I have a cluster of Ubuntu 12.04 web servers running a lamp stack. All of these servers are connected to a Load Balancer on Amazon Web Services.

What I want to be able to do is have a dedicated Ubuntu server that I can update the PHP files on and have the other web servers check with cron to get the updates files from the repository. They don't have to use cron but that was the only thing I could think of, unless there was a way to have the updated repository tell them that it has updated files. And then how to transfer those files.

Also if there is a ways for a server to check for updated files when it boots because I am going to be using auto scaling on AWS so when there is an increase in the load and another server gets created I need it to download the updated files from the repository when launched.

Not sure how to transfer files from server to server.