StatefulSet[实例]-Mysql集群

Introduce

基于StatefulSet搭建K8s集群中的Mysql集群

1. —个‘主从复制”（MaserˉSlaveReplicatjon）的MySQL集群;

2. 有一个主节点（Master）;

3. 有多个从节点（Slave）;

4. 从节点需要能水平扩展;

5. 所有写操作只能在主节点上执行;

6. 读操作可以在所有节点上执行

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How to work

1. 通过XtraBackup实现MySql备份

2. 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;

3. 启动节点备份：

   START SLAVE;

4. 添加节点

Deploy

1. 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

2. 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

3. 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