分步LVS:详解利用Keepalived+Nginx解决站点高可用性

方案&＃xff1a;

利用keepalived&＃43;nginx实现官网web的高可用性

两台服务器一台为主&＃xff0c;一台为备机&＃xff0c;使两台机器公用一个虚拟IP&＃xff0c;当主服务器宕机&＃xff0c;106.3.32.6这个IP会自动切换到备机上&＃xff0c;前端机恢复之后再自动切换回主服务机

然后&＃xff0c;主服务机和备机利用rsync实现实时同步数据&＃xff0c;

rsync的安装配置可以参照我之前的一篇文章&＃xff1a;http://cuimk.blog.51cto.com/6649029/1322241

环境&＃xff1a;

CentOS 6.4

nginx-1.2.1

keepalived-1.2.2

主和辅都需要安装keepalived,安装方法相同

yum -y install  kernel-devel
yum install openssl-* -y
wget http://www.keepalived.org/software/keepalived-1.2.2.tar.gz
tar xzf keepalived-1.2.2.tar.gz
cd keepalived-1.2.2
./configure --prefix&＃61;/usr/local/keepalived
make && make install
ln -s /usr/src/kernels/2.6.18-238.el5-i686/ /usr/src/linux
cp /usr/local/keepalived/etc/rc.d/init.d/keepalived /etc/init.d/
cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
mkdir -pv /etc/keepalived
cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
ln -s /usr/local/keepalived/sbin/keepalived /sbin/

加入开机启动&＃xff1a;chkconfigkeepalived on

主和辅配置的差别只在stateMASTER和priority 100

vi /etc/keepalived/keepalived.conf

! Configuration File for keepalived
global_defs {
#   notification_email {    ####此处定义发生替换会邮件通知
#     cuimingkun&＃64;yinwuweiye.com
#   }
#   notification_email_from keepalived&＃64;domain.com
#   smtp_server 127.0.0.1
#   smtp_connect_timeout 30router_id LVS_DEVEL
}
vrrp_script chk_http_port {script "/root/shell/nginx_pid.sh" ##监控脚本位置interval 2weight 2
}
track_script {chk_http_port}
vrrp_instance VI_1 {state MASTER        #####备机为BACKUPinterface em1virtual_router_id 51priority 100        #####备机要小于主advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {106.3.32.6  ####虚拟IP}
} 三、分别在主和辅服务器上建立nginx的监控脚本

Keepalived管理虚IP是通过组播和优先级实现的&＃xff0c;优先级高的会拥有虚IP的管理权&＃xff0c;所以要实现IP自动切换&＃xff0c;只需要建立一个监控脚本&＃xff0c;让keepalived进行调用&＃xff0c;一旦发现nginx出现故障就kill掉keepalived的进程&＃xff0c;让其他keepalived管理此IP

vi /root/shell/nginx_pid.sh

#!/bin/bash
A&＃61;&＃96;ps -C nginx --no-header |wc -l&＃96;           
if [ $A -eq 0 ];then                                    /usr/local/nginx/sbin/nginxsleep 3if [ &＃96;ps -C nginx --no-header |wc -l&＃96; -eq 0 ];thenkillall keepalivedfi
fi

注意给脚本添加执行权限&＃xff1a;chmod&＃43;x /root/shell/nginx_pid.sh

两台机器启动keepalived&＃xff1a;service keepalived start

#ip a查看IP

查看主的IP&＃xff0c;目前虚IP在主这里

Kill掉主的keepalived,再查看&＃xff0c;虚IP消失

查看辅的这边&＃xff0c;可以看到虚IP

再启动主的keepalived&＃xff0c;虚IP又回到主的这边

此方案没有做负载均衡&＃xff0c;只是做了一个故障自动切换的处理&＃xff0c;适用于PV不是很高的环境&＃xff08;当然Nginx做好调优其负载能力也是很强的&＃xff09;&＃xff0c;不过可以以同样的原理举一反三&＃xff0c;把他做在高并发的负载均衡器上&＃xff0c;来实现高必发的容灾方案&＃xff01;