一、环境说明

VirtualBox6.1
CenOS7
Nginx
keepalived-1.1.20.tar.gz

二、IP配置

主Keepalived服务器IP地址：10.0.2.4
备Keepalived服务器IP地址：10.0.2.5
虚拟Keepalived服务器IP地址：10.0.2.6

三、下载地址

http://www.keepalived.org/software/ 可以选择自己需要的版本。

四、安装步骤

1、下载好安装包，可使用xshell软件连接虚拟机，将压缩包上传至/home目录。或者直接在虚拟机里执行命令下载：wget http://www.keepalived.org/software/keepalived-1.1.20.tar.gz（如果提示没有wget命令，安装即可：yum install wget）。
2、解压keepalived（两个虚拟机都需要做，步骤一致）：

[root@localhost]# cd /home  
[root@localhost home]# tar -zxvf keepalived-1.1.20.tar.gz 
[root@localhost home]# cd keepalived-1.1.20
[root@localhost keepalived-1.1.20]# ln -s /usr/src/kernels/2.6.9-78.EL-i686/usr/src//linux
[root@localhost keepalived-1.1.20]# ./configure

执行完./configure后会显示：

3、编译安装:

[root@localhost keepalived-1.1.20]# make && make install   

4、修改配置文件路径：

[root@localhost keepalived-1.1.20]# cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
[root@localhost keepalived-1.1.20]# cp /usr/local/etc/sysconfig/keepalived /etc/sysconfig/
[root@localhost keepalived-1.1.20]# mkdir /etc/keepalived
[root@localhost keepalived-1.1.20]# cp /usr/local/etc/keepalived/keepalived.conf/etc/keepalived/                  
[root@localhost keepalived-1.1.20]# cp /usr/local/sbin/keepalived /usr/sbin/

5、设置服务开机启动:

[root@localhost keepalived-1.1.20]# vi /etc/rc.local 

在最后一行加上： /etc/init.d/keepalived start

五、配置流程

1、配置 主：

[root@localhost keepalived-1.1.20]# vi /etc/keepalived/keepalived.conf 

2、配置 备：

[root@localhost keepalived-1.1.20]# vi /etc/keepalived/keepalived.conf 

3、启动服务：

六、验证测试

1、创建监控双机nginx状态的脚本：vi /opt/check_nginx.sh
写入以下代码：

#!/bin/sh
A=`ps -C nginx --no-header |wc -l`
if [ $A -eq 0 ];then  #如果nginx没在运行
   systemctl start nginx.service  #启动nginx
   sleep 2
   if [ `ps -C nginx --no-header |wc -l` -eq 0 ];then  #如果无法启动
	killall keepalived  #杀死keepalived进程
   fi
fi

2、安装psmisc，因为脚本用到了killall命令，最小化安装的centos没有，所以要安装一下：yum -y install psmisc。
3、再次编辑keepalived配置文件：

vi /etc/keepalived/keepalived.conf

插入第一段：

vrrp_script check_nginx
{
   script "/root/check_nginx.sh"
   interval 2
   weight 2
}

再插入第二段：

track_script 
{ 
        check_nginx
}

它们的位置如下：

4、备用机与此步骤一样。
5、启动keepalived服务,并开机自启。

systemctl start keepalived.service
systemctl enable keepalived.service

6、测试：
修改一下主机nginx的欢迎界面，以和备用机区分：添加单词Master和Backup：

7、在浏览器输入虚拟机ip：81，停掉主机服务器的nginx，systemctl stop nginx.service。刷新页面会发现没有变化，这是因为keepalived检测到nginx挂了，会通过check_nginx.sh脚本自动启动nginx。

8、当手动停止主机的keepalived：systemctl stop keepalived.service
会发现页面标题的Master没有了，就变成了Backup。

此时才算是配置成功了。