一、拓扑环境：

主nginx负载均衡器 192.168.166.203
辅nginx负载均衡器 192.168.166.177
VIP地址 192.168.166.178 http://www.keepalived.org/download.html
tar -zxvf keepalived-1.2.1.tar.gz
cd keepalived-1.2.1
./configure --prefix=/usr/local/keepalived --sysconf=/etc make && make install
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
cp /usr/local/keepalived/sbin/keepalived /bin/
chkconfig --add keepalived
chmod 755 /etc/init.d/keepalived
chkconfig keepalived on
service keepalived start 二．修改配置文件为以下内容:　[master slave]
MASTER
vim /etc/keepalived/keepalived.conf ! Configuration File for keepalived global_defs { notification_email {
xxx@xxx.com
} notification_email_from xxx@xxx.com
smtp_server xxx.smtp.com
smtp_connect_timeout 30
router_id LVS_DEVEL
} vrrp_script Monitor_Nginx {
script "/root/monitor_nginx.sh"
interval 2
weight 2
} vrrp_instance VI_1 {
state MASTER #(主机为MASTER，备用机为BACKUP)
interface eth0 #(HA监测网络接口)
virtual_router_id 61 #(主、备机的virtual_router_id必须相同)
#mcast_src_ip 192.168.166.203 #(多播的源IP，设置为本机外网IP，与VIP同一网卡)此项可不设置
priority 90 #(主、备机取不同的优先级，主机值较大，备份机值较小,值越大优先级越高)
advert_int 1 #(VRRP Multicast广播周期秒数)
authentication {
auth_type PASS #(VRRP认证方式)
auth_pass 1234 #(密码)
}
track_script {
Monitor_Nginx #(调用nginx进程检测脚本)
}
virtual_ipaddress {
192.168.166.178 #(VRRP HA虚拟地址)
}
}
###BACKUP方面只需要修改state为BACKUP , priority比MASTER稍低就OK了 三：注：monitor_nginx.sh为监控nginx进程的脚本,内容如下 #!/bin/bash
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then
/usr/local/nginx/sbin/nginx
sleep 5
if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]
then
killall keepalived
fi
fi #chmod +x monitor_nginx.sh 四.启动keepalived
service keepalived start
或
/usr/local/keepalived/sbin/keepalived -D -f /etc/keepalived/keepalived.conf 五．测试步骤 1． 访问VIP看是否能够正常访问后端的web
2． 停止其中一个web看是否能将访问转到另一台上
3． 停止两台nginx上任何一个nginx进程看监控进程脚本是否会自动启动nginx
4． 停止任何一台nginx上的keepalived进程看另一台是否接管vip
track_interface的意思是将Linux中你想监控的网络接口卡监控起来，当其中的一块出现故障是keepalived都将视为路由器出现故障。
这里请注意： virtual_router_id 61，同一组master/backup中，也就是如果你设置了多个VRRP，同一组这个ID必须相同，不然启动的时候主从都会把VIP给启动了 keepalived 通过发送和接收组播包中的同一个virtual_router_id 的中的成员的存活，来确定对方的不可用，一旦检测到对方的不可用，即会切换它的备份角色为主。
即：当真实机192.168.166.177上的keepalived 检测到 真实机192.168.166.203上的keepalived 不可用时，177上将使用vip:192.168.166.178对外服务并由backup角色转变为master