Haproxy服务器：192.168.1.112
Apache服务器：192.168.1.12:80（此为自己配置的一个简单apache网页服务器）
百度服务器： 115.239.210.26:80（此为百度网页ip地址）
由于访问百度网页的网友很多，会造成拥堵延时访问。现假设百度有2个网页服务器（一样），服务器ip地址分别为：192.168.1.12:80，115.239.210.26:80。当请求www.baidu.com 的时候，haproxy代理服务会平均分配请求次数到两个服务器中，达到了负载均衡的效果。若把192.168.1.12:80中的apache暂停（偶然破坏），则此服务不再被访问，所有访问都将请求115.239.210.26:80。
Haproxy服务器安装在虚拟机centos5.6中，apache网页服务在虚拟机window2003中，虚拟机都以桥接方式与主机连接，都设置成静态IP地址。因此两台虚拟机和主机形成了简单局域网。
Window2003域名和IP绑定：
在文件C:\WINDOWS\system32\drivers\etc\hosts 添加192.168.1.12 www.baidu.com
CentOS域名和IP绑定：
编辑文件vi /etc/hosts 添加 192.168.1.112 www.baidu.com
如果想在主机访问测试：
在文件C:\WINDOWS\system32\drivers\etc\hosts 添加192.168.1.112 www.baidu.com
1.安装
cd /usr/local/
wget http://haproxy.1wt.eu/download/1.3/src/haproxy-1.3.20.tar.gz
tar zxvf haproxy-1.3.20.tar.gz
cd haproxy-1.3.20
make TARGET=linux26 PREFIX=/usr/local/haproxy #将haproxy安装到/usr/local/haproxy
make install PREFIX=/usr/local/haproxy
2.配置
cd /usr/local/haproxy-1.3.20/examples/
cp haproxy.cfg/usr/local/haproxy/
cd usr/local/haproxy
vi haproxy.cfg
#修改前（默认配置）：
# this config needs haproxy-1.1.28 or haproxy-1.2.1
global
log 127.0.0.1 local0
log 127.0.0.1 local1 notice
#log loghost local0 info
maxconn 4096
chroot /usr/share/haproxy
uid 99
gid 99
daemon
#debug
#quiet
defaults
log global
mode http
option httplog
option dontlognull
retries 3
redispatch
maxconn 2000
contimeout 5000
clitimeout 50000
srvtimeout 50000
listen appli1-rewrite 0.0.0.0:10001
cookie SERVERID rewrite
balance roundrobin
server app1_1 192.168.34.23:8080 cookie app1inst1 check inter 2000 rise 2 fall 5
server app1_2 192.168.34.32:8080 cookie app1inst2 check inter 2000 rise 2 fall 5
server app1_3 192.168.34.27:8080 cookie app1inst3 check inter 2000 rise 2 fall 5
server app1_4 192.168.34.42:8080 cookie app1inst4 check inter 2000 rise 2 fall 5
listen appli2-insert 0.0.0.0:10002
option httpchk
balance roundrobin
cookie SERVERID insert indirect nocache
server inst1 192.168.114.56:80 cookie server01 check inter 2000 fall 3
server inst2 192.168.114.56:81 cookie server02 check inter 2000 fall 3
capture cookie vgnvisitor= len 32
option httpclose # disable keep-alive
rspidel ^Set-cookie:\ IP= # do not let this cookie tell our internal IP address
listen appli3-relais 0.0.0.0:10003
dispatch 192.168.135.17:80
listen appli4-backup 0.0.0.0:10004
option httpchk /index.html
option persist
balance roundrobin
server inst1 192.168.114.56:80 check inter 2000 fall 3
server inst2 192.168.114.56:81 check inter 2000 fall 3 backup
listen ssl-relay 0.0.0.0:8443
option ssl-hello-chk
balance source
server inst1 192.168.110.56:443 check inter 2000 fall 3
server inst2 192.168.110.57:443 check inter 2000 fall 3
server back1 192.168.120.58:443 backup
listen appli5-backup 0.0.0.0:10005
option httpchk *
balance roundrobin
cookie SERVERID insert indirect nocache
server inst1 192.168.114.56:80 cookie server01 check inter 2000 fall 3
server inst2 192.168.114.56:81 cookie server02 check inter 2000 fall 3
server inst3 192.168.114.57:80 backup check inter 2000 fall 3
capture cookie ASPSESSION len 32
srvtimeout 20000
option httpclose # disable keep-alive
option checkcache # block response if set-cookie & cacheable
rspidel ^Set-cookie:\ IP= # do not let this cookie tell our internal IP address
errorloc 502 http://192.168.114.58/error502.html
errorfile 503 /etc/haproxy/errors/503.http
#修改后：
# this config needs haproxy-1.1.28 or haproxy-1.2.1
global
log 127.0.0.1 local0
#log loghost local0 info
maxconn 4096
chroot /usr/local/haproxy
nbproc 2
uid 99
gid 99
daemon
#debug
#quiet
defaults
log global
log 127.0.0.1 local0
mode http
option httplog
option dontlognull
option redispatch
retries 3
maxconn 2000
contimeout 5000
clitimeout 10000
srvtimeout 10000
listen stats
mode http
bind 0.0.0.0:1080
stats enable
stats hide-version
stats uri /haproxy-stats
stats auth admin:admin
frontend http-in
bind *:80
mode http
log global
option httpclose
option logasap
option dontlognull
option forwardfor
default_backend servers
backend servers
balance roundrobin
server s1 192.168.1.12:80 weight 3 check
server s2 115.239.210.26:80 weight 3 check
3.添加日志
在最下边增加日志：
vi /etc/syslog.conf
local0.* /var/log/haproxy.log
修改日记参数：
vi /etc/sysconfig/syslog
SYSLOGD_OPTIONS="-r -m 0"
重启日志服务:
service syslog restart
4.设置开机启动，为了方便系统在开机时加载，还可以创建启动脚本：
vi /etc/rc.d/init.d/haproxy
#!/bin/sh
set -e
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/haproxy/sbin
PROGDIR=/usr/local/haproxy
PROGNAME=haproxy
DAEMON=$PROGDIR/sbin/$PROGNAME
CONFIG=$PROGDIR/$PROGNAME.conf
PIDFILE=$PROGDIR/$PROGNAME.pid
DESC="HAProxy daemon"
SCRIPTNAME=/etc/init.d/$PROGNAME
# Gracefully exit if the package has been removed.
test -x $DAEMON || exit 0
start()
{
echo -n "Starting $DESC: $PROGNAME"
$DAEMON -f $CONFIG
echo "."
}
stop()
{
echo -n "Stopping $DESC: $PROGNAME"
haproxy_pid=cat $PIDFILE
kill $haproxy_pid
echo "."
}
restart()
{
echo -n "Restarting $DESC: $PROGNAME"
$DAEMON -f $CONFIG -p $PIDFILE -sf $(cat $PIDFILE)
echo "."
}
case "$1" in
start)
start
;;
stop)
stop
;;
restart)
restart
;;
*)
echo "Usage: $SCRIPTNAME {start|stop|restart}" >&2
exit 1
;;
esac
exit 0
5.执行检查：
保存后赐予可执行权限:
chmod +x /etc/rc.d/init.d/haproxy
chmod +x /usr/local/haproxy/haproxy.cfg
启动 haproxy：（ntsysv）
cd /usr/local/haproxy/sbin
./haproxy -f /usr/local/haproxy/haproxy.cfg
6.常见问题：
[ALERT]109/203959 (6743) : Starting proxy stats: cannot bind socket
查看端口：
netstat –ntpl
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:1080 0.0.0.0:* LISTEN 5659/haproxy
1080或80端口被占用，删除：
kill 5659
再启动;
./haproxy -f /usr/local/haproxy/haproxy.cfg
7.测试：
打开网页(成功)：http://localhost/haproxy-stats
现在Haproxy服务器中打开百度网页 www.baidu.com，不停的用F5刷新，会看到网页时而
打开apache页面，时而打开百度页面（apache页面假设为百度的另一个服务页面）。
模拟一台服务器宕机，停止apache服务，此网页不可访问，因此打开的百度网页都请求到另一个服务中。
相关的haproxy代理统计信息可浏览http://localhost:1080/haproxy-stats查看
资料参考：
http反向代理之haproxy详解
Haproxy 配置项\配置实例
CentOS6下Haproxy的安装配置
Haproxy安装及配置
HAproxy均衡负载部署和配置文件详解
