keepalived安装配置

安装keepalived

wget http://www.keepalived.org/software/keepalived-1.2.7.tar.gz

tar zxvf nginx-1.2.7.tar.gz

cd nginx-1.2.7

./configure --with-http_stub_status_module

make && make install

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注意：在执行./configure --with-http_stub_status_module

的时候报错因为少一个库

keepalived执行./configure?--prefix=/usr/local/keepalived时报错：configure: error: Popt libraries is?required
出现此错误的原因：
未安装popt的开发包

解决方法：
yum?install popt-devel
安装好popt的开发包。

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运行环境

cp /usr/local/keepalived/etc/rc.d/init.d/keepalived ?/etc/rc.d/init.d/

cp /usr/local/keepalived/etc/sysconfig/keepalived ?/etc/sysconfig/

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mkdir /etc/keepalived

cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/

cp /usr/local/keepalived/sbin/keepalived /usr/sbin/

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加入启动服务

echo "/etc/init.d/keepalived start" >> /etc/rc.local

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Keepalived 加载的脚本

keepalived -help中

keepalived --use-file?????????? -f??? Use the specified configuration file.

?????????????????????????????? ?Default is /etc/keepalived/keepalived.conf

默认使用的是 /etc/keepalived/keepalived.conf配置文件

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配置keepalived

按照上面的安装方法，keepalived的配置文件在/etc/keepalived/keepalived.conf。主、从服务器的配置相关联但有所不同。如下：

Master:

global_defs {

?? router_id nginx_master

}

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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 {

????? ??50.1.1.2

??? }

}

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Backup:

global_defs {

notification_email {

?? router_id nginx_backup

}

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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 {

?????? ?50.1.1.2

??? }

}

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验证：

??????????????????? 先后在主、从服务器上启动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

??????????????????? 停止主服务器上的keepalived: /etc/init.d/keepalived stop 然后在从服务器上查看是否已经绑定了虚拟IP：

??????????????????? 启动主服务器上的keepalived，看看主服务器能否重新接管虚拟IP

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让keepalived监控NginX的状态

??????????????????? 经过前面的配置，如果主服务器的keepalived停止服务，从服务器会自动接管VIP对外服务；一旦主服务器的keepalived恢复，会重新接管VIP。 但这并不是我们需要的，我们需要的是当NginX停止服务的时候能够自动切换。

??????????????????? keepalived支持配置监控脚本，我们可以通过脚本监控NginX的状态，如果状态不正常则进行一系列的操作，最终仍不能恢复NginX则杀掉keepalived，使得从服务器能够接管服务。

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如何监控NginX的状态

??????????????????? 最简单的做法是监控NginX进程，更靠谱的做法是检查NginX端口，最靠谱的做法是检查多个url能否获取到页面。

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如何尝试恢复服务

??????????????????? 如果发现NginX不正常，重启之。等待3秒再次校验，仍然失败则不再尝试。

根据上述策略很容易写出监控脚本。这里使用nmap检查nginx端口来判断nginx的状态，记得要首先安装nmap。监控脚本如下:

#!/bin/sh

# check nginx server status

NGINX=/usr/local/nginx/sbin/nginx

PORT=80

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nmap localhost -p $PORT | grep "$PORT/tcp open"

#echo $?if [ $? -ne 0 ];then

??? $NGINX -s stop

??? $NGINX

??? sleep 3

??? nmap localhost -p $PORT | grep "$PORT/tcp open"

??? [ $? -ne 0 ] && /etc/init.d/keepalived stopfi

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不要忘了设置脚本的执行权限，否则不起作用。

假设上述脚本放在/opt/chk_nginx.sh，则keepalived.conf中增加如下配置：

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vrrp_script chk_http_port {

??? script "/opt/chk_nginx.sh"

??? interval 2

??? weight 2

}

track_script {

??? chk_http_port

}

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这里又遇到了问题就是脚本怎么都不执行：

最后找到解决办法:

将 track_script ?嵌入到 vrrp_instance 里面

如下：

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global_defs {

?? router_id nginx_master

}

vrrp_script chk_http_port

{

??? script "/opt/chk_nginx.sh"

??? interval 1

? ??weight -2

}

vrrp_instance VI_1 {

??? state MASTER

??? interface eth0

??? virtual_router_id 51

??? priority 101

??? advert_int 1

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??? track_script {

?????? chk_http_port

??? }

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??? authentication {

??????? auth_type PASS

??????? auth_pass 1111

??? }

??? virtual_ipaddress {

??????? 172.16.1.111

??? }

}

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