Django + mod_wsgi. Set OS environment variable from Apache's SetEnv

Question

I need to split Django's development and production settings. I decided that if USKOVTASK_PROD variable is set, then app should use production settings. I read this article and tried to do it.

My snippets:

/etc/apache2/sites-enabled/uskovtask.conf:

<VirtualHost *:80>

ServerName uskovtask.*.com
ServerAlias uskovtask.*.com
DocumentRoot /mnt/ebs/uskovtask


Alias /static /mnt/ebs/uskovtask/static/
<Directory /mnt/ebs/uskovtask/static>
    Require all granted
</Directory>

#WSGIPythonPath /mnt/ebs/uskovtask
WSGIDaemonProcess uskovtask.*.com python-path=/mnt/ebs/uskovtask:/usr/lib/python2.7/site-packages
WSGIProcessGroup uskovtask.*.com
WSGIScriptAlias / /mnt/ebs/uskovtask/uskovtask/wsgi.py
SetEnv USKOVTASK_PROD 1


<Directory /mnt/ebs/uskovtask/uskovtask>
<Files wsgi.py>
    Require all granted
</Files>
</Directory>

</VirtualHost>

wsgi.py:

import os
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "uskovtask.settings")

from django.core.wsgi import get_wsgi_application

_application = get_wsgi_application()

def application(environ, start_response):
    if 'USKOVTASK_PROD' in environ:
        os.environ.setdefault('USKOVTASK_PROD', environ['USKOVTASK_PROD'])
    return _application(environ, start_response)

settings.py's part:

import os

if 'USKOVTASK_PROD' in os.environ:
    from settings_prod import *
else:
    from settings_dev import *

But it always imports settings_dev's settings. Why?

Answer 1

This is related to question Access Apache SetEnv variable from Django wsgi.py file

You need to inherit WSGIHandler as the answer says.

As Graham Dumpleton explains in the second answer,

That all said, the blog post you mention will not usually help. This is because it is using the nasty trick of setting the process environment variables on each request based on the per request WSGI environ settings set using SetEnv in Apache. This can cause various issues in a multi threading configuration if the values of the environment variables can differ based on URL context. For the case of Django, it isn't helpful because the Django settings module would normally be imported before any requests had been handled, which means that the environment variables would not be available at the time required.

and I think this is what is happening in your case.

Answer 2

I solved this problem by changing wsgi.py to this:

from django.core.handlers.wsgi import WSGIHandler
import django
import os

class WSGIEnvironment(WSGIHandler):

    def __call__(self, environ, start_response):

        os.environ['USKOVTASK_PROD'] = environ['USKOVTASK_PROD']
        os.environ.setdefault("DJANGO_SETTINGS_MODULE", "uskovtask.settings")
        django.setup()
        return super(WSGIEnvironment, self).__call__(environ, start_response)

application = WSGIEnvironment()