Django : Do not forget Do Not Track

If you (fooly) Sail© on the Web® without Ghostery™, this website is currently tracking you. Sad news, but there are indeed 3 widgets (Disqus, Piwik and Twitter on the About page) that may collect data about your presence here.

The Do-Not-Track initiative consists in avoiding user tracking, using an HTTP header, sent by the browser. It is a voluntary process, and we should honour it when we can ! [1].

Here is a quick way of respecting privacy in your Django websites.

We use a context processor to spread the word accross all templates.

# context_processors.py
def donottrack(request):
    return {
        'donottrack': request.META.get('HTTP_DNT') == '1'
    }

You can then disable spying widgets and tools, such as Google Analytics...

{% load ganalytics %}

{% if not donottrack %}
  {% ganalytics %}
{% endif %}

...or share buttons !

<ul class="social-buttons cf">
  {% if donottrack %}
    <li><a href="http://wikipedia.org/wiki/Do_Not_Track">{% trans "Do-Not-Track is set." %}</a></li>
  {% else %}
    <li><a href="//twitter.com/share" class="socialite twitter-share" data-text="{{ TITLE }} {{ URL }}">
        <span class="vhidden">{% trans "Twitter" %}</span></a>
    </li>
  {% endif %}
</ul>

We now need a middleware to add vary headers (for cache control), since content depends on this header.

# middleware.py
from django.utils.cache import patch_vary_headers


class DoNotTrackMiddleware(object):
    def process_response(self, request, response):
        patch_vary_headers(response, ('DNT',))
        return response

Add those to your TEMPLATE_CONTEXT_PROCESSORS and MIDDLEWARE_CLASSES settings and you're done.

Update : There are reusable apps doing just that if you prefer : django-dnt, django-donottrack.

#django, #mozilla, #privacy - Posted in the Dev category

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