Ubuntu 14.04
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HAProxy : HTTP Load Balancing
2016/01/07
 
Install HAProxy to configure Load Balancing Server.
This example based on the environment like follows. 
       |
-------+-----------------------------------------------
       |
       +-------------------+--------------------+
       |10.0.0.30          |10.0.0.31           |10.0.0.32
 +-----+-----+     +-------+------+     +-------+------+
 | Frontend  |     |   Backend#1  |     |   Backend#2  |
 |  HAProxy  |     |  Web Server  |     |  Web Server  |
 +-----------+     +--------------+     +--------------+
 
Configure Servers that HTTP connections to HAProxy Server are forwarded to backend Web Servers.
[1] Install HAProxy.
root@dlp:~#
apt-get -y install haproxy
[2] Configure HAProxy.
root@dlp:~#
mv /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy.cfg.org

root@dlp:~#
vi /etc/haproxy/haproxy.cfg
# create new

global
      # for logging section

    log         127.0.0.1 local2 info
    chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
      # max per-process number of connections

    maxconn     256
      # process' user and group

    user        haproxy
    group       haproxy
      # makes the process fork into background

    daemon

defaults
      # running mode

    mode               http
      # use global settings

    log                global
      # get HTTP request log

    option             httplog
      # timeout if backends do not reply

    timeout connect    10s
      # timeout on client side

    timeout client     30s
      # timeout on server side

    timeout server     30s
# define frontend ( set any name for "http-in" section )

frontend http-in
      # listen 80

    bind *:80
      # set default backend

    default_backend    backend_servers
      # send X-Forwarded-For header

    option             forwardfor
# define backend

backend backend_servers
      # balance with roundrobin

    balance            roundrobin
      # define backend servers

    server             www01 10.0.0.51:80 check
    server             www02 10.0.0.52:80 check
root@dlp:~#
sed -i -e "s/^ENABLED=0/ENABLED=1/g" /etc/default/haproxy

root@dlp:~#
/etc/init.d/haproxy start

* Starting haproxy haproxy
...done.
[3] Configure Rsyslog to get logs for HAProxy.
root@dlp:~#
vi /etc/rsyslog.conf
# line 18,19: uncomment, line 17: add

$ModLoad imudp
$UDPServerRun 514
$AllowedSender UDP, 127.0.0.1
root@dlp:~#
vi /etc/rsyslog.d/50-default.conf
# line 9: change and add like follows

*.*;auth,authpriv.none;local2.none              -/var/log/syslog
local2.*                        /var/log/haproxy.log
root@dlp:~#
initctl restart rsyslog

[4] Change Apache2 settings on Backends to logging X-Forwarded-For header.
root@node01:~#
a2enmod remoteip 

Enabling module remoteip.
To activate the new configuration, you need to run:
  service apache2 restart
root@node01:~#
vi /etc/apache2/apache2.conf
# line 206-209: change like follows

# specify HAProxy server's IP address for RemoteIPInternalProxy

RemoteIPHeader X-Forwarded-For
RemoteIPInternalProxy 10.0.0.30

LogFormat "%v:%p
%a
%l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined
LogFormat "
%a
%l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined
root@node01:~#
/etc/init.d/apache2 restart 

 * Restarting web server apache2
   ...done.
[5] Make sure it works fine to access to the frontend server from a Client with HTTP like follows.
 
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