主从服务器如何自动切换,Nginx+Keepalive主从 双机热备 + 自动切换解决方案

环境采集cenots 6.3 64位迷你安装，因为安装前，你需要做一些工作

yum install -y make wget

如果你愿意可以更新下系统，更换下yum源.

1.安装keepalive

官方最新版  keepalived-1.2.7

tar zxvf keepalived-1.2.7.tar.gz

cd keepalived-1.2.7

在此之前。请安装一下一些简单的工具

yum install -y gcc openssl-devel popt-devel

不然会编译不成功的。

然后

./configure

make && make install

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

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

chmod +x /etc/init.d/keepalived

chkconfig --add keepalived

chkconfig keepalived on

mkdir /etc/keepalived

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

2.安装nginx

nginx-1.2.5.tar.gz

tar zxvf  nginx-1.2.5.tar.gz

cd nginx-1.2.5

安装一下相关组件.

yum install -y pcre-devel

./configure --prefix=/usr/local/nginx --user=www --group=www  --with-http_stub_status_module --with-http_ssl_module

make && make install

3.配置keepalive

两台服务器端keepalived.conf内容都为如下，都设置为backup，不抢占，注意修改优先级不同,更详细的keepalived配置文件说明可以执行man keepalived.conf查看：

! Configuration File for keepalived

global_defs {

notification_email {

admin@lvtao.net

}

notification_email_from admin@lvtao.net

smtp_server 127.0.0.1

smtp_connect_timeout 30

router_id LVS_DEVEL

}

#监控服务.NGINX mysql等

vrrp_script chk_nginx {

script "/home/check_nginx.sh"

interval 2

weight 2

}

vrrp_instance VI_1 {

state BACKUP  #主从设置 MASTER

interface eth2  #网卡名

virtual_router_id 51

mcast_src_ip 10.0.1.133 #本机IP

priority 50  #从机小于主机

advert_int 1

authentication {

auth_type PASS

auth_pass chtopnet

}

virtual_ipaddress {

10.0.1.2  #VIP 的IP

}

track_script {

chk_nginx  #检测脚本

}

}

virtual_server 10.0.1.2 80 {

delay_loop 6

lb_algo rr

lb_kind DR

persistence_timeout 50

protocol TCP

real_server 10.0.1.132 80 {

weight 3

TCP_CHECK {

connect_timeout 10

nb_get_retry 3

delay_before_retry 3

connect_port 80

}

}

real_server 10.0.1.133 80 {

weight 3

TCP_CHECK {

connect_timeout 10

nb_get_retry 3

delay_before_retry 3

connect_port 80

}

}

}

启动相关服务。我在这儿使用的是nginx ，每个上面开了一个站点，通过IP可以直接访问的。启动keepalive后，就可以通过VIP的虚拟IP 10.0.1.2来访问站点了，测试方法就是 停止任何其中一个站点，看它是否能自动切换到从服务器上。

上面代码中 nginx的检测脚本如下 ：

#!/bin/bash

if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]

then

/usr/local/nginx/sbin/nginx

sleep 5

if [ "$(ps -ef | grep "nginx: master process"| grep -v grep )" == "" ]

then

killall keepalived

fi

fi

在两台Web Server上执行realserver.sh脚本，为lo:0绑定VIP地址10.0.1.2、抑制ARP广播。

#!/bin/bash

#description: Config realserver

VIP=10.0.1.2

/etc/rc.d/init.d/functions

case "$1" in

start)

/sbin/ifconfig lo:0 $VIP netmask 255.255.255.255 broadcast $VIP

/sbin/route add -host $VIP dev lo:0

echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore

echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce

echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore

echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce

sysctl -p >/dev/null 2>&1

echo "RealServer Start OK"

;;

stop)

/sbin/ifconfig lo:0 down

/sbin/route del $VIP >/dev/null 2>&1

echo "0" >/proc/sys/net/ipv4/conf/lo/arp_ignore

echo "0" >/proc/sys/net/ipv4/conf/lo/arp_announce

echo "0" >/proc/sys/net/ipv4/conf/all/arp_ignore

echo "0" >/proc/sys/net/ipv4/conf/all/arp_announce

echo "RealServer Stoped"

;;

*)

echo "Usage: $0 {start|stop}"

exit 1

esac

exit 0

分别在主从机上执行  sh realserver.sh start  就可实现负载均衡及高可用集群了；