StatefulSet[实例]-Mysql集群

Introduce

基于StatefulSet搭建K8s集群中的Mysql集群

—个‘主从复制”（MaserˉSlaveReplicatjon）的MySQL集群;
有一个主节点（Master）;
有多个从节点（Slave）;
从节点需要能水平扩展;
所有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

How to work

通过XtraBackup实现MySql备份

配置从节点，复制到/var/lib/mysql，执行

CHANGE MASTER TO
MASTER_HOST='$masterip';
MASTER_USER='xxx';
MATSER_PASSWORK='xxx';
# 这个文件来资源第一个创建的xtrabackup_binlog_info
MASTER_LOG_FILE='TheMaster-bin.00001';
MASTER_LOG_POS=481;

启动节点备份：
1
START SLAVE;
添加节点

Deploy

ConfigMap-MySql

apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql
  labels:
    app: mysql
data:
  master-conf: |
    # 主节点配置文件
    [mysqld]
    log-bin
  slave.conf: |
    # 从节点配置文件
    super-read-only

svc

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

StatefulSet

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql-statefulset
spec:
  selector:
    matchLabels:
      app: mysql # 必须匹配 .spec.template.metadata.labels
  serviceName: "mysql-headless"
  replicas: 1 # 默认值是 1
  minReadySeconds: 10 # 默认值是 0
  template:
    metadata:
      labels:
        app: mysql # 必须匹配 .spec.selector.matchLabels
    spec:
      terminationGracePeriodSeconds: 10
      initContainers:
      - name: init-mysql
        image: mysql:8.0.
        command:
        - bash
        - "-c"
        - |
          set -ex
          # 从Pod的序号生成server-id
          [[ `hostname` =~ -([0-9]+) $ ]] exit ]
          ordinal=${BASH_REMATCH[1]}
          echo [mysqld] > /mnt/conf.d/server-id.cnf
          ＃由于server-1d＝0有特殊含义, 因此给ID加一个100避开它
          echo server-id=$(100+$ordinal)) >> /mnt/conf.d/server-id.crd
          
          if [[ $ordinal -eq 0 ]] ; then
            cp /mnt/config-map/master.conf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.conf /mnt/conf.d/
          fi
          volumeMounts:
          - name: conf
          mountPath: /mnt/conf.d
          - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: grc.io/google-samples/xtrabackup:1.0
        command:
          - bash
          - "-c"
          - |
           set -ex
           # 复制操作只要在第一次启动运行，数据存在就pass
           [ [ -d /var/lib/mysql/mysql ] ] && exit 0
           # 主节点（序号为0）不需要进行该操作
           [[ `hostname` =~ -([0-9+)$ ]] && exit 1
           ordinal=${BASH_REMATCH[1]}
           # 使用nact 远程从一个节点复制数据到本地
           nact --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
           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: xtrabackup
          image: grc.io/google-samples/xtrabackup:1.0
          ports:
            - name: xtrabackup
              containerPort: 3007
          command:
            - bash
            - "-c"
            - |
              set -ex 
              cd /var/lib/mysql
              
              # 从备份文件里面读取MASTER_LOG_FILEM 和 MASTER_LOG_POS 这俩个字段的值
              if [[ -f xtrabackup_slave_info ]] ; then
               # 如果xtrabackup_slave_info 存在，说明备份数据来自另外一个节点
              mv  xtrabackup_slave_info change change_master_to.sql.in
              rm -f xtrabackup_slave_info
              elifi [[ -f xtrabackup_binlog_info ]]; then
              # 如果只存在 xtrabackup_binlog_info 文件，说明备份来自主节点
              [[ `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
              
              # 如果change_master_to.sql.in 存在吗，进行集群初始化
              if [[ -f change_master_to.sql.in ]];then
              echo "Waiting ofr 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"
              # 把change_master_to.sql.in文件重命名，防止重复初始化
              mv change_master_to.sql.in change_master_to.sql.in.orig
              mysql -h 127.0.0.1 <<EOF
              $(<change_master_to.sql.in.orig),
                MASTER_HOST='myslq-0.mysql'
                MASTER_USER='root',
                MASTER_PASSWORD='',
                MASTER_CONNECT_RETRY=10;
              START SLAVE;
              EOF
              fi
              
              # ncat 监听3307，收到传输请求执行 xtrabackup --backup
              exec ncat --listen --keep-one --send-only --max-conns=1 3308 -c \
                " xtrabackup --backup --slave-info --stream=xbstream --host=127.0.0.1 --user=root "
          volumeMounts:
            - mountPath: /var/lib/mysql
              name: data
              subPath: mysql
            - mountPath: conf
              name: conf
              subPath: /etc/mysql/conf.d
        - name: mysql
          image: mysql:8.0.26
          env:
            - name: MYSQL_ALLOW_EMPTY_PASSWORD
              value: "1"
            - name: MYSQL_ROOT_PASSWORD
              value: root
            - name: MYSQL_USER_HOST
              value: '%'
            - name: MYSQL_ROOT_HOST
              value: '%'
            - name: MYSQL_PORT
              value: "3306"
            - name: TZ
              value: Asia/Shanghai
            - name: LANG
              value: en_US.UTF-8
          ports:
            - containerPort: 3306
              name: mysql
          volumeMounts:
            - mountPath: /var/lib/mysql
              name: data
            - mountPath: /etc/mysql/conf.d
              name: conf
          resources:
            requests:
              cpu: 500m
              memory: 1Gi
          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
      volumes:
        - name: conf
          emptyDir: { }
        - name: config-map
          configMap:
            name: mysql