Django Friends Meetup, 2015-02-05

A short tale about MEDIA_URLs

... or testing with settings override

Florian Demmer (@fdemmer)
www.floriandemmer.com

backstory

backstory

http://en.wikipedia.org/wiki/POODLE

backstory

CVE-2014-3566 Advisory

We have disabled SSLv3 for all customers
who use SSL with the default CloudFront
domain name (*.cloudfront.net).

http://aws.amazon.com/security/security-bulletins/CVE-2014-3566-advisory/

backstory

backstory

solution

don't use HTTPS for SmartTV API

... but still use it on web frontend.

... and also better use protocol relative URLs.
(but not in API)

CDN_URL = '//da2s5d7fli.cloudfront.net'

solution

def rewrite_protocol(url, replacement=None):
    replacement = replacement or settings.STV_API_MEDIA_PROTOCOL
    if replacement:
        parts = urlparse.urlsplit(url)
        # only rewrite protocol if host is available
        if parts[1]:
            return urlparse.urlunsplit((replacement,) + parts[1:])
    return url

testing

class APITest(testcases.TestCase):
    def test_http_location(self):
        CDN_URL = 'http://cloudfront.com'
        MEDIA_URL = '/media/'
        with self.settings(MEDIA_URL=CDN_URL+MEDIA_URL):
            ...

the settings override

happens at runtime

"ImageFields" use storage to generate URLs

should affect the "DefaultStorage" all "ImageFields" use

but "DefaultStorage" loads setting at init

how about a signal on setting change?

the signal

https://code.djangoproject.com/ticket/17744

@receiver(setting_changed)
def file_storage_changed(**kwargs):
    if kwargs['setting'] in ('MEDIA_ROOT', 'DEFAULT_FILE_STORAGE'):
        from django.core.files.storage import default_storage
        default_storage._wrapped = empty

... no trigger on MEDIA_URL change.

and other storages?

eg. easy_thumbnails

quick solution in test class:

def _nuke_storage_instances(self):
    # reset image storages to reload settings
    from django.core.files.storage import default_storage
    default_storage._wrapped = empty

    from easy_thumbnails.storage import thumbnail_default_storage
    thumbnail_default_storage._wrapped = empty

all the things

https://code.djangoproject.com/ticket/17744

https://github.com/django/django/commit/a24ffa52d02998f5082fbc5a461ccdc8004db4a6