Nginx+mysql的安装网上多的是，mysql互备等，这里就不写了。

nginx1:192.168.6.155

nginx2:192.168.2.156

最新的1.2.3安装过程有错误 找不到解决方法 就下了个1.2.2的

1.安装配置Keepalived下载所需要的软件
wget http://keepalived.org/software/keepalived-1.2.2.tar.gz
wget http://rpm5.org/files/popt/popt-1.16.tar.gz
 

2.安装popt
编译keepalived时需要popt，否则会报以下错误：configure: error: Popt libraries is required

tar -zxvf popt-1.16.tar.gz
cd popt-1.16
./configure
make
make install

3.安装keepalived

tar -zxvf keepalived-1.2.2.tar.gz
cd keepalived-1.2.2
./configure --prefix=/usr/local/keepalived --with-kernel-dir=/usr/src/kernels/2.6.18-194.8.1.el5-i686/
make
make install

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

4.修改配置文件为以下内容:

vim /usr/local/keepalived/etc/keepalived/keepalived.conf

主站服务器

1. ! Configuration File for keepalived
    
   global_defs {
    router_id LVS_DEVEL
   }
   vrrp_script Monitor_Nginx {
    script "/root/shell/monitor_nginx.sh" #根据自己的实际路径放置monitor_nginx.sh    也可添加多一个check_mysql.sh检测mysql
    interval 2
    weight 2
   }
   vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1
    authentication {
    auth_type PASS
    auth_pass 1234
   }
    track_script {
    Monitor_Nginx
   }
    virtual_ipaddress {
    192.168.6.133
    }
   }

注:备机的keepalived的安装和上面一样，只要把配置文件改为以下(把MASTER改为BACKUP)

! Configuration File for keepalived
 
global_defs {
 router_id LVS_DEVEL
}
vrrp_script Monitor_Nginx {
 script "/root/scripts/monitor_nginx.sh"
 interval 2
 weight 2
}
vrrp_instance VI_1 {
 state BACKUP            #改为BACKUP
 interface eth0
 virtual_router_id 51
 priority 30            #比MASTER数值要低
 advert_int 1
 authentication {
 auth_type PASS
 auth_pass 1234
}
 track_script {
 Monitor_Nginx
}
 virtual_ipaddress {
 192.168.6.133
 }
}

注：monitor_nginx.sh为监控nginx进程的脚本,内容如下

#!/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

mysql状态检测脚本/root/shell/keepalived_check_mysql.sh

vim  /root/shell/keepalived_check_mysql.sh
 

#!/bin/bash
MYSQL=/usr/local/mysql/bin/mysql
MYSQL_HOST=localhost
MYSQL_USER=root
MYSQL_PASSWORD=9ai9.net
CHECK_TIME=3
#mysql  is working MYSQL_OK is 1 , mysql down MYSQL_OK is 0
MYSQL_OK=1
function check_mysql_helth (){
    $MYSQL -h $MYSQL_HOST -u $MYSQL_USER -p${MYSQL_PASSWORD} -e "show status;" >/dev/null 2>&1
    if [ $? = 0 ] ;then
    MYSQL_OK=1
    else
    MYSQL_OK=0
    fi
    return $MYSQL_OK
}
while [ $CHECK_TIME -ne 0 ]
do
    let "CHECK_TIME -= 1"
   
    check_mysql_helth
if [ $MYSQL_OK = 1 ] ; then
    CHECK_TIME=0
    exit 0
fi
if [ $MYSQL_OK -eq 0 ] &&  [ $CHECK_TIME -eq 0 ]
then
    /etc/init.d/keepalived stop
    exit 1
fi
sleep 1
done

赋予执行权限

chmod 755 /root/shell/keepalived_check_mysql.sh

monitor_nginx.sh也一样需要赋予执行权限

5.启动keepalived

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

或者用service keepalived start来启动 service keepalived status来查看状态
用这种 /etc/rc.d/init.d/keepalived start方式来启动有问题 不知道为什么

测试步骤

1．    访问VIP看是否能够正常访问后端的tomcat
2．    停止其中一个tomcat看是否能将访问转到另一台上
3．    停止两台nginx上任何一个nginx进程看监控进程脚本是否会自动启动nginx
4．    停止任何一台nginx上的keepalived进程看另一台是否接管vip
比如停止Master上的keepalived,例如如下killall keepalived,查看BACKUP机器是否已经接管，如果BACKUP接管后，BACKUP机器日志会是出下情况
  eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 00:0c:29:03:9f:88 brd ff:ff:ff:ff:ff:ff
    inet 192.168.6.155/24 brd 192.168.6.255 scope global eth0
    inet 192.168.6.133/32 scope global eth0
    inet6 fe80::20c:29ff:fe03:9f88/64 scope link
       valid_lft forever preferred_lft forever
 

注意：

vrrp协议 使用224.0.0.18地址组播 需要添加到防火墙 以为centos为例：

 -A RH-Firewall-1-INPUT -d 224.0.0.18 -j ACCEPT