Nginx之keepalived高可用工具
1、创建两台虚拟机，分别为主机和从机，区别两台虚拟机的IP地址
2、 将keepalived上传到linux系统当中
3、 cd /usr/local目录
4、 tar -zxvf keepalived-1.2.18.tar.gz
5、 cd keepalived-1.2.18目录
6、 yum install -y openssl openssl-devel (需要安装一个软件包)
7、 ./configure –prefix=/usr/local/keepalived 编译，将编译文件放到/usr/local/keepalived
8、 make
9、 make install
10、 在/etc/keepalived 创建目录： mkdir /etc/keepalived
11、 cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
12、 cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
13、 cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
14、 ln -s /usr/local/sbin/keepalived /usr/sbin/
（ln -s /usr/local/keepalived/sbin/keepalived /sbin/）
15、 将nginx启动脚本和keepalived.conf配置上传到/etc/keepalived
16、 主机：修改keepalived.conf配置文件 vim /etc/keepalived/keepalived.conf
interface 配置成与主机相同的网络 ip a
mcast_src_ip 配置成自己机器的IP
virtual_ipaddress {
192.168.33.135 # 虚拟ip,也就是解决写死程序的ip怎么能切换的ip,也可扩展，用途广泛。可配置多个。
}
17、 启动keepalived 启动命令service keepalived start
如果报错：Job for keepalived.service failed because the control process exited with error code. See “systemctl status keepalived.service” and “journalctl -xe” for details.
18、解决办法：rm /usr/sbin/keepalived
19、ln -s /usr/local/keepalived/sbin/keepalived /usr/sbin/
20、再次启动
21、可以设置开机启动：chkconfig keepalived on
22、自动重启不了，解决办法
23、备机安装步骤同上，备机修改配置文件步骤如下
24、备机：修改keepalived.conf配置文件 vim /etc/keepalived/keepalived.conf
state BACKUP 备机名称
interface 配置成与主机相同的网络 ip a
mcast_src_ip 配置成自己机器的IP
priority 90 权重配置
virtual_ipaddress {
192.168.33.135 # 虚拟ip,也就是解决写死程序的ip怎么能切换的ip,也可扩展，用途广泛。可配置多个。
}
25、从机启动步骤同上
26、效果展示 访问虚拟IP地址192.168.33.135
27、模拟主机挂掉，高可用工具Keepalived实现自动启动备机，防止宕机
注意：为确保区分主机与备机，在此修改了静态资源HTML的标题
①、挂掉主机
②、虚拟IP地址192.168.33.135继续访问备机
③、 虚拟IP访问效果
④、恢复主机
⑤、虚拟IP地址192.168.33.135继续访问主机
⑥、虚拟IP访问效果
29、keepalived 常用命令
启动Keepalived：service keepalived start
30、注意事项
区分主机与备机名称、
区分主机与备机IP地址、
区分主机与备机的权重 主机权重>备机权重