nginx + keepalived 双机热备

序

双机热备是指两台机器都在运行，但并非两台机器同时在提供服务。
当提供服务的一台出现故障的时候，另外一台会马上自动接管并且提供服务，且切换的时间非常短。

keepalived的工作原理是VRRP——虚拟路由冗余协议。

测试环境如下：

	ip	vip
master	192.168.174.135	192.168.174.140
backup	192.168.174.137	192.168.174.140

nginx

安装

sudo apt-get install nginx

查找配置文件位置

sudo find / -name nginx.conf

/etc/nginx/nginx.conf

修改配置文件（nginx.conf）

user www-data;

worker_processes ;

pid /run/nginx.pid;

events {

    worker_connections ;

}

http {

    sendfile on;

    tcp_nopush on;

    tcp_nodelay on;

    keepalive_timeout ;

    types_hash_max_size ;

    include /etc/nginx/mime.types;

    default_type application/octet-stream;

    access_log /var/log/nginx/access.log;

    error_log /var/log/nginx/error.log;

    server {

        listen  default_server;

        server_name test;

        charset utf-;

        location / {

        root html;

        index index.html index.htm;

        proxy_set_header X-Real_IP $remote_addr;

        client_max_body_size 100m;

        }

    }

}

文件/usr/share/nginx/html/index.html

在192.168.174.135上加上 <h1>Welcome to nginx! 135 </h1>

在192.168.174.137上加上 <h1>Welcome to nginx! ***137*** </h1>

启动

sudo service nginx start

关闭

sudo service nginx stop

keepalived

安装

下载keepalived-1.2.19.tar.gz

tar –zxvf keepalived-1.2..tar.gz

cd keepalived-1.2.

./configure --prefix=/usr/local/keepalived

make

sudo make install

期间可能出现问题：

!!! OpenSSL is not properly installed on your system. !!!
!!! Can not include OpenSSL headers files. !!!

解决

sudo apt-get install libssl.dev

建立软链接

sudo ln -s /usr/local/keepalived/sbin/keepalived /sbin/

sudo ln -s /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/

sudo ln -s /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/

启动

sudo keepalived -D -f /usr/local/keepalived/etc/keepalived/keepalived.conf

关闭

sudo killall keepalived

配置（keepalived.conf）：

global_defs {

    router_id NODEA

}

vrrp_instance VI_1 {

    state MASTER

    interface eth0        #监测网络接口

    virtual_router_id   #主、备必须一样

    priority           #优先级：主＞备

    advert_int

    authentication {

        auth_type PASS #VRRP认证，主备一致

        auth_pass   #密码

}

virtual_ipaddress {

        192.168.174.140/ #VRRP HA虚拟地址

    }

}

备用节点的配置

global_defs {

   router_id NODEB

}

vrrp_instance VI_1 {

    state BACKUP

    interface eth0

    virtual_router_id

    priority

    advert_int

    authentication {

        auth_type PASS

        auth_pass

    }

 virtual_ipaddress {

    192.168.174.140/

    }

}

测试

双击热备

两台机子均启动nginx和keepalived，浏览器各自访问

浏览器访问：http://192.168.174.140/，显示的是MASTER的页面。

同样用ip appr可以验证：

135机器：

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo