假设使用场景如下

host1：192.168.0.151
host2：192.168.0.231
虚拟ip：192.168.0.222

一、在线安装keepalived中间件

sudo yum install -y keepalived

二、配置 keepalived

host1 上 keepalived 配置
$ vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 101
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.0.222
    }
}

host2 上 keepalived 配置
$ vim /etc/keepalived/keepalived.conf
vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.0.222
    }
}

注：eth0是网卡，可以通过ifconfig命令进行查看；priority 是用来标记主从服务器的，值大的为主；virtual_ipaddress表示虚拟ip的地址

三 、启动 keepalived 服务

systemctl start keepalived.service
systemctl enable keepalived.service

or

service keepalived start