I am working on a project which uses ThreadedComments in a couple of apps
(Mezzanine Blog and a discussion forum). All was working fine in the
development and production environment but from one day to the next posting
a comment raised an Internal Server Error (500).
My setup: Mezzanine 4.01, Django 1.8.5, Python 2.7.6. The production
environment is a Ubuntu 14.04 server, Apache webserver. Mezzanine is
deployed using mod_wsgi-express. Mezzanine is set up using "German" as
language.
The error log created by the server gives me the following:
Traceback (most recent call last):
[Thu Dec 17 21:08:23.317452 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] File
"/home/chris/IT/Portal/veportal/local/lib/python2.7/site-packages/mod_wsgi-4.4.15-py2.7-linux-x86_64.egg/mod_wsgi/server/__init__.py"
, line 1346, in handle_request
[Thu Dec 17 21:08:23.317902 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] return self.application(
environ, start_response)
[Thu Dec 17 21:08:23.317919 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] File
"/home/chris/IT/Portal/veportal/local/lib/python2.7/site-packages/django/core/handlers/wsgi.py"
, line 195, in __call__
[Thu Dec 17 21:08:23.317982 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] response_headers.append((str
('Set-Cookie'), str(c.output(header=''))))
[Thu Dec 17 21:08:23.317993 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] File
"/usr/lib/python2.7/Cookie.py", line 466, in output
[Thu Dec 17 21:08:23.318106 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] return "%s %s" % ( header,
self.OutputString(attrs) )
[Thu Dec 17 21:08:23.318116 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] File
"/usr/lib/python2.7/Cookie.py", line 514, in OutputString
[Thu Dec 17 21:08:23.318128 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] return _semispacejoin(result
)
[Thu Dec 17 21:08:23.318143 2015] [wsgi:error] [pid 30806:tid
140269963933440] [remote 95.90.251.8:24357] UnicodeDecodeError: 'ascii'
codec can't decode byte 0xc3 in position 16: ordinal not in range(128)
After some digging I found that this error was caused by the "set_cookie"
method in mezzanine.utils.views. When creating the "expires" date the
locale de_DE, utf-8 is used by strftime and the month of March in German
contains a non ASCII character (i.e. "Umlaut"). Therefore the error only
pops up if a cookie with expiry "March" is set.
For testing purposes I tried running my project using the Django
development server in the production environment - strangely enough I did
NOT get the error there.
As a quick fix I temporarily set the locale back to en_US, utf-8 before
setting the cookie using this
<http://stackoverflow.com/questions/18593661/how-do-i-strftime-a-date-object-in-a-different-locale>
approach; i.e. mezzanine.utils.views like so:
# This is a hack to avoid unicode decode errors caused on the production
server
# by a german expiry date
import locale
import threading
from contextlib import contextmanager
LOCALE_LOCK = threading.Lock()
@contextmanager
def setlocale(name):
with LOCALE_LOCK:
saved = locale.setlocale(locale.LC_ALL)
try:
yield locale.setlocale(locale.LC_ALL, name)
finally:
locale.setlocale(locale.LC_ALL, saved)
# End of hack
def set_cookie(response, name, value, expiry_seconds=None, secure=False):
"""
Set cookie wrapper that allows number of seconds to be given as the
expiry time, and ensures values are correctly encoded.
"""
if expiry_seconds is None:
expiry_seconds = 90 * 24 * 60 * 60 # Default to 90 days.
# Set back locale to avoid UnicodeDecodeError
with setlocale(('en', 'utf-8')):
expires = datetime.strftime(datetime.utcnow() +
timedelta(seconds=expiry_seconds),
"%a, %d-%b-%Y %H:%M:%S GMT")
# Django doesn't seem to support unicode cookie keys correctly on
# Python 2. Work around by encoding it. See
# https://code.djangoproject.com/ticket/19802
try:
response.set_cookie(name, value, expires=expires, secure=secure)
except (KeyError, TypeError):
response.set_cookie(name.encode('utf-8'), value, expires=expires,
secure=secure)
Although things seem to be working now I do not think fiddling with core
code is a good idea. I am not even sure whether this is really a Mezzanine
issue or whether it has something todo with Apache, mod_wsgi or an issue
with the setup of the production server as such.
Any thoughts welcome.
Regards
Chris
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