How to Setup HAproxy Load Balance Server for Sharing Web Traffic

This article is written to prepare high availability of a website. This can also be used by those who want their website to be available to their clients or users with high availability servers and to share between their servers. It is a free and open source application used as a TCP/HTTP load balancer which will distribute web traffic to multiple servers and improves performance and reliability of the web server.
Assume that load balancer HA proxy server IP address is http://192.167.57.150
OS: Centos 6.7, IP Address: 192.168.57.150
OS: Centos 6.7, IP Address: 192.168.57.147
OS: Centos 6.7, IP Address: 192.168.57.148
We need to install the Apache on both the web servers, i.e., 192.168.57.151 and 192.168.57.152.
# yum install http*
After installation, please access the Apache from web browser http://your-server-ip-address
# yum install haproxy openssl-devel
Open the host files and add the below lines in all 3 servers (HAproxy Load balancer, webserver1, webserver2)
192.168.87.150    haproxy.demo.com    haproxy

192.168.87.151    webserv1.demo.com    haproxy
192.168.87.152    webserv2.demo.com    haproxy
# vi /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.87.150    haserver.cgi.com    haserver
192.168.87.151    ha2.cgi.com ha2
192.168.87.152    ha1.cgi.com ha1
Now, you need to enable the HAproxy Logs to identify the problems for your future debugging
# vi /etc/haproxy/haproxy.cfg
Add these below lines to enable the logging
log 127.0.0.1 local Needed to enable the UDp SYSLOG reception in /etc/rsyslog.conf
# vi /etc/rsyslog.conf
#### MODULES ####

$ModLoad imuxsock # provides support for local system logging (e.g. Via logger command)
$ModLoad imklog # provides kernel logging support (previously done by rklogd)
#$ModLoad immark # provides --MARK-- message capability

# Provides UDP syslog reception
$ModLoad imudp
$UDPServerRun 514

# Provides TCP SYSLOG reception
#$ModLoad imtcp
#$InputTCPServerRun 514
Now create a haproxy.conf in /etc/rsyslog.d/ folder to create log files
# vi /etc/rsyslog.d/haproxy.conf
Add the below line to create the file
local.* /var/log/haproxy.log
Restart the rsyslog services to update the changes we made
# service rsyslog restart
Configuring HAproxy global settings
we needed to setup the glogal setting in /etc/haproxy/haproxy.cfg
# vi /etc/haproxy/haproxy.cfg
#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
mode                       http
log                        global
option                     httplog
option                     dontlognull
option http-server-close
option forwardfor          except 127.0.0.0/8
option                     redispatch
retries                    3
timeout http-request       10s
timeout queue              1m
timeout connect            10s
timeout client             1m
timeout server             1m
timeout http-keep-alive    10s
timeout check 10s
maxconn 3000
We have to provide the details of both the web servers as front-end and back-end servers in case of failure.
frontend LB
   bind 192.168.87.150:80
   reqadd X-Forwarded-Proto: http
   default_backend LB

backend LB 192.168.87.150:80
   mode http
   stats enable
   stats hide-version
   stats uri /stats
   stats realm Haproxy Statistics
   stats auth haproxy:redhat            # Credentials for HAProxy Statistic report page.
   balance roundrobin                   # Load balancing will work in round-robin process.
   option httpchk
   option httpclose
   option forwardfor
   cookie LB insert
   server ha2 192.168.87.151:80 cookie ha1 check           # backend server.
   server ha1 192.168.87.152:80 cookie ha2 check           # backend server.
We need to restart the services and make the changes effective.
# service haproxy restart
To start the service automatically, use the below command
# chkconfig haproxy on
To check the autostart –
# chkconfig --list haproxy
After the services, re-start so that, we can access the load balancer on http://192.168.87.150:/stats
For testing the HAproxy load balancer, we will have to create an index.html file in both web servers with below code.
Create an index.html file in the webserver1 with the bellow code.
<html>
<head>
   <title>HAProxy Test Page</title>
</head>
   <body>
      <!-- Main content -->
      <h1>My HAProxy Test Page Server 1 </h1>
   </body>
</html>
Create an index.html file in webserver2 with the bellow code.
<html>
<head>
   <title>HAProxy Test Page</title>
</head>
   <body>
      <!-- Main content -->
      <h1>My HAProxy Test Page Server 2 </h1>
   </body>
</html>
Now access the haproxy server IP http://192.168.57.150
By default, you can see the page of webserver 1
Webserver1
Now, test the load balance by going to webserver 1 and stop the HTTPd server
# service httpd stop
Then, access the haproxy server IP, http://192.168.57.150
Now, you will see the web page of webserver2 automatically
Webserver2
To verify, you can access the HAproxy load balancer statistics page http://192.168.87.150/stats
HAproxy
After the configuration, you should be able to get your website without interruption even if one of the servers is down or unavailable. In the same way, we can also set up a HAproxy for Apache. You can also observe that, Webserver1 is not accessible or Down in the HAproxy load balancer statistics page by configuring the above as shown. You can also add any number of servers depending upon the requirement.