HAProxy : HTTP Load Balancing2015/02/18

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 connection to HAProxy Server is forwarded to backend Web Servers.
[1]	Install HAProxy.

[root@dlp ~]#

yum -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 10.0.0.31:80 check
    server             www02 10.0.0.32:80 check

[root@dlp ~]#

systemctl start haproxy

[root@dlp ~]#

systemctl enable haproxy

[3]	Configure Rsyslog to get logs for HAProxy.

[root@dlp ~]#

vi /etc/rsyslog.conf

# line 15,16: uncomment, lne 17: add

$ModLoad imudp
$UDPServerRun 514

$AllowedSender UDP, 127.0.0.1

# line 54: change like follows

*.info;mail.none;authpriv.none;cron.none

,local2.none

/var/log/messages

local2.*                                                /var/log/haproxy.log

[root@dlp ~]#

systemctl restart rsyslog

[4]	Change httpd settings on Backends to logging X-Forwarded-For header.

[root@www ~]#

vi /etc/httpd/conf/httpd.conf

# line 196: change like follows

LogFormat "

\"%{X-Forwarded-For}i\"

%l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined

[root@www ~]#

systemctl restart httpd

[5]	Make sure all works fine to access to the frontend server from a Client with HTTP like follows.

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