django-cachekiller

django-cachekiller is a small add-on for Django that adds the cdnstatic template tag which adds a 'cache busting' dynamic query string appended to the file paths. This tag functions identically to the standard {% static ... %} template tag. This is designed to work with CDNs that cache by complete URI including the query string so when you push a change the CDNs are automatically refreshed without having to wait for TTLs to expire. Internally we use this with django-distill, a static site generator for Django to work with static sites with heavy caching on images behind CloudFlare, cachefly and other CDNs:

https://github.com/meeb/django-distill

Under the hood, this module just chains the request to the existing static tag to be widely compatible.

Installation

Install from pip:

$ pip install django-cachekiller

Add django_cachekiller to your INSTALLED_APPS in your settings.py:

INSTALLED_APPS = [
    # ... other apps here ...
    'django_cachekiller',
]

That's it.

Usage

Load the new module at the top of your templates:

{% load cdnstaticfiles %}

Then use the new tag in the template exactly as you would use the static tag:

{% cdnstatic 'some/image.jpg' %}

This renders as (assuming settings.STATIC_URL is set to /static/):

/static/some/image.jpg?tag=[random tag]

[random tag] is either the truncated mercurial or git commit reference if it is available, otherwise it will be the current date in YYYYMMDDHHMMSS format. If there are existing query string parameters then the tag is intelligently appended. The cdnstatic tag will not break the existing URL.

Additionally, if you need to just access the [random tag] for some other use without the automatic URL rewriting you can use the following:

<a href="/someurl.html?tag={% cdntag %}">link</a>

This can be used in conjunction with other URL wrapping tags for combatability where chaining tags is difficult, for example:

<link rel="stylesheet" href="{% sass_src 'file.scss' %}?tag={% cdntag %}">

Contributing

All properly formatted and sensible pull requests, issues and comments are welcome.