How to release web applications?

Question

I don't really know how to perform deployment from offline development to live webserver correctly in web development. I mostly resort on intuition, but this is more or less what I did until now: I have a web application in python, or php, and I am hosting it on a live webserver. I use an offline development version whose source is under svn.

Now, as I develop the offline version, I will perform commits to the svn. When time has come for release, I could either:

1. copy the code from the offline server to a temporary directory on the live webserver, then swap the old codebase with the new one (eg. with a link), or...
2. have the live webserver work on a checkout svn, and just run svn update.

I normally do the second, although if I have to upgrade the database before the live deployment, I normally write upgrade sql scripts, and run them first on the live database, then checkout.

What are the best practices for this task ?

Answer 1

I recommend leveraging SVN export instead of checkout. This way, you will not expose any of the SVN files to the world. It also generally creates a cleaner folder structure.

I have leveraged rsync before when moving files between stage and production.

My typical deployment proceeds as follows:

• backup production site
• Restore from backup to stage server
• Lock the server down from all external IP addresses
• Export the code from the repository into a temp folder (optionally diff the two folders for small changes)
• rsyc files from the temp folder to the stage server folder
• Validate that only the files you expect to have changed have actually changed.
• Apply SQL scripts to the DB
• Test the upgrade
• Unlock the webserver

Now, to deploy to production, replay these steps in fast forward. Using scripts make it much easier.