Best way to manage code changes for application in Amazon EC2 with Auto Scaling

Question

I have multiple instances running behind Load balancer with Auto Scaling in AWS.

Now, if I have to push some code changes to these instances and any new instances that m

Answer 1

The way I do my code changes is to have a master server which I edit on the code on. All the slave servers which scale then rsync via ssh by a cron job to bring all the files up to date. All the servers sync every 30 minutes +- a few random seconds to keep from accessing it at the exact same second. (note I leave the Master off of the load balancer so users always have the same code being sent to them. Similarly, when I decide to publish my code changes, I do an rsync from my test server to my master server.

Using this approach, you merely have to put the sync command in the start-up and you don't have to worry about what the code state was on the slave image as it will be up to date after it boots.

EDIT: We have stopped using this method now and started using the new service AWS CodeDeploy which is made for this exact purpose:

http://aws.amazon.com/codedeploy/

Hope this helps.