Keepalived 的作用是检测web服务器的状态，如果有一台web服务器死机，或工作出现故障，Keepalived将检测到，并将有故障的web服务器从系统中剔除， 当web服务器工作正常后Keepalived自动将web服务器加入到服务器群中，这些工作全部自动完成，不需要人工干涉，需要人工做的只是修复故障的 web服务器。
HAProxy 提供高可用性、负载均衡以及基于 TCP 和 HTTP 应用的代理,支持虚拟主机,它是免费、快速并且可靠的一种解决方案。HAProxy 特别适用于那些负载特大的 web 站点, 这些站点通常又需要会话保持或七层处理。HAProxy 运行在当前的硬件上,完全可以支持数以万计的并发连接。并且它的运行模式使得它可以很简单安全的整 合进您当前的架构中, 同时可以保护你的 web 服务器不被暴露到网络上。
系统环境: CenOS 6.5x86_64 Desktop install 将selinux and iptables 设置为disabled
主要用到软件：
haproxy-1.5.14.tar.gz
keepalived-1.1.17.tar.gz
nginx-1.7.8.tar.gz
图1 为基本的架构图：
图2 为IP地址分配。
一：安装过程，在两台HA机器上分别keepalived:
#tar -zxvf keepalived-1.2.17.tar.gz
#ln -s /usr/src/kernels/2.6.18-128.el5-i686/ /usr/src/linux
#cd keepalived-1.2.17
[root@test25 keepalived-1.2.17]#./configure--with-kernel-dir=/usr/src/kernels/2.6.32-279.el6.x86_64/
[[email protected]]#make
[[email protected]]#make install
cp /usr/local/etc/rc.d/init.d/keepalived /etc/init.d/
cp/usr/local/etc/sysconfig/keepalived /etc/sysconfig/
mkdir/etc/keepalived/
cp/usr/local/etc/keepalived/keepalived.conf /etc/keepalived/
cp/usr/local/sbin/keepalived /usr/sbin/
修改配置文件为：
Master:
#vim/etc/keepalived/ keepalived.conf
# catkeepalived.conf
! ConfigurationFile for keepalived
vrrp_scriptcheck_haproxy {
script"/etc/keepalived/check_haproxy.sh"
interval 2
weight 2
}
global_defs {
notification_email {
root@localhost
}
[email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instanceVI_1 {
state MASTER
interface eth0
virtual_router_id 151
priority 100
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress{
192.168.1.201
}
track_script {
check_haproxy
}
}
BACKUP:
# catkeepalived.conf
! ConfigurationFile for keepalived
vrrp_scriptcheck_haproxy {
script"/etc/keepalived/check_haproxy.sh"
interval 2
weight 2
}
global_defs {
notification_email {
root@localhost
}
[email protected]
smtp_server 127.0.0.1
smtp_connect_timeout 30
router_id LVS_DEVEL
}
vrrp_instanceVI_1 {
state BACKUP
interface eth0
virtual_router_id 151
priority 50
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress{
192.168.1.201
}
track_script {
check_haproxy
}
}
主机上：
#vi /etc/keepalived/check_haproxy.sh
#!/bin/bash
A=`ps -C haproxy --no-header | wc -l`
if [ $A -eq 0 ];then
/usr/local/haproxy/sbin/haproxy -f/usr/local/haproxy/conf/haproxy.cfg
echo "haproxy start"
sleep 3
if [ `ps -C haproxy --no-header | wc -l`-eq 0 ];then
/etc/init.d/keepalived stop
echo "keepalived stop"
fi
fi
备机上：
#!/bin/bash
A=`ip a | grep 10.2.32.201 | wc -l`
B=`ps -ef | grep haproxy | grep -v grep| awk '{print $2}'`
if [ $A -gt 0 ];then
/usr/local/haproxy/sbin/haproxy -f/usr/local/haproxy/conf/haproxy.cfg
else
kill -9 $B
fi
#两台机器分别执行：chmod 755 /etc/keepalived/check_haproxy.sh
haproxy的安装(主备都一样)：
#tar -zxvf haproxy-1.5.14.tar.gz
#cd haproxy-1.5.14
#make TARGET=linux26 PREFIX=/usr/local/haproxy
#makeinstall PREFIX=/usr/local/haproxy
#cd/usr/local/haproxy/
#mkdir conf
#mkdir logs
#vi haproxy.cfg
global
log127.0.0.1 local0
log127.0.0.1 local1 notice
maxconn 4096
chroot/usr/local/haproxy
uid 99
gid 99
daemon
#debug
#quiet
nbproc 1
pidfile/usr/local/haproxy/logs/haproxy.pid
二：先主后从，两台机器上都分别启动：
/etc/init.d/keepalivedstart （如果之前没有启动haproxy,这条命令会自动把haproxy启动）
[root@test100 haproxy]# ps -ef | grephaprox
root 30344 1 0 11:43 ? 00:00:00 /bin/bash/etc/keepalived/check_haproxy.sh
nobody 30349 1 0 11:43 ? 00:00:00/usr/local/haproxy/sbin/haproxy -f /usr/local/haproxy/conf/haproxy.cfg
[root@test100 haproxy]# ps -ef | grepkeepali
root 30337 1 0 11:43 ? 00:00:00 keepalived -D
root 30339 30337 1 11:43 ? 00:00:00 keepalived -D
root 30340 30337 1 11:43 ? 00:00:00 keepalived -D
root 30372 2876 0 11:43 pts/0 00:00:00 grep keepali
三：测试：
1.再两台HA上分别执行ip ad sh ｜grep 10.2.32
主:
inet10.2.32.100/24 brd 10.2.32.255 scope global eth0
inet10.2.32.201/32 scope global eth0
备:
inet10.2.32.101/24 brd 10.2.32.255 scope global eth0
2.停掉主上的haproxy，3秒后keepalived会自动将其再次启动
3.停掉主的keepalived，备机马上接管服务
备: ip ad sh ｜grep 10.2.32
inet10.2.32.101/24 brd 10.2.32.255 scope global eth0
inet10.2.32.201/32 scope global eth0
四：通过浏览器进行测试
两台web的页面会在你刷新时进行切换。此文将nginx安装，配置过程省略了，如果有问题可以查看以下相关文章。