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Difficulty: Moderate
Time: varies
Last Updated: 23rd September 2010
Applies to: *NIX

Phusion passenger is a fast and robust solution for serving python web apps, particularly those using the Django framework.

To start, it is assumed you have a suitably configured *NIX base system. This has been tried using Gentoo and Ubuntu.

The next thing to do is to install apache2. NGINX is also supported, however we will be using apache. It should also be possible to use lighttpd, however, there is no official support for such a configuration.

Passenger prefers to use the worker mpm, however if you wish to run PHP apps on the same server instance, you need to use the prefork mpm.

Next, ensure that you install the django framework (your distribution probably has it available as a package, try “apt-get install python-django” or “zypper in python-django“). Also required is

The next step is to configure a VHost (or the default host if you will only be using a single app) and ensure that it can successfully serve static html files without issue.

Next, you need to add a line to the site config file, “PassengerAppRoot“. This tells passenger where to look for the python application you want to serve on that domain.

Once this is done, deploy your django app into /var/www, or wherever you specified the passenger app root to be. If you are writing an app from scratch, then the command is “django-admin startproject <projectname>“.

Finally, there is one more step you need to do before passenger will serve your app.

You need to create a passenger_wsgi.py file in the passenger root folder. This file looks like this:

Once this is done, passenger should now start serving your apps.

One final note is that passenger does not cope very well with fatal errors. There tend to not be written to the browser or logs, making them hard to pin down.

To get around this, you can install python-paste (try “apt-get install python-paste“), and use this to catch any fatal errors.

To enable this, you need to make a small change to passenger_wsgi.py:

If a fatal exception now occurs, it will have a stack trace recorded and emitted to the client. This is useful for testing, but should be used with care in a production environment, as it may expose information such as passwords if not configured correctly.