基础架构如下

准备干净的实验环境

[root@mysql1 ~]# systemctl stop firewalld
[root@mysql1 ~]# cat /etc/sysconfig/selinux |grep "SELINUX=disabled"
SELINUX=disabled
[root@mysql1 ~]# setenforce 0              
setenforce: SELinux is disabled
[root@mysql1 ~]# getenforce                
Disabled

首先，搭建221和222机器mysql互为主从

这里可以参考我之前的帖子mysql主从复制
mysql双主双从

我们本次实验只是两台机器互为主从，即互为master和slave

搭建完成后登录mysql 可以查看状态：
mysql1机器：

mysql2：

可以自行验证修改数据，两边数据库是否同步

---

随后
开始安装配置 keepalived (mysql1& mysql2)

mysql1：

[root@mysql1 ~]# yum -y install keepalived
[root@mysql1 ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived

global_defs {
   router_id mysql1
   script_user root
   enable_script_security
   user root
}

vrrp_script check_run {
   script "/etc/keepalived/keepalived_check_mysql.sh"
   interval 5
   weight 2
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33
    virtual_router_id 88
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass yryr
    }

    track_script {
        check_run
    }

    virtual_ipaddress {
        192.168.29.100/24 dev ens33 label ens33:1
    }
}

mysql2：

[root@mysql2 ~]# yum -y install keepalived
[root@mysql2 ~]# vim /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
    router_id mysql2
    script_user root
    enable_script_security
}

vrrp_script check_run {
   script "/etc/keepalived/keepalived_check_mysql.sh"
   interval 5
   weight 2
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33
    virtual_router_id 88
    priority 50
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass yryr
    }

    track_script {
        check_run
    }

    virtual_ipaddress {
        192.168.29.100/24 dev ens33 label ens33:1
    }
}

两台机器上keepalived都配置了一个mysql的检查脚本 ，现在我们来加上：

[root@mysql2 ~]# vim /etc/keepalived/keepalived_check_mysql.sh

#!/bin/bash
MYSQL=/usr/bin/mysql
MYSQL_HOST=localhost 
MYSQL_USER=root 
MYSQL_PASSWORD=123456
CHECK_TIME=3

MYSQL_OK=1

check_mysql_helth (){ 
    echo "Checking MySQL at $(date)" >> /var/log/keepalived_mysql_check.log
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status" >> /var/log/keepalived_mysql_check.log 2>&1
    if [ $? -eq 0 ]; then 
        MYSQL_OK=1
    else 
        MYSQL_OK=0 
    fi 
    return $MYSQL_OK 
}

while [ $CHECK_TIME -ne 0 ]; do 
    check_mysql_helth 
    if [ $MYSQL_OK -eq 1 ]; then 
        exit 0 
    fi
    let CHECK_TIME--
    sleep 1 
done

echo "MySQL health check failed at $(date)" >> /var/log/keepalived_mysql_check.log
/usr/bin/systemctl stop keepalived
exit 1

授权：

[root@mysql1 ~]# chmod +x /etc/keepalived/keepalived_check_mysql.sh

重启服务：

[root@mysql1 local]# systemctl restart keepalived

[root@mysql2 local]# systemctl restart keepalived

查看：
可以看到我们的vip 100 已经飘到 master机器上

[root@mysql1 local]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 00:0c:29:5f:08:ee brd ff:ff:ff:ff:ff:ff
    inet 192.168.29.221/24 brd 192.168.29.255 scope global noprefixroute ens33
       valid_lft forever preferred_lft forever
    inet 192.168.29.100/24 scope global secondary ens33:1
       valid_lft forever preferred_lft forever
    inet6 fe80::b09a:b99e:bc92:62ee/64 scope link tentative noprefixroute dadfailed 
       valid_lft forever preferred_lft forever
    inet6 fe80::9073:a63f:e689:8462/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

后续可以停止mysql 服务来验证vip状态~