id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
22567	FileSystemStorage.modified_time() is not timezone aware	James Aylett	nobody	"I'm using the S3BotoStorage backend from django_storages, and collecstatic does not always upload new copies of static files. S3BotoStorage modified times come back in UTC (verified against Amazon's S3 console):

{{{
from django.contrib.staticfiles import finders, storage
f = list(finders.get_finders())
pss = list(f[0].list([]))
ps = pss[-1]

from django.contrib.staticfiles.storage import staticfiles_storage as sf
sf._setup()
tlm = sf.modified_time(ps[0])
slm = ps[1].modified_time(ps[0])
print tlm
print slm
}}}

gives:

{{{
2014-05-02 10:25:33
2014-05-02 09:57:57
}}}

However the local machine is in PDT (it's a Heroku dyno on an Amazon west coast instance somewhere):

{{{
>>> import os
>>> os.system('ls -l static/css')
total 8
-rw------- 1 u29977 29977 5838 2014-05-02 09:57 base.css
0
>>> os.system('date')
Fri May  2 11:39:28 PDT 2014
0
}}}

So the correct modified time in UTC for the local `static/css/base.css` is 2014-05-02 16:57:57, or several hours *after* the target file on S3 was last modified.

Because `FileSystemStorage` isn't timezone aware, the comparison for ""newer than target"" in `collectstatic` fails, and only updates that are more than seven hours (currently) after the previous successful update actually get deployed.

I'm pretty sure the actual problem is that `datetime.datetime.fromtimestamp` converts to localtime but returns a naive object. I *believe* that forcing it into UTC by using `…fromtimestamp(since_epoch, django.utils.timezone.utc)` would be appropriate (in the methods at the end of `django/core/files/storage.py`), but timezones are fiddly things and I don't even have the brainpower right now to figure out how to write a simple test for this that can work no matter which underlying TZ the machine is configured for."	Bug	closed	File uploads/storage	1.6	Normal	invalid		denis.cornehl@…	Unreviewed	0	0	0	0	0	0