【全网最全最详细】K8s部署Mysql 8主从复制+读写分离

本文使用静态存储卷实现(非存储类)，目的是比较简单易入门。
部署mysql5.7集群的请看这篇文章

软件	版本
mysql	8.0.18
xtrabackup	8.0.9

0、制作xtrabackup镜像(该步可跳过，可直接使用作者现成镜像)
[root@localhost ~]$ vi Dockerfile

FROM paigeeworld/centos7:latest

MAINTAINER jstang <389634070@qq.com>

RUN rpm --rebuilddb && \
    yum -y install wget hostname mariadb && \
    wget https://downloads.percona.com/downloads/Percona-XtraBackup-LATEST/Percona-XtraBackup-8.0.9/binary/redhat/7/x86_64/percona-xtrabackup-80-8.0.9-1.el7.x86_64.rpm && \
	yum -y localinstall percona-xtrabackup-80-8.0.9-1.el7.x86_64.rpm

RUN rm percona-xtrabackup-80-8.0.9-1.el7.x86_64.rpm -rf

EXPOSE 3307

[root@localhost ~]$ docker build -t jstang/xtrabackup:2.3
[root@localhost ~]$ docker login
[root@localhost ~]$ docker push jstang/xtrabackup:2.3
这个是构建镜像和把镜像上传到作者的dockerHub的jstang账户上

1、准备NFS服务,查看NFS服务器IP为192.168.1.11，准备三个持久化磁盘(块)

[root@m-nfs~]# yum install nfs-utils
[root@m-nfs~]# mkdir -p /net/mysql-0 /net/mysql-1 /net/mysql-2
[root@m-nfs~]# ifconfig | head -2| tail -1|awk '{print $2}'
192.168.1.11 # 查看nfs服务器IP
[root@m-nfs~]# echo '/net/mysql-0 *(rw,no_root_squash)' >> /etc/exports
[root@m-nfs~]# echo '/net/mysql-1 *(rw,no_root_squash)' >> /etc/exports
[root@m-nfs~]# echo '/net/mysql-2 *(rw,no_root_squash)' >> /etc/exports
[root@m-nfs~]# systemctl restart nfs-server
[root@m-nfs~]# showmount -e 本机IP # 验证

2、创建三个持久卷(mysql-0、mysql-1、mysql-2)

  apiVersion: v1
  kind: PersistentVolume
  metadata:
    name: pv-a|pv-b|pv-c
  spec:
    capacity:
      storage: 1Gi
    accessModes: 
    - ReadWriteOnce
    - ReadOnlyMany
   #persistentVolumeReclaimPolicy: Retain # 当声明被释放，pv将保留(不清理和删除)
    persistentVolumeReclaimPolicy: Recycle # 当声明被释放，空间将回收再利用
    nfs:
      server: 192.168.1.11
      path: /net/mysql-0 | /net/mysql-1 | /net/mysql-2

3、创建configMap配置字典

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

4、部署headless服务，有状态服务都需要，让服务旗下的Pod彼此发现

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

5. 部署SatefulSet应用

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: mysql-ss
spec: 
  selector: 
    matchLabels: 
      app: mysql 
  serviceName: mysql-headless
  replicas: 1
  template: 
    metadata:
      labels:
        app: mysql 
    spec:
      initContainers:
      - name: init-mysql
        image: mysql:8.0.18
        command:
        - bash
        - "-c"
        - |
          set ex
          # 从hostname中获取索引，比如(mysql-1)会获取(1)
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          echo [mysqld] > /mnt/conf.d/server-id.cnf
          # 为了不让server-id=0而增加偏移量
          echo server-id=$((100 + $ordinal)) >> /mnt/conf.d/server-id.cnf
          # 拷贝对应的文件到/mnt/conf.d/文件夹中
          if [[ $ordinal -eq 0 ]]; then
            cp /mnt/config-map/master.cnf /mnt/conf.d/
          else
            cp /mnt/config-map/slave.cnf /mnt/conf.d/
          fi
        volumeMounts:
        - name: conf
          mountPath: /mnt/conf.d
        - name: config-map
          mountPath: /mnt/config-map
      - name: clone-mysql
        image: jstang/xtrabackup:2.3
        command:
        - bash
        - "-c"
        - |
          set -ex
          # 整体意思:
          # 1.如果是主mysql中的xtrabackup,就不需要克隆自己了,直接退出
          # 2.如果是从mysql中的xtrabackup,先判断是否是第一次创建，因为第二次重启本地就有数据库，无需克隆。若是第一次创建(通过/var/lib/mysql/mysql文件是否存在判断),就需要克隆数据库到本地。
          # 如果有数据不必克隆数据，直接退出()
          [[ -d /var/lib/mysql/mysql ]] && exit 0
          # 如果是master数据也不必克隆
          [[ `hostname` =~ -([0-9]+)$ ]] || exit 1
          ordinal=${BASH_REMATCH[1]}
          [[ $ordinal -eq 0 ]] && exit 0
          # 从序列号比自己小一的数据库克隆数据，比如mysql-2会从mysql-1处克隆数据
          ncat --recv-only mysql-ss-$(($ordinal-1)).mysql-headless 3307 | xbstream -x -C /var/lib/mysql
          # 比较数据
          xtrabackup --prepare --target-dir=/var/lib/mysql
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
      containers:
      - name: mysql
        image: mysql:8.0.18
        args: ["--default-authentication-plugin=mysql_native_password"]
        env:
        - name: MYSQL_ALLOW_EMPTY_PASSWORD
          value: "1"
        ports:
        - name: mysql
          containerPort: 3306
        volumeMounts:
        - name: data
          mountPath: /var/lib/mysql
          subPath: mysql
        - name: conf
          mountPath: /etc/mysql/conf.d
        resources:
          requests:
            cpu: 50m
            memory: 50Mi
        livenessProbe:
          exec:
            command: ["mysqladmin", "ping"]
          initialDelaySeconds: 30
          periodSeconds: 10
          timeoutSeconds: 5
        readinessProbe:
          exec:
            command: ["mysql", "-h", "127.0.0.1", "-e", "SELECT 1"]
          initialDelaySeconds: 5
          periodSeconds: 2
          timeoutSeconds: 1
      - name: xtrabackup
        image: jstang/xtrabackup:2.3
        ports:
        - name: xtrabackup
          containerPort: 3307
        command:
        - bash
        - "-c"
        - |
          set -ex
          # 确定binlog 克隆数据位置(如果binlog存在的话).
          cd /var/lib/mysql
          # 如果存在该文件，则该xrabackup是从现有的从节点克隆出来的。
          if [[ -s xtrabackup_slave_info ]]; then
            mv xtrabackup_slave_info change_master_to.sql.in
            rm -f xtrabackup_binlog_info
          elif [[ -f xtrabackup_binlog_info ]]; then         
            [[ `cat xtrabackup_binlog_info` =~ ^(.*?)[[:space:]]+(.*?)$ ]] || 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-ss-0.mysql-headless',
            MASTER_USER='root',
            MASTER_PASSWORD='',
            MASTER_CONNECT_RETRY=10;
          START SLAVE;
          EOF
          fi
          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: 10m
            memory: 10Mi
      volumes:
      - name: conf
        emptyDir: {
    
    }
      - name: config-map
        configMap:
          name: mysql
  volumeClaimTemplates:
  - metadata:
      name: data
    spec:    
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 0.1Gi

5. 查看状态
5.1 容器运行情况

5.2 主从复制情况

6. 测试
6.1 mysql-0创建数据库

create database ui;
create table ui.user(name varchar(255));
insert into ui.user(name) values("jstang");

5.2 从数据库查数据(查到就成功了。)

select * from ui.user;