出
          # 2.如果是从mysql中的xtrabackup,先判断是否是第一次创建，因为第二次重启本地就有数据库，无需克隆。若是第一次创建(通过/var/lib/mysql/mysql文件是否存在判断),就需要克隆数据库到本地。
          # 如果有数据不必克隆数据，直接退出()
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # 如果是master数据也不必克隆
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          [[ $ordinal -eq 0 ]] && exit 0
          # 从序列号比自己小一的数据库克隆数据，比如mysql-2会从mysql-1处克隆数据
          ncat --recv-only mysql-ss-$(($ordinal-1)).mysql-svc-master 3307 | xbstream -x -C /var/lib/mysql
          # 比较数据
          xtrabackup --prepare --target-dir=/var/lib/mysql
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
      containers:
      - name: mysql
        image: mysql:8.0.19
        args: ["--default-authentication-plugin=mysql_native_password"]
        env:
        - name: MYSQL_ALLOW_EMPTY_PASSWORD
          value: "1"
        ports:
        - name: mysql
          containerPort: 3306
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
        resources:
          requests:
            cpu: 250m
            memory: 256Mi
          limits:
            cpu: 500m
            memory: 512Mi
        livenessProbe:
          exec:
            command: ["mysqladmin", "ping"]
          initialDelaySeconds: 30
          periodSeconds: 10
          timeoutSeconds: 5
        readinessProbe:
          exec:
            command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
          initialDelaySeconds: 5
          periodSeconds: 2
          timeoutSeconds: 1
      - name: xtrabackup
        image: mzmuer/xtrabackup:1.0
        ports:
        - name: xtrabackup
          containerPort: 3307
        command:
        - bash
        - "-c"
        - |
          set -ex
          # 确定binlog 克隆数据位置(如果binlog存在的话).
          cd /var/lib/mysql
          # 如果存在该文件，则该xrabackup是从现有的从节点克隆出来的。
          if [[ -s xtrabackup_slave_info ]]; then
            mv xtrabackup_slave_info change_master_to.sql.in
            rm -f xtrabackup_binlog_info
          elif [[ -f xtrabackup_binlog_info ]]; then         
            [[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || 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     
          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"
            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-ss-0.mysql-svc-master',
            MASTER_USER='root',
            MASTER_PASSWORD='',
            MASTER_CONNECT_RETRY=10;
          START SLAVE;
          EOF
          fi
          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
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
          limits: 
            cpu: 200m
            memory: 200Mi
      volumes:
      - name: conf
        emptyDir: {}
      - name: config-map
        configMap:
          name: mysql
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:    
      storageClassName: mysql-sc
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 10Gi

1.initContainers作用：

• 主数据库无需同步自己数据，从数据库需要被同步数据

• 判断当前启动的容器是主还是slave，并向pod的conf卷写入如下数据

  cat /mnt/conf.d/server-id.cnf
  [mysqld]
  server-id=10?
  ls /mnt/conf.d/  
  master[?salve].cnf # 从configmap处拷贝而来

• 当执行完command命令后生命终止，但是pod的conf卷的数据依然存在，因为初始容器和接下来的container容器使用共同的volumes卷,不同的是conf被initContainer挂载到/mnt/conf.d，而在container被挂载在/etc/mysql/conf.d/

  2.Container作用：

• 提供mysql服务

• 运行xtrabakup应用容器提供数据同步

mysql-svc-read 服务

apiVersion: v1
kind: Service
metadata:
  name: mysql-svc-read
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
  selector:
    app: mysql

测试 mysql-svc-read 服务

kubectl run mysql-client-loop --image=mysql:8.0.19 -i -t -n test --rm --restart=Never --\
bash -ic "while sleep 1; do mysql -h mysql-svc-read -e 'SELECT @@server_id,NOW()'; done"

每秒查询一次数据库，可以观察到，调度到不同的 server_id，即 pod 节点

删除部署

kubectl delete statefulset mysql-ss -n test
kubectl delete configmap,service,pvc -l app=mysql -n test

参考资料

按照K8s官方文档部署Mysql高可用+读写分离的坑
【深入分析】K8s部署Mysql主从复制+读写分离
【全网最全最详细】Kubernetes部署Mysql主从复制+读写分离
kubernetes中 mysql集群出现Access denied for user ‘root’@’localhost’ (using password: NO)
Kubernetes-部署高可用的MySQL