apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  serviceName: mysql
  replicas: 3
  template:
    metadata:
      labels:
        app: mysql
    spec:
      initContainers:
        - name: init-mysql
          image: mysql:5.7
          command:
            - bash
            - "-c"
            - |
              set -ex
              [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
              ordinal=${BASH_REMATCH[1]}
              echo [mysqld] > /mnt/conf.d/server-id.cnf
              echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
              if [[ $ordinal -eq 0 ]]; then 
                cp /mnt/config-map/master.cnf /mnt/conf.d/ 
              else
                cp /mnt/config-map/slave.cnf /mnt/conf.d/ 
              fi
          volumeMounts:
            - name: conf
              mountPath: /mnt/conf.d
            - name: config-map
              mountPath: /mnt/config-map
        - name: clone-mysql
          image: gcr.io/google-samples/xtrabackup:1.0
          command:
            - bash
            - "-c"
            - |
              set -ex
              [[ -d /var/lib/mysql/mysql ]] && exit 0
              [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
              ordinal=${BASH_REMATCH[1]}
              [[ $ordinal -eq 0 ]] && exit 0
              ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
              xtrabackup --prepare --target-dir=/var/lib/mysql
          volumeMounts:
            - name: data
              mountPath: /var/lib/mysql
              subPath: mysql
            - name: conf
              mountPath: /etc/mysql/conf.d
      containers:
        - name: xtrabackup
          image: gcr.io/google-samples/xtrabackup:1.0
          ports:
            - name: xtrabackup
              containerPort: 3307
          command:
            - bash
            - "-c"
            - |
              set -ex
              cd /var/lib/mysql
              if [[ -f xtrabackup_slave_info ]]; then
                mv xtrabackup_slave_info change_master_to.sql.in
                rm -f xtrabackup_binlog_info
              elif [[ -f xtrabackup_binlog_info ]]; then
                [[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || 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-0.mysql',
                MASTER_USER='root',
                MASTER_PASSWORD='',
                MASTER_CONNECT_RETRY=10;
              START SLAVE;
              EOF
              fi

              # 使用ncat监听3307端口。它的作用是，在收到传输请求的时候，直接执行"xtrabackup --backup"命令，备份MySQL的数据并发送给请求者
              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

        - name: mysql
          image: mysql
          ports:
            - containerPort: 80
              name: web
          volumeMounts:
            - name: www
              mountPath: /usr/share/nginx/html
      volumes:
        - name: conf
          emptyDir: {}
        - name: config-map
          configMap:
            name: mysql
  volumeClaimTemplates:
    - metadata:
        name: data
      spec:
        accessModes: ["ReadWriteOnce"]
        resources:
          requests:
            storage: 2Gi
