1、要解决的问题 （1）后台web server要考虑扩容和负载均衡； （2）要保护后台webserver ，避免webserver 由于负载过高，造成系统不可用 2、试验环境
haproxy：HA-Proxy version 1.6.0 2015/10/13
apache2 ：
Server version: Apache/2.4.7 (Ubuntu)
Server built: Jan 14 2016 17:45:23
目的：所有访问 192.168.1.2:80 的web 请求，会通过 haproxy 均衡的分配给为 192.168.1.2:8001 192.168.101.2:8002 ，这是两个监听不同端口的apache 服务器;
3、解决思路
让所有 访问haproxy的请求都转发给，8001 和 8002 ,haprxy 要对这些请求进行调度，由8001 和8002 进行实际的处理php 文件
4、配置文件
haproxy ：配置文件路径：/etc/haproxy/haproxy.cfg
```
global
log 127.0.0.1 local0
#maxconn 20000
#uid 535 #uid和gid按照实际情况进行配置
#gid 520
#chroot /var/chroot/haproxy
daemon
nbproc 1
defaults
log global
mode http
option httplog
#option httpclose
option dontlognull
#option forwardfor
option redispatch
retries 3
balance roundrobin
maxconn 1000
stats uri /haproxy-stats
timeout connect 5000
timeout client 50000
timeout server 50000
#frontend http-in
bind *:80
default_backend pool1
#backend pool1
option httpchk HEAD / HTTP/1.0
stats refresh 2
server WEB1 127.0.0.1:81 weight 3 maxconn 10000 check
server WEB2 127.0.0.1:82 weight 3 maxconn 10000 check
listen webfarm 192.168.101.129:80 mode http stats enable stats uri /haproxy?stats stats realm Haproxy\ Statistics stats auth haproxy:stats balance roundrobin cookie LBN insert indirect nocache option httpclose option forwardfor server web01 192.168.101.129:8001 cookie node1 check server web02 192.168.101.129:8002 cookie node2 check
haproxy 操作命令：service haproxy start/stop/restart
apache 配置:
/etc/apache2/ports.conf 增加监听8001 和 8002 注释掉监听80，因为haproxy 要监听80
```
#Listen 80
Listen 8001
Listen 8002
<IfModule ssl_module>
Listen 443
</IfModule>
<IfModule mod_gnutls.c>
Listen 443
</IfModule>
/etc/apache2/sites-available/8001.conf 主要是端口和web目录，web目录下只有一个php 文件
<VirtualHost *:8001>
# The ServerName directive sets the request scheme, hostname and port that
# the server uses to identify itself. This is used when creating
# redirection URLs. In the context of virtual hosts, the ServerName
# specifies what hostname must appear in the request's Host: header to
# match this virtual host. For the default virtual host (this file) this
# value is not decisive as it is used as a last resort host regardless.
# However, you must set it for any further virtual host explicitly.
#ServerName www.example.com
ServerAdmin webmaster@localhost
DocumentRoot /var/www/html/8001/
# Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
# error, crit, alert, emerg.
# It is also possible to configure the loglevel for particular
# modules, e.g.
#LogLevel info ssl:warn
ErrorLog ${APACHE_LOG_DIR}/error.log
CustomLog ${APACHE_LOG_DIR}/8001_access.log combined
# For most configuration files from conf-available/, which are
# enabled or disabled at a global level, it is possible to
# include a line for only one particular virtual host. For example the
# following line enables the CGI configuration for this host only
# after it has been globally disabled with "a2disconf".
#Include conf-available/serve-cgi-bin.conf
</VirtualHost>
/etc/apache2/sites-available/8002.conf 与8001 类似，除了端口和web目录不同
启动8001 和8002 :sudo a2ensite 8801 ;sudo a2ensite 8002 重启apache ：sudo service apache2 restart
验证步骤： （1）从另外一台机器使用 ab -c 10 -n 1000 http://192.168.1.2/，待测试结束后，查看access_log，可以看到相应的增加 （2）调整haproxy.conf 中的maxconn 与ab -c 10 并发数，可以看到这个maxconn 会起到限流作用 比如：maxconn 设置为3 则 ab -c 10 需要花费较长时间完成 若maxconn 为20 ，则 ab -c 10 则较快即可完成 5、主要参考资料 https://linux.cn/article-4765-1.html#2_3510 https://cbonte.github.io/haproxy-dconv/configuration-1.5.html
来源：oschina
链接：https://my.oschina.net/u/1251232/blog/664105