1、准备

两台相同配置的web

功能机器	IP
MASTER	192.168.1.92
BACKUP	192.168.1.98

2、安装

两台服务器分别安装Nginx和keepalive

安装依赖包

yum -y install gcc pcre-devel zlib-devel openssl-devel
yum -y install popt-devel

下载

wget http://nginx.org/download/nginx-1.2.4.tar.gz
wget https://www.keepalived.org/software/keepalived-1.2.7.tar.gz

安装nginx、安装keepalive

tar zxvf keepalived-1.2.7.tar.gz
cd keepalived-1.2.7
./configure
make && make install

cp /usr/local/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
cp /usr/local/etc/sysconfig/keepalived  /etc/rc.d/sysconfig/
mkdir /etc/keepalived
cp /usr/local/etc/keepalived/keepalived.conf  /etc/keepalived/
cp /usr/local/sbin/keepalived  /usr/sbin/

启动服务,写入开机启动的脚本里面去

echo  '/usr/local/nginx/sbin/nginx' >> /etc/rc.local
echo  '/etc/init.d/keepalived start' >> /etc/rc.local

3、配置

配置nginx

两台服务器nginx的配置完全一样，主要配置 /usr/local/nginx/conf/nginx.conf 中的http。其中多个域名指向是通过虚拟主机（配置 server）实现，同一域名的不同虚拟目录通过每个server下面的 localtion 实现，在后端服务器 http下面配置 upstream，然后在server或localtion 下面通过 proxypass 引用。
http配置如下

http {
    include mime.types;
    default_type applecation/octet-stream;

    sendfile      on;

    upstream www.ping.cn {
        server  50.1.1.21:80;
    }
    
    upstream dev.jie.cn {
        ip_hash;
        server 192.168.1.100:80;
        server 192.168.1.101:80;
        server 192.168.1.102:80;
    }

    server {
        listen    80;
        server_name    dev.jie.cn;
        location / {
            proxy_pass    http://dev.jie.cn;
        }
    }
}

验证：
先用IP访问各个应用服务器的url
在用域名和路径访问各个应用系统

配置Keepalived

从上面安装的情况，keepalived的配置文件在 /etc/keepalived/keepalived.conf。
主、从服务器的配置相关联但也有不同。如下

Master:
! Configuration File for keepalived

global_defs {
    router_id    NGINX_DEVEL
}

vrrp_instance VI_1 {
    state    MASTER
    interface    eth0
    virtual_router_id 51
    priority 101
    advert_int 1
    
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.92
    }
}

Backup:
! Configuration File for keepalived

global_defs {
    router_id    NGINX_DEVEL
}

vrrp_instance VI_1 {
    state    BACKUP
    interface    eth0
    virtual_router_id 51
    priority 99
    advert_int 1
    
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    virtual_ipaddress {
        192.168.1.92
    }
}

验证：
在主从服务器上都启动 keepalived： /etc/init.d/keepalived start
在主服务器上查看是否已经绑定了虚拟IP：ip addr
停掉主服务器上的keepalived /etc/init.d/keepalived stop
然后在从服务器上看是否已经绑定了虚拟IP
再启动主服务器上的 keepalived, 查看主服务器是否重新结果虚拟IP

让Keepalived监控Nginx的状态