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Load Balancing with HAProxy

Discussion in 'Engineering Concepts' started by pradeep, Mar 15, 2013.

  1. pradeep

    pradeep Team Leader

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    HAProxy stands for High Availability Proxy, is an open-source TCP/HTTP load balancer. In case you are new to the idea of a load balancer, the work of a load balancer is to distribute incoming requests to an array of upstream servers so as no single upstream server is overworked/overloaded by the incoming requests.

    HAProxy has been reported to be highly efficient and fault tolerant, and it is also claimed that HAProxy has never crashed in a production environment. HAProxy is very configurable, you can chose for a variety of load balancing algorithms like Round-Robin, Source, LeastConn, etc., it also provides support for sticky session, provides detailed logs and monitoring stats. In this article we'll look at installing and setting up a basic HAProxy load balancer.

    Installing HAProxy



    Firstly, download the source tarball from HAProxy official website (http://haproxy.1wt.eu/), then untar, build and install:

    Code:
    $ tar -zvxf haproxy-1.4.22.tar.gz
    $ cd haproxy-1.4.22
    $ make
    $ cp haproxy /usr/sbin/haproxy
    
    Now, you have built and copied the standalone HAProxy executable to the sbin directory, you can run haproxy as a command.

    Configuring HAProxy



    There are lots of configuration options, it can be as easy as the installation or something very complicated, it all depends on your requirements. Here we'll look at a very simple configuration example, I've added comments for easier understanding of the configuration directives, you can find the complete configuration guide on the HAProxy website (http://haproxy.1wt.eu/#docs)

    You can put the HAProxy configuration file wherever you want, for example I put it in /etc/conf/haproxy.conf

    Code:
    ## global options
    global
        ## maximum allowed connections
        maxconn 10000
        ## path to the PID file
        pidfile /var/run/haproxy.pid
        ## specify to run as a daemon
        daemon 
    
    defaults
        ## conifgure to server HTTP requests
        mode http
        ## maintain HTTP requests log
        option httplog
        ## add X-Forwarded-For header
        option forwardfor
       
    listen http haproxy.go4expert.com:80
        mode tcp
        option tcplog
        ## specify algorithm
        balance roundrobin
        maxconn 10000
        ## specify server array
        server appserver1 192.168.1.1:80 
        server appserver2 192.168.1.2:80
    
    To start HAProxy with the configuration issue the following command:

    Code:
    $ haproxy -f /etc/conf/haproxy.conf
    
    To view the stats, the URL would be haproxy.go4expert.com/haproxy?stats

    I hope it has been helpful to you, post your experiences so that we all can share and learn.
     

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