kubernetes安裝MySql 5.7主從複製集羣

一、部署原理

使用 statefulset控制器部署mysql主從集羣的原理如下圖所示：

官方地址： Run a Replicated Stateful

參考博客：CSDN博客

二、使用 statefulset控制器部署mysql主從集羣

2.1、首先從資源清單創建ConfigMap

[root@master-dev mysql_cluster]# cat mysql-configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: mysql
  labels:
    app: mysql
data:
  master.cnf: |
    # Apply this config only on the master.
    [mysqld]
    log-bin
  slave.cnf: |
    # Apply this config only on slaves.
    [mysqld]
    super-read-only

2.2、創建Service，提供服務的訪問和負載均衡

# Headless service for stable DNS entries of StatefulSet members.
apiVersion: v1
kind: Service
metadata:
  name: mysql
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
  clusterIP: None
  selector:
    app: mysql
---
# Client service for connecting to any MySQL instance for reads.
# For writes, you must instead connect to the master: mysql-0.mysql.
apiVersion: v1
kind: Service
metadata:
  name: mysql-read
  labels:
    app: mysql
spec:
  ports:
  - name: mysql
    port: 3306
  selector:
    app: mysql
    

[root@master-dev mysql_cluster]# kubectl apply -f mysql-services.yaml
service/mysql created
service/mysql-read created
[root@master-dev mysql_cluster]# kubectl get svc | grep mysql
mysql                        ClusterIP      None             <none>        3306/TCP          1s
mysql-read                   ClusterIP      10.111.232.160   <none>        3306/TCP          1s

2.3、部署statefulset控制器創建Pod

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
          # Generate mysql server-id from pod ordinal index.
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          echo [mysqld] > /mnt/conf.d/server-id.cnf
          # Add an offset to avoid reserved server-id=0 value.
          echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
          # Copy appropriate conf.d files from config-map to emptyDir.
          if [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: gcr.io/google-samples/xtrabackup:1.0
        command:
        - bash
        - "-c"
        - |
          set -ex
          # Skip the clone if data already exists.
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # Skip the clone on master (ordinal index 0).
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          [[ $ordinal -eq 0 ]] && exit 0
          # Clone data from previous peer.
          ncat --recv-only mysql-$(($ordinal-1)).mysql 3307 | xbstream -x -C /var/lib/mysql
          # Prepare the backup.
          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: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: 500m
            memory: 1Gi
        livenessProbe:
          exec:
            command: ["mysqladmin", "ping"]
          initialDelaySeconds: 30
          periodSeconds: 10
          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
          periodSeconds: 2
          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 && "x$(<xtrabackup_slave_info)" != "x" ]]; then
            # XtraBackup already generated a partial "CHANGE MASTER TO" query
            # because we're cloning from an existing slave. (Need to remove the tailing semicolon!)
            cat xtrabackup_slave_info | sed -E 's/;$//g' > change_master_to.sql.in
            # Ignore xtrabackup_binlog_info in this case (it's useless).
            rm -f xtrabackup_slave_info 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 -f xtrabackup_binlog_info xtrabackup_slave_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"
            mysql -h 127.0.0.1 \
                  -e "$(<change_master_to.sql.in), \
                          MASTER_HOST='mysql-0.mysql', \
                          MASTER_USER='root', \
                          MASTER_PASSWORD='', \
                          MASTER_CONNECT_RETRY=10; \
                        START SLAVE;" || exit 1
            # In case of container restart, attempt this at-most-once.
            mv change_master_to.sql.in change_master_to.sql.orig
          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
    spec:
      accessModes: ["ReadWriteOnce"]
      storageClassName: "nfs-client"    #!!!這裏需要提前創建好storageClass，或者對應的PVC
      resources:
        requests:
          storage: 10Gi

kubectl apply -f https://k8s.io/examples/application/mysql/mysql-statefulset.yaml

kubectl get pods -l app=mysql --watch
NAME      READY     STATUS    RESTARTS   AGE
mysql-0   2/2       Running   0          2m
mysql-1   2/2       Running   0          1m
mysql-2   2/2       Running   0          1m

如若沒有storageClass，需要創建一下pv和pvc

kubectl apply -f cat data_pv.yaml

apiVersion: v1
kind: PersistentVolume
metadata:
  name: data
  labels:
    release: "stable"
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  storageClassName: mynfs
  persistentVolumeReclaimPolicy: Recycle
  nfs:
    path: "/eastorage"
    server: 10.19.86.144
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: data1
  labels:
    release: "stable"
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  storageClassName: mynfs1
  persistentVolumeReclaimPolicy: Recycle
  nfs:
    path: "/emptydir"
    server: 10.19.86.144
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: data2
  labels:
    release: "stable"
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  storageClassName: mynfs2
  persistentVolumeReclaimPolicy: Recycle
  nfs:
    path: "/docker"
    server: 10.19.86.144

kubectl apply -f cat data_pvc.yaml

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: data-mysql-0
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: mynfs
  selector:
    matchLabels:
      release: "stable"
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: data-mysql-1
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: mynfs1
  selector:
    matchLabels:
      release: "stable"
---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: data-mysql-2
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: mynfs2
  selector:
    matchLabels:
      release: "stable"

三、主從測試

可以通過運行帶有 mysql:5.7 鏡像的臨時容器並運行 mysql 客戶端二進制文件，將測試查詢發送到 MySQL 主服務器(主機名 mysql-0.mysql )

[root@master-dev mysql]# kubectl run test --image=mysql:5.7 -it -- bash

root@test:/# mysql -h mysql-0.mysql

mysql> create database redhat;
Query OK, 1 row affected (0.11 sec)

mysql> show databases;
+------------------------+
| Database               |
+------------------------+
| information_schema     |
| mysql                  |
| performance_schema     |
| redhat                 |
| sys                    |
| xtrabackup_backupfiles |
+------------------------+
6 rows in set (0.04 sec)

通過訪問mysql-read來查看創建的數據庫是否在從庫創建：

[root@master-dev mysql_cluster]# kubectl get svc | grep mysql
mysql                        ClusterIP      None             <none>        3306/TCP          11m
mysql-read                   ClusterIP      10.111.232.160   <none>        3306/TCP          11m

[root@master-dev mysql]# kubectl attach test -it

root@test:/# mysql -h 10.111.232.160

mysql> show databases;
+------------------------+
| Database               |
+------------------------+
| information_schema     |
| mysql                  |
| performance_schema     |
| redhat                 |
| sys                    |
| xtrabackup_backupfiles |
+------------------------+
6 rows in set (0.05 sec)

可以看出從庫複製了主庫的操作,也可以直接訪問從庫進行驗證，本文記錄的重點就是在部署statefulset時處理存儲問題，需要提前準備好nfs服務，或者有動態的storageClass，否則會處於pengding狀態。