Install HAproxy for high performance and HA

Install HA-proxy as load balance in webserver

Hello Guys, 

Welcome back again on my rathinavneet.blogspot.in.

 I will tell you how you can setup your HA proxy in 10 min for high availability from source so that if one of your web server down it wont affect you much.as your other server are working just fine and your company's or clients business is uninterrupted.

          HA  proxy work on transport layer protocol so same proxy can be use for multiple application.

It will server a great like same ha proxy can be used to configure the Mysql server as well as apache web-server or nginx or tomcat and many more.You will also get the statistics of the network in real time look at the image below.

 Look in the image you can see that  its showing the working web-server by green.Stop or not working or not responding web server by red.

Its working as proxy server as well as a load balance.

Lets start with installation and configuration.I am using ubuntu 12.04 as my host machine.

so 

apt-get install haproxy

This will do the trick and install haproxy fro me.

 We also need to enable the ha proxy in init script so edit the following file 

nano /etc/default.haproxy

 enable = 1

 

Then start with the configuration first of all backup your existing haproxy.conf file to haproxy.back file

mv /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy.cfg.back

global
        log 127.0.0.1   local0
        log 127.0.0.1   local1 notice
        maxconn 4096
        user haproxy
        group haproxy

The log directive mentions a syslog server to which log messages will be sent. On Ubuntu rsyslog is already installed and running but it doesn't listen on any IP address. We'll modify the config files of rsyslog later.
The maxconn directive specifies the number of concurrent connections on the frontend. The default value is 2000 and should be tuned according to your VPS' configuration.
The user and group directives changes the HAProxy process to the specified user/group. These shouldn't be changed.

defaults
    log     global
    mode    http
    option  httplog
    option  dontlognull
    retries 3
    option redispatch

    maxconn 4096 

    timeout connect  5000
    timeout client  50000
    timeout server  50000

We're specifying default values in this section. The values to be modified are the various timeout directives. The connect option specifies the maximum time to wait for a connection attempt to a VPS to succeed.
The client and server timeouts apply when the client or server is expected to acknowledge or send data during the TCP process. HAProxy recommends setting the client and server timeouts to the same value.
The retries directive sets the number of retries to perform on a VPS after a connection failure.
The option redispatch enables session redistribution in case of connection failures. So session stickness is overriden if a VPS goes down.

On Web-server 1 & 2
Create a file in web-servers called check.txt using command  and we will configure the same in ha proxy to check for the particular file if file found when server is ping that means server is operational.
for HA-proxy and proxy will show it as green in the panel.

listen ApplicationCluster 192.168.1.100:80
       mode http
       stats enable
       stats auth nrathi:nrathi123
       balance roundrobin
       cookie JSESSIONID prefix
       option httpclose
       option forwardfor
       option httpchk HEAD /check.txt HTTP/1.0

       server webserver1 192.168.1.102:80 cookie A check
       server webserver2 192.168.1.103:80 cookie B check

This contains configuration for both the frontend and backend. We are configuring HAProxy to listen on port 80 for appname which is just a name for identifying an application. The stats directives enable the connection statistics page and protects it with HTTP Basic authentication using the credentials specified by the stats auth directive.
This page can viewed with the URL mentioned in stats uri so in this case, it is http://192.168.1.100/haproxy?stats

a demo of this page can be viewed here.

The balance directive specifies the load balancing algorithm to use. Options available are Round Robin (roundrobin), Static Round Robin (static-rr), Least Connections (leastconn), Source (source), URI (uri) and URL parameter (url_param).
Information about each algorithm can be obtained from the official documentation.
The server directive declares a backend server, the syntax is:
server <name> <address>[:port] [param*] 

  The name we mention here will appear in logs and alerts. There are many paratmeters supported by this directive and we'll be using the check and cookie parameters in this article. The check option enables health checks on the VPS otherwise, the VPS is
always considered available.
Once you're done configuring start the HAProxy service:
 
sudo service haproxy start

SO the sample configuration file is as follows:

global
        log 127.0.0.1   local0
        log 127.0.0.1   local1 notice
        #log loghost    local0 info
        maxconn 4096
        #debug
        #quiet
        user haproxy
        group haproxy

defaults
    log     global
    mode    http
    option  httplog
    option  dontlognull
    retries 3

    option redispatch

    maxconn 4096 

    timeout connect  5000
    timeout client  50000
    timeout server  50000

 

listen webfarm 192.168.1.100:80
       mode http
       stats enable
       stats auth someuser:somepassword
       balance roundrobin
       cookie JSESSIONID prefix
       option httpclose
       option forwardfor
       option httpchk HEAD /check.txt HTTP/1.0
       server webA 192.168.1.102:80 cookie A check
       server webB 192.168.1.103:80 cookie B check 

# and thats it we are ready to go.