在三台MySQL服务器下使用Keepalived实现VIP高可用的方案

vrrp_script chk_mysql {
    script "/etc/keepalived/check_mysql.sh"
    interval 2
    weight -20
}
vrrp_instance VI_1 {
    state BACKUP               # 所有节点都用 BACKUP
    nopreempt                  # 关闭抢占
    interface eth0
    virtual_router_id 51
    priority 100               # 最高，初始为主
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.100.100/24
    }
    track_script {
        chk_mysql
    }
}

vrrp_script chk_mysql {
    script "/etc/keepalived/check_mysql.sh"
    interval 2
    weight -20
}
vrrp_instance VI_1 {
    state BACKUP
    nopreempt
    interface eth0
    virtual_router_id 51
    priority 90
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.100.100/24
    }
    track_script {
        chk_mysql
    }
}

vrrp_script chk_mysql {
    script "/etc/keepalived/check_mysql.sh"
    interval 2
    weight -20
}
vrrp_instance VI_1 {
    state BACKUP
    nopreempt
    interface eth0
    virtual_router_id 51
    priority 80
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.100.100/24
    }
    track_script {
        chk_mysql
    }
}

#!/bin/bash
#检查本机 MySQL 是否可写（即当前不是只读的备库）
mysql -u root -p'你的密码' -e "SELECT 1;" &>/dev/null
if [ $? -ne 0 ]; then
    exit 1   # 连接失败，释放 VIP
fi
检查 read_only 是否为 OFF（主库才可写）
READ_ONLY=$(mysql -u root -p'你的密码' -e "SHOW VARIABLES LIKE 'read_only';" | grep -c "OFF")
if [ $READ_ONLY -eq 1 ]; then
    exit 0   # 是主库，可以持有 VIP
else
    exit 1   # 是只读备库，释放 VIP
fi

chmod +x /etc/keepalived/check_mysql.sh

track_script {
    chk_mysql
}

vrrp_script chk_mysql {
    script "/etc/keepalived/check_mysql.sh"
    interval 2          # 每 2 秒检查一次
    weight -20          # 失败时降低优先级 20，确保 VIP 被其他节点接管
}

ip addr show eth0 | grep 192.168.100.100
应看到 VIP。