apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
  name: mysql
spec:
  serviceName: mysql
  replicas: 3
  template:
    metadata:
      labels:
        app: mysql
      annotations:
        pod.beta.kubernetes.io/init-containers: '[
          {
            "name": "init-mysql",
            "image": "mysql:5.7",
            "command": ["bash", "-c", "
              set -ex\n
              # Generate mysql server-id from pod ordinal index.\n
              [[ `hostname` =~ -([0-9]+)$ ]] || exit 1\n
              ordinal=${BASH_REMATCH[1]}\n
              echo [mysqld] > /mnt/conf.d/server-id.cnf\n
              # Add an offset to avoid reserved server-id=0 value.\n
              echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf\n
              # Copy appropriate conf.d files from config-map to emptyDir.\n
              if [[ $ordinal -eq 0 ]]; then\n
                cp /mnt/config-map/master.cnf /mnt/conf.d/\n
              else\n
                cp /mnt/config-map/slave.cnf /mnt/conf.d/\n
              fi\n
            "],
            "volumeMounts": [
              {"name": "conf", "mountPath": "/mnt/conf.d"},
              {"name": "config-map", "mountPath": "/mnt/config-map"}
            ]
          },
          {
            "name": "clone-mysql",
            "image": "gcr.io/google-samples/xtrabackup:1.0",
            "command": ["bash", "-c", "
              set -ex\n
              # Skip the clone if data already exists.\n
              [[ -d /var/lib/mysql/mysql ]] && exit 0\n
              # Skip the clone on master (ordinal index 0).\n
              [[ `hostname` =~ -([0-9]+)$ ]] || exit 1\n
              ordinal=${BASH_REMATCH[1]}\n
              [[ $ordinal -eq 0 ]] && exit 0\n
              # Clone data from previous peer.\n
              ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql\n
              # Prepare the backup.\n
              xtrabackup --prepare --target-dir=/var/lib/mysql\n
            "],
            "volumeMounts": [
              {"name": "data", "mountPath": "/var/lib/mysql", "subPath": "mysql"},
              {"name": "conf", "mountPath": "/etc/mysql/conf.d"}
            ]
          }
        ]'
    spec:
      containers:
      - name: mysql
        image: mysql:5.7
        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: 1
            memory: 1Gi
        livenessProbe:
          exec:
            command: ["mysqladmin", "ping"]
          initialDelaySeconds: 30
          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
          timeoutSeconds: 1
      - name: xtrabackup
        image: gcr.io/google-samples/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
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
        resources:
          requests:
            cpu: 100m
            memory: 100Mi
      volumes:
      - name: conf
        emptyDir: {}
      - name: config-map
        configMap:
          name: mysql
  volumeClaimTemplates:
  - metadata:
      name: data
      annotations:
        volume.alpha.kubernetes.io/storage-class: default
    spec:
      accessModes: ["ReadWriteOnce"]
      resources:
        requests:
          storage: 10Gi