Django Staging Server: Apache Configuration

In this post, I'd like to talk a little about how my staging server (called Kaylee, after the character from Firefly), is configured to run the multiple Django projects that I have on the go. A lot of the other articles I have read on this subject use mod_python but my server is configured to use WSGI, so that's what I will be going over in this post.

Beginnings

Firstly, I use virtualenv to keep the Python environments for the different projects separate, but that's a topic in itself. This isn't a requirement, but it helps if you have dependencies that you don't want installed system-wide, or projects that use different versions of a particular package.

You can read more about virtualenv and Django here.

The directory structure for my webapps directory (which lives inside /home/) looks something like this:

webapps/
|-- apache
|   |-- coral.conf
|   |-- coral.wsgi
|   |-- myuni.conf
|   `-- myuni.wsgi
|-- coral
|   |-- env
|   `-- repository
|-- myuni
|   |-- env
|   `-- repository

The two projects shown here are Coral Issue Tracker and MyUni. The directory for each project contains the virtual env for that project, and the repository. Alongside the project folders is a directory called apache, which holds two files for each project: the WSGI file (<project-name>.wsgi) and the Apache configuration file (<project-name>.conf).

Apache Configuration

Then, in the main Apache configuration, I use a directive that includes all these files automatically:

Include    /home/webapps/apache/*.conf

The individual project configuration files then contain a set of simple directives almost straight from the Django deployment documentation. For example, the MyUni configuration looks like this:

WSGIScriptAlias  /myuni        /home/webapps/apache/myuni.wsgi
Alias            /myuni/docs   /home/webapps/myuni/repository/docs/_build/html
Alias            /myuni/media  /home/webapps/myuni/repository/myuni/static

WSGI Files

The WSGI files are also pretty simple, though there are a couple of things worth explaining. Here is the WSGI file for the MyUni project:

import os
import sys
import site
 
os.environ['PYTHON_EGG_CACHE'] = '/tmp/myuni/egg_cache'
 
root_dir = '/home/webapps/myuni/env'
 
# with mod_wsgi >= 2.4, this line will add this path in front of the python path
site.addsitedir(os.path.join(root_dir, 'lib/python2.6/site-packages'))
 
sys.path.append('/home/webapps/myuni/repository')
 
os.environ['DJANGO_SETTINGS_MODULE'] = 'myuni.settings'
 
import django.core.handlers.wsgi
 
application = django.core.handlers.wsgi.WSGIHandler()

The site.addsitedir() call in the WSGI file adds the library path in the virtual environment to the python path, by inspecting it to find all the packages that are installed. I then append the path to the project's repository to the path also, as is standard practice in this type of deployment.

The only other thing worth mentioning here, is the PYTHON_EGG_CACHE variable that I add to the environment. This is required if you are using Python modules that are packaged up as eggs, so that Apache can uncompress them in a directory to which it can write (/tmp/ on Ubuntu is 777 by default). If you are not using eggs, you can skip this line out altogether. Alternatively, you can uncompress the eggs first:

$ unzip [package].egg

You can read more about this issue, and the workaround, here.

Summary

That's pretty much all there is to it. This setup also makes it pretty easy to deploy new versions of my projects, for which I have started using Fabric. I'll save that for another post though.

If you do things differently, then I'd love to hear about how - so please leave a comment!

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