概念和理论百度已经介绍得够全面了，这次来说说如何快速配置并生效。

Keepalive 配置

/etc/keepalived/keepalived.conf：

! Configuration File for keepalived

vrrp_script chk_nginx {
    # 检查脚本路径
    script "bash /etc/keepalived/check_nginx.sh"
    interval 2
    weight -5
    fall 3
    rise 2
}

vrrp_instance VI_1 {
    # 设定主从，第二台设置为 BACKUP
    state MASTER
    interface eth0
    # 主机 IP
    mcast_src_ip 10.0.125.156
    virtual_router_id 51
    # 权重，越大优先级越高
    # BACKUP 设置为 99
    priority 100
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        # VIP
        10.0.125.158
    }
    track_script {
       chk_nginx
    }
}

chk_nginx 脚本

/etc/keepalived/check_nginx.sh：

#!/bin/bash
counter=$(ps -C nginx --no-heading|wc -l)
if [ "${counter}" = "0" ]; then
    # 根据自身情况设定
    /usr/local/nginx/sbin/nginx -s start
    sleep 2
    counter=$(ps -C nginx --no-heading|wc -l)
    if [ "${counter}" = "0" ]; then
        /etc/init.d/keepalived stop
    fi
fi

配置完成后重启 keepalived 即可。