一、简介
软件负载均衡一般通过两种方式来实现：基于操作系统的软负载实现和基于第三方应用的软负载实现。
LVS 就是基于 Linux 操作系统实现的一种软负载，HAProxy就是开源的并且基于第三应用实现的软负载。HAProxy 相比 LVS 的使用要简单很多，功能方面也很丰富。当前，HAProxy 支持两种主要的代理模式:"tcp"即 4 层（大多用于邮件服务器、内部协议通信服务器等）和 7 层（HTTP）在 4 层模式下， HAproxy仅在客户端和服务器之间转发双向流量。 7 层模式下， HAProxy 会分析协议，并且能通过允许、拒绝、交换、增加、修改或者删除请求(request)或者回应(response)里指定内容来控制协议，这种操作要基于特定规则。
详情可以HAProxy 官方网站(http://haproxy.1wt.eu)可以下载配置说明文档(configuration.txt)和架构文件(architecture.txt)作为参考。
二、拓扑图
三、 配置过程
注：
OS：Centos 6.5x86_64
己经安装的包组 :
#yum groupinstall -y "Development tools" "Server Platform Development"
前提：
HAproxy A与B要做到
主机名解析
时间同步
无密钥登录
1、HAproxy A配置
安装keepalived、haproxy
#yum install -y keepalived haproxy
配置keepalived
编辑/etc/keepalived/keepalived.conf
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
essuninfo@localhost
}
notification_email_from essuninfo@localhost
smtp_connect_timeout 3
smtp_server 127.0.0.1
router_id LVS_DEVEL
}
vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1
weight 2
}
vrrp_instance VI_1 {
interface eth0
state MASTER
priority 201
virtual_router_id 109
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth0
}
virtual_ipaddress {
172.16.1.103/16 dev eth0 label eth0:0
}
track_script {
chk_haproxy
}
notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
}
vrrp_instance VI_2 {
interface eth0
state BACKUP
priority 99
virtual_router_id 52
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth0
}
virtual_ipaddress {
172.16.1.109/16 dev eth0 label eth0:1
}
track_script {
chk_haproxy
}
}通知脚本
#!/bin/bash
# description: An example of notify script
#
vip=172.16.1.103
contact=‘root@localhost‘
notify() {
mailsubject="`hostname` to be $1: $vip floating"
mailbody="`date ‘+%F\ %T‘`: vrrp transition, `hostname` changed to be $1"
echo $mailbody | mail -s "$mailsubject" $contact
}
case "$1" in
master)
notify master
/etc/rc.d/init.d/haproxy start
exit 0
;;
backup)
notify backup
/etc/rc.d/init.d/haproxy stop
exit 0
;;
fault)
notify fault
/etc/rc.d/init.d/haproxy stop
exit 0
;;
*)
echo ‘Usage: `basename $0` {master|backup|fault}‘
exit 1
;;
esac
#chmod +x /etc/keepalived/notify.sh配置haproxy
编辑配置文件 /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# Example configuration for a possible web application. See the
# full configuration options online.
#
# http://haproxy.1wt.eu/download/1.4/doc/configuration.txt
#
#---------------------------------------------------------------------
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global #全局配置区域
log 127.0.0.1 local2 #日志将通过rsyslog进行归档记录
chroot /var/lib/haproxy #运行的安装路径
pidfile /var/run/haproxy.pid #pid文件存放的位置
maxconn 4000 #最大连接
user haproxy #运行haproxy的用户
group haproxy #运行haprixy的组
daemon #以后台模式运行haproxy
# turn on stats unix socket
stats socket /var/lib/haproxy/stats
#---------------------------------------------------------------------
# common defaults that all the ‘listen‘ and ‘backend‘ sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
mode http #工作模式
log global #记录日志
option httplog
option dontlognull #不记录健康检查的日志信息
option http-server-close #启用服务器端主动关闭
option forwardfor except 127.0.0.0/8 #传递客户端IP
option redispatch #当后端服务器组中的某一台主机故障后，能够自动将请求重定向到组内的其它主机
retries 3 #请求重试次数
timeout http-request 10s #http请求超时时间
timeout queue 1m #一个请求在队列里的超时时间
timeout connect 10s #连接服务器超时时间
timeout client 1m #客户端超时时间
timeout server 1m #客户端超时时间
timeout http-keep-alive 10s
timeout check 10s #心跳检测超时时间
maxconn 3000 #最大连接数
#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend proxy *:80
acl url_static path_beg -i /static /images /javascript /stylesheets
acl url_static path_end -i .jpg .gif .png .css .js
use_backend static if url_static
default_backend dynamic
#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static #后端调度
balance roundrobin #调度算法
server web2 192.168.1.108:80 inter 1500 rise 2 fall 3 check maxconn 5000
#----------------------------------------
listen statistics
mode http # http 7 层模式
bind *:8080 #监听地址
stats enable #启用状态监控
stats auth admin:essun #验证的用户与密码
stats uri /admin?status #访问路径
stats admin if TRUE #如果验证通过了就允许登录
stats refresh 6s #每6秒刷新一次
acl allow src 172.16.1.0/24 #允许的IP地址
tcp-request content accept if allow #如果允许的地址段就允许访问
tcp-request content reject #拒绝非法连接
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend dynamic
balance roundrobin
server web2 192.168.1.40:80 check inter 1500 rise 2 fall 3 maxconn 5000
#服务器定义，serverid为web2，check inter 1500是检测心跳频率
#rise 2是2次正确认为服务器可用
#fall 3是3次失败认为服务器不可用
#最大连接数据为5000
server web3 192.168.1.104:80 check inter 1500 rise 2 fall 3 maxconn 5000将此文件同时也复制到HAproxy B上一份
2、HAproxy B的配置
安装keepalived、haproxy
#yum install -y keepalived haproxy
修改keepalived在配置文件（/etc/keepalived/keepalived.conf）
! Configuration File for keepalived
global_defs {
notification_email {
root@localhost
essuninfo@localhost
}
notification_email_from essuninfo@localhost
smtp_connect_timeout 3
smtp_server 127.0.0.1
router_id LVS_DEVEL
}
vrrp_script chk_haproxy {
script "killall -0 haproxy"
interval 1
weight 2
}
vrrp_instance VI_1 {
interface eth0
state BACKUP
priority 200
virtual_router_id 109
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth0
}
virtual_ipaddress {
172.16.1.103/16 dev eth0 label eth0:0
}
track_script {
chk_haproxy
}
}
vrrp_instance VI_2 {
interface eth0
state MASTER
priority 100
virtual_router_id 52
garp_master_delay 1
authentication {
auth_type PASS
auth_pass password
}
track_interface {
eth0
}
virtual_ipaddress {
172.16.1.109/16 dev eth0 label eth0:1
}
track_script {
chk_haproxy
}
notify_master "/etc/keepalived/notify.sh master"
notify_backup "/etc/keepalived/notify.sh backup"
notify_fault "/etc/keepalived/notify.sh fault"
}修改通知脚本
#!/bin/bash
# description: An example of notify script
#
vip=172.16.1.109
contact=‘root@localhost‘
notify() {
mailsubject="`hostname` to be $1: $vip floating"
mailbody="`date ‘+%F\ %T‘`: vrrp transition, `hostname` changed to be $1"
echo $mailbody | mail -s "$mailsubject" $contact
}
case "$1" in
master)
notify master
/etc/rc.d/init.d/haproxy start
exit 0
;;
backup)
notify backup
/etc/rc.d/init.d/haproxy stop
exit 0
;;
fault)
notify fault
/etc/rc.d/init.d/haproxy stop
exit 0
;;
*)
echo ‘Usage: `basename $0` {master|backup|fault}‘
exit 1
;;
esac
#chmod +x /etc/keepalived/notify.sh由于HAproxy A中的haporxy配置与HAporxy B 的配置文件相同从HAproxy A中发过来一份放在同一目录下即可
#scp -p /etc/haproxy/haproxy.cnf 192.168.1.109:/etc/haproxy/
3、测试一下keepalived功能
HAproxy B 上面的ip地址
将ha2上的keepalived停止后，ip地址己经转移到了ha1上了
当ha2启动后，172.16.1.109还是会回到ha2上面。
4、安装后端的web服务
web1 静态页面 （192.168.1.108）
#yum install -y httpd
[root@essun ~]# cd /var/www/html/
[root@essun html]# echo "<h1>这是一个静态页面，地址为192.168.1.108</h1>" > index.html
[root@essun html]# ll
total 4
-rw-r--r-- 1 root root 59 May 3 12:50 index.html
[root@essun html]# cat index.html
<h1>这是一个静态页面，地址为192.168.1.108</h1>
[root@essun html]# service httpd start
Starting httpd: httpd: apr_sockaddr_info_get() failed for essun.node3.com
httpd: Could not reliably determine the server‘s fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
[root@essun html]# curl http://192.168.1.108
<h1>这是一个静态页面，地址为192.168.1.108</h1>在/var/www/html中放一张图片，仅供测试
web2 动态页面 (192.168.1.40)
[root@essun yum.repos.d]# yum install -y httpd php php-mysql mysql-server mysql-devel
[root@essun yum.repos.d]# cd /var/www/html/
[root@essun html]# vim index.php
[root@essun html]# service httpd restart
Stopping httpd: [FAILED]
Starting httpd: httpd: apr_sockaddr_info_get() failed for essun.node4.com
httpd: Could not reliably determine the server‘s fully qualified domain name, using 127.0.0.1 for ServerName
[ OK ]
[root@essun html]# cat index.php
<h1>我是动态页面，地址是192.168.1.40</h1>
<?php
phpinfo();
?>
[root@essun html]# curl -I http://192.168.1.40/index.php
HTTP/1.1 200 OK
Date: Sat, 03 May 2014 05:11:47 GMT
Server: Apache/2.2.15 (CentOS)
X-Powered-By: PHP/5.3.3
Connection: close
Content-Type: text/html; charset=UTF-8web3 动态页面（192.168.1.104）
[root@essun yum.repos.d]# yum install -y httpd php php-mysql mysql-server mysql-devel
[root@essun yum.repos.d]# cd /var/www/html/
[root@essun html]# vim index.php
[root@essun yum.repos.d]# service httpd restart
Stopping httpd: [FAILED]
Starting httpd: [ OK ]
[root@essun html]# cat index.php
<h1>我也是动态页面，地址是192.168.1.104</h1>
<?php
phpinfo();
?>
[root@essun yum.repos.d]# curl -I http://192.168.1.104
HTTP/1.1 200 OK
Date: Sat, 03 May 2014 05:14:22 GMT
Server: Apache/2.2.15 (CentOS)
X-Powered-By: PHP/5.3.3
Connection: close
Content-Type: text/html; charset=UTF-8四、测试
1、利用两个vip任意一个测试一下
静态页面测试
动态页面测试web2 (192.168.1.40)
动态页面测试 web3 （192.168.1.104）
监控页面，验证用户身份
验证通过后
其中一个keepalived宕机后完不会影响到服务的正常的运行
===================================完===================================================
本文出自 “和风细雨” 博客，请务必保留此出处http://essun.blog.51cto.com/721033/1405893
原文：http://essun.blog.51cto.com/721033/1405893