一、安装

主和辅都需要安装keepalived,安装方法相同

yum -y install  kernel-devel
yum install openssl-* -y
wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
tar xzf keepalived-1.2.2.tar.gz
cd keepalived-1.2.2
./configure --prefix=/usr/local/keepalived
make && make install
ln -s /usr/src/kernels/2.6.18-238.el5-i686/ /usr/src/linux
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir -pv /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/

加入开机启动：chkconfigkeepalived on

二、配置

主和辅配置的差别只在stateMASTER和priority 100

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
#   notification_email {    ####此处定义发生替换会邮件通知
#     cuimingkun@yinwuweiye.com
#   }
#   notification_email_from keepalived@domain.com
#   smtp_server 127.0.0.1
#   smtp_connect_timeout 30
   router_id LVS_DEVEL
}
vrrp_script chk_http_port {
                script "/root/shell/nginx_pid.sh" ##监控脚本位置
                interval 2
                weight 2
}
track_script {
       chk_http_port
       }
vrrp_instance VI_1 {
    state MASTER        #####备机为BACKUP
    interface em1
    virtual_router_id 51
    priority 100        #####备机要小于主
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        106.3.32.6  ####虚拟IP
    }
}

三、分别在主和辅服务器上建立nginx的监控脚本

Keepalived管理虚IP是通过组播和优先级实现的，优先级高的会拥有虚IP的管理权，所以要实现IP自动切换，只需要建立一个监控脚本，让keepalived进行调用，一旦发现nginx出现故障就kill掉keepalived的进程，让其他keepalived管理此IP

vi /root/shell/nginx_pid.sh

#!/bin/bash
A=`ps -C nginx --no-header |wc -l`           
if [ $A -eq 0 ];then                                    
                /usr/local/nginx/sbin/nginx
                sleep 3
                if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then
                       killall keepalived
                fi
fi

注意给脚本添加执行权限：chmod+x /root/shell/nginx_pid.sh

两台机器启动keepalived：service keepalived start