Jan Mészáros reflections on technology and society

Python virtual environment

Hosting multiple Django projects requires to keep deployment and libraries in control. Imagine, that an one year old Django application is written for Django 0.96, but new projects are written using the actual version 1.1.1. It is possible, of course, to rewrite the old applications to be compatible with the actual version, but rewriting many projects might consume a lot of time.

There is a smart solution to deploy applications using different versions of Django on only one production server. This can be done easily using the "virtualenv" library, which allows you to create unlimited number of python environments including the site-packages directory.

At first, install the virtualenv library with easy_install:

Then, create a new Python virtual environment:

The --no-site-packages parameter avoids access to the global site-packages dir to the virtual environment. Finally, activate the new python environment with command:

Deactivation of the activated environment is done by following command:

Detailed how-to on deploying Django project using the new virtual environment through mod_wsgi is available at http://jmoiron.net/blog/deploying-django-mod-wsgi-virtualenv/