前提：后端两个RS已经安装好了httpd，并且可以被正常访问到
规划：
Director1：
eth0,DIP:202.207.178.6
eth0:0,VIP:202.207.178.4
Director2：
eth0,DIP:202.207.178.7
eth0:0,VIP:202.207.178.4
RS1:
eth0,RIP:202.207.178.8
lo:0,VIP:202.207.178.4
RS2:
eth0,RIP:202.207.178.9
lo:0,VIP:202.207.178.4
一、配置DR模型（注意：RS1和RS2上的网卡别名地址必须在配置好arp_ignore和arp_announce之后才可配置，为避免影响，应关闭防火墙和SELinux）
1、按上述IP地址规划在相应的网卡上配置相应的IP地址
2、配置RS1和RS2对arp的请求响应，以及其对应VIP
RS1：
# sysctl -w net.ipv4.conf.eth0.arp_announce=2
# sysctl -w net.ipv4.conf.all.arp_announce=2
# echo 1 > /proc/sys/net/ipv4/conf/eth0/arp_ignore
# echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
#ifconfig lo:0 202.207.178.4 broadcast 202.207.178.4 netmask
255.255.255.255
RS2：
# echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
# echo 2 > /proc/sys/net/ipv4/conf/eth0/arp_announce
# echo 1 > /proc/sys/net/ipv4/conf/eth0/arp_ignore
# echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
# ifconfig lo:0 202.207.178.4 broadcast 202.207.178.4 netmask
255.255.255.255
3、为了使响应报文的源地址为VIP，添加一条路由
RS1:
# route add -host 202.207.178.4 dev lo:0
RS2:
# route add -host 202.207.178.4 dev lo:0
4、在前端两个Director上分别定义规则
# ipvsadm -A -t 202.207.178.4:80 -s rr
# ipvsadm -a -t 202.207.178.4:80 -r 202.207.178.8 -g
# ipvsadm -a -t 202.207.178.4:80 -r 202.207.178.9 -g
二、安装配置keepalived，并对此系统进行测试！
Director1:
1、安装keepalived
# tar xf keepalived-1.2.1.tar.gz
# cd keepalived-1.2.1
# ./configure --with-kernel-dir=/usr/src/kernels/2.6.32-642.11.1.el6.i686/
# make && make install
注意：
可能需要安装此包：
# yum install popt-devel
发现/usr/src/kernels/为空，需要安装内核源码
# yum install kernel-devel
2、配置keepalived
1）设置一个变量
# DIR=/usr/local/
2）执行如下语句，将keepalived的配置文件放置在/etc下相关目录中
# cp $DIR/etc/rc.d/init.d/keepalived /etc/rc.d/init.d/
# cp $DIR/etc/sysconfig/keepalived /etc/sysconfig/ && mkdir -p
/etc/keepalived
# cp $DIR/sbin/keepalived /usr/sbin/
3）为keepalived提供配置文件
# vim /etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
#定义出现故障向何处发邮件
notification_email {
[email protected]
}
#定义邮件是由谁发的
notification_email_from [email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
#定义检测脚本（为了完成主从节点的切换）
vrrp_script chk_schedown {
script "[ -e /etc/keepalived/down ] && exit 1 || exit 0"
interval 1
weight -5
fail 2
rise 1
}
# VIP1
#用来定义虚拟路由（vrrp实例）
vrrp_instance VI_1 {
state MASTER
#定义通告信息基于那个接口发送和虚拟路由是工作在那个接口上的
interface eth0
# lvs_sync_daemon_inteface eth0
virtual_router_id 51
#定义优先级
priority 101
#定义每隔多长时间发一次通告
advert_int 5
#定义认证
authentication {
#定义认证类型为简单字符认证
auth_type PASS
auth_pass keepalivedpass
}
#定义虚拟地址
virtual_ipaddress {
202.207.178.4/16 dev eth0 label eth0:0
}
#定义自己写的脚本何时执行
track_script {
chk_schedown
}
}
virtual_server 202.207.178.4 80 {
delay_loop 6
lb_algo rr
lb_kind DR
nat_mask 255.255.255.0
protocal TCP
sorry_server 127.0.0.1 80
real_server 202.207.178.8 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
real_server 202.207.178.9 80 {
weight 1
HTTP_GET {
url {
path /
status_code 200
}
connect_timeout 2
nb_get_retry 3
delay_before_retry 1
}
}
}
4）启动服务
# /etc/init.d/keepalived restart
# ps -ef | grep keepalived
此时发现服务已经启动！
# tail -fn 100 /var/log/messages
此时发下一直滚屏，是缺少一个模块，下面加载此模块
# modprobe ip_vs
# /etc/init.d/keepalived restart
# tail -fn 100 /var/log/messages
此时一切正常
Director2：
配置同主节点，只是在配置文件中修改以下几项即可：
priority 100
real_server 202.207.178.9 80
测试：此时访问http://202.207.178.4/，可以发现以轮询方式访问到后端RS；在/etc/keepalived下touch一个名为down的文件，即可实现主从节点的切换！
三、自写脚本，实现DR宕机，向管理员发邮件（在主从节点上同时执行）
# cd /etc/keepalived/
# vim notify.sh
添加如下内容：
#!/bin/bash
#
contact=‘[email protected]‘
Usage(){
echo "Usage: `basename $0` {master|backup|fault} VIP"
}
Notify(){
subject="`hostname`‘s state changed to $1"
mailbody="`data "+%F %T "`: `hostname`‘s state change to $1, $VIP floating."
echo $mailbody | mail -s "$subject" $contact
}
[ $# -lt 2 ] && Usage && exit
VIP=$2
case $1 in
master)
Notify master
;;
backup)
Notify backup
;;
fault)
Notify fault
;;
*)
Usage
exit 1
;;
esac
# chmod +x notify.sh
# vim keepalived.conf
在vrrp段添加如下内容：
notify_master "/etc/keepalived/notify.sh master 202.207.178.4"
notify_backup "/etc/keepalived/notify.sh backup 202.207.178.4"
notify_fault "/etc/keepalived/notify.sh fault 202.207.178.4"
此时在两个节点重启keepalived服务，实现主从节点切换，即可收到邮件！
欢迎批评指正！