认识Keepalived
Keepalived的作用是检测web服务器的状态，如果有一台web服务器死机，或工作出现故障，Keepalived将检测到，并将有故障的web服务器从系统中剔除，当web服务器工作正常后Keepalived自动将web服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的web服务器。
Keepalived实现服务的高可用（HA），应用已经非常广泛，很多软件都会和他搭配使，比如LVS，Nginx，Redis等等。今天先来看看Linux环境中Keepalived是如何安装配置的。
去Keepalived官网（www.keepalived.org）下载软件包，上传至服务器。
开始安装
解压：
[root@localhost ~]# cd /usr/local/software/
[root@localhost software]# tar -zxvf keepalived-1.2.19.tar.gz安装依赖插件：
yum install -y gcc openssl-devel popt-devel编译安装：
[root@localhost software]# cd keepalived-1.2.19
[root@localhost keepalived-1.2.19]# ./configure --prefix=/usr/local/keepalived
[root@localhost keepalived-1.2.19]#make && make install 编译之后的配置
1. 建立服务启动脚本，以便使用service命令控制
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/keepalived
//获取权限
chmod +x /etc/init.d/keepalived
2. 因为我们使用非默认路径（/usr/local）安装的keepalived, 故需要修改几处路径，以保证keepalived能正常启动, 需要修改的文件如下：
修改/etc/init.d/keepalived, 寻找大约15行左右的. /etc/sysconfig/keepalived, 修改为： . /usr/local/keepalived/etc/sysconfig/keepalived, 即指向正确的配置文件位置。
3. 配置环境变量（将keepavlied主程序所在路径导入到环境变量PATH中）：
KEEPALIVED_HOME=/usr/local/keepalived
PATH=$KEEPALIVED_HOME/sbin:$PATH
export PATH
4. 建立可执行文件链接：
ln -s /usr/local/keepalived/sbin/keepalived /usr/sbin/
5. 修改/usr/local/keepalived/etc/sysconfig/keepalived文件，设置正确的服务启动参数
KEEPALIVED_OPTIONS="-D -f /usr/local/keepalived/etc/keepalived/keepalived.conf"
6. 经过以上修改，keepalived基本安全配置即可完成，启动测试之：
service keepalived restart
7. 将Keepalived服务设置为开机启动
chkconfig keepalived on
启动keepalived
[root@localhost keepalived]# service keepalived start
Starting keepalived (via systemctl): [ 确定 ]
[root@localhost keepalived]# 至此Keepalived的安装配置已经完成，后续会介绍Keepalived如何实现HA。