HA-proxy

Setup dns for the virtual ip, then setup Corosync before starting with this guide.

HA-proxy is short for High Availibility proxy. It has features to check that the servers behind it are up, and round robins incoming requests between the servers. HA-proxy can be used with various server types. We will configure two HA-proxys, which later will be running an active/passive setup with Corosync

Software

apt-get install haproxy

Configuration

Apache

Add the following to /etc/haproxy/haproxy.cfg 

listen webfarm 
        bind www:80
        mode http
        balance roundrobin
        cookie LBN insert indirect nocache
        option httpclose
        option forwardfor
        server haproxy01 www01:80 cookie node1 check
        server haproxy02 www02:80 cookie node2 check