AttributeError: 'Settings' object has no attribute 'ROOT_URLCONF' on Heroku

Question

I am getting this error when I deploy to Heroku:

2014-05-07T11:50:06.927955+00:00 heroku[router]: at=info method=GET path=/favicon.ico host=staging.mysite.com request_id=eead056c-f89d-4fcd-b282-71a023631a71 fwd="80.237.234.148" dyno=web.1 connect=1ms service=4ms status=500 bytes=238
2014-05-07T11:50:06.925723+00:00 app[web.1]: 2014-05-07 06:50:06 [7] [ERROR] Error handling request
2014-05-07T11:50:06.925732+00:00 app[web.1]: Traceback (most recent call last):
2014-05-07T11:50:06.925746+00:00 app[web.1]:     urlconf = settings.ROOT_URLCONF
2014-05-07T11:50:06.925735+00:00 app[web.1]:   File "/app/.heroku/python/lib/python2.7/site-packages/gunicorn/workers/sync.py", line 126, in handle_request
2014-05-07T11:50:06.925738+00:00 app[web.1]:     respiter = self.wsgi(environ, resp.start_response)
2014-05-07T11:50:06.925740+00:00 app[web.1]:   File "/app/.heroku/python/lib/python2.7/site-packages/django/core/handlers/wsgi.py", line 241, in __call__
2014-05-07T11:50:06.925742+00:00 app[web.1]:     response = self.get_response(request)
2014-05-07T11:50:06.925744+00:00 app[web.1]:   File "/app/.heroku/python/lib/python2.7/site-packages/django/core/handlers/base.py", line 82, in get_response
2014-05-07T11:50:06.925751+00:00 app[web.1]:     return func(self._wrapped, *args)
2014-05-07T11:50:06.925749+00:00 app[web.1]:   File "/app/.heroku/python/lib/python2.7/site-packages/django/utils/functional.py", line 185, in inner
2014-05-07T11:50:06.925753+00:00 app[web.1]: AttributeError: 'Settings' object has no attribute 'ROOT_URLCONF'

Locally it works fine, and in the remote bash shell, it seems that django can access ROOT_URLCONF, as I am running:

~ $ python manage.py shell
Python 2.7.4 (default, Apr 6 2013, 22:14:13)
In [2]: from django.conf import settings
In [3]: settings.ROOT_URLCONF
Out[3]: 'urls'

The settings file therefore seems accessible to manage.py and includes the correct ROOT_URLCONF variable.

I have tried very many configurations with no luck. Any ideas?

Here are my current manage.py and settings configurations (env variable ENV is set to staging here):

# manage.py

#!/usr/bin/env python
import os
import sys

environment = os.environ['ENV']

if __name__ == "__main__":
    os.environ.setdefault("DJANGO_SETTINGS_MODULE", 'main.settings.' + environment)

    from django.core.management import execute_from_command_line
    execute_from_command_line(sys.argv)

settings/ folder contains an empty __init__.py and:

# staging.py

from .base import *

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django_facebook.auth_backends.FacebookBackend',
    'fandjango.middleware.FacebookMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    # 'debug_toolbar.middleware.DebugToolbarMiddleware',
    # Uncomment the next line for simple clickjacking protection:
    # 'django.middleware.clickjacking.XFrameOptionsMiddleware',
)

INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.sites',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'south',
    'crewcal',
    'django_extensions',
    'registration',
    'django_facebook',
    'fandjango',
    'django.contrib.humanize',
    'storages',
    'datetimewidget',
    'postman',
    'notification',
    # 'raven.contrib.django.raven_compat',
    # Uncomment the next line to enable the admin:
    'django.contrib.admin',
    # Uncomment the next line to enable admin documentation:
    # 'django.contrib.admindocs',
)



# base.py

ENV = 'DEVELOPMENT'

import os
import sys

MAIN_APP_DIR = os.path.dirname(__file__)
PROJECT_NAME = MAIN_APP_DIR.split('/')[-1]
project_root = lambda f: os.path.abspath(os.path.join(MAIN_APP_DIR, '../../', f))


PROJECT_ROOT = os.path.abspath(os.path.dirname(__file__))
PROJECT_DIR = os.path.join(PROJECT_ROOT,'../../crewcal')

WEB_ROOT = project_root('webroot')


sys.path.insert(0, os.path.join(MAIN_APP_DIR, '../'))
sys.path.insert(0, MAIN_APP_DIR)

dev = 'DEVELOPMENT'

DEBUG = (ENV is dev)
TEMPLATE_DEBUG = DEBUG

TESTING = 'test' in sys.argv

ADMINS = (
    ('Me', '[email protected]'),
)

MANAGERS = ADMINS

DATABASE_CONFIGS = {
    'DEVELOPMENT': {
        'default': {
            'ENGINE': 'django.db.backends.postgresql_psycopg2', # Add 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'.
            'NAME': 'ssc',                      # Or path to database file if using sqlite3.
            'USER': 'postgres',                      # Not used with sqlite3.
            'PASSWORD': 'xxx',                  # Not used with sqlite3.
            'HOST': '',                      # Set to empty string for localhost. Not used with sqlite3.
            'PORT': '',                      # Set to empty string for default. Not used with sqlite3.
        }
    },
}

DATABASES = DATABASE_CONFIGS[ENV]

SITE_ID = 1

# If you set this to False, Django will make some optimizations so as not
# to load the internationalization machinery.
USE_I18N = False

# If you set this to False, Django will not format dates, numbers and
# calendars according to the current locale.
USE_L10N = True

gettext = lambda s: s
LANGUAGES = (('en', gettext('English')),)

MEDIA_ROOT = os.path.join(WEB_ROOT, 'media')
MEDIA_URL = '/media/'

STATIC_ROOT = os.path.join(PROJECT_DIR, 'static')

AWS_ACCESS_KEY_ID = 'SECRET'
AWS_SECRET_ACCESS_KEY = 'SECRET'
AWS_STORAGE_BUCKET_NAME = 'vvv'

# URL prefix for static files.
# Example: "http://media.lawrence.com/static/"
try:
    if os.environ['ENV'] == 'staging' or 'production':
        STATIC_URL = 'https://s3-eu-west-1.amazonaws.com/vvv/'
except:
    STATIC_URL = '../mysite/static/'

# Additional locations of static files
STATICFILES_DIRS = (
    # Put strings here, like "/home/html/static" or "C:/www/django/static".
    # Always use forward slashes, even on Windows.
    # Don't forget to use absolute paths, not relative paths.
)

# List of finder classes that know how to find static files in
# various locations.
STATICFILES_FINDERS = (
    'django.contrib.staticfiles.finders.FileSystemFinder',
    'django.contrib.staticfiles.finders.AppDirectoriesFinder',
#    'django.contrib.staticfiles.finders.DefaultStorageFinder',
)

# Make this unique, and don't share it with anybody.
SECRET_KEY = os.environ['SECRET_KEY']

# List of callables that know how to import templates from various sources.
TEMPLATE_LOADERS = (
    'django.template.loaders.filesystem.Loader',
    'django.template.loaders.app_directories.Loader',
#     'django.template.loaders.eggs.Loader',
)

try:
    if os.environ['ENV'] == 'staging' or 'production':
        EMAIL_BACKEND = 'django.core.mail.backends.smtp.EmailBackend'
except:
    EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'

EMAIL_FILE_PATH = (
    #os.path.join(SITE_ROOT, '/app-email-messages') # change this to a proper location)
)
ACCOUNT_ACTIVATION_DAYS = 7
EMAIL_HOST = 'smtp.gmail.com'
EMAIL_HOST_USER = '[email protected]'
EMAIL_HOST_PASSWORD = os.environ['EMAIL_HOST_PASSWORD']
EMAIL_PORT = 587
EMAIL_USE_TLS = True

POSTMAN_AUTO_MODERATE_AS = True

ROOT_URLCONF = 'main.urls'

# Python dotted path to the WSGI application used by Django's runserver.
WSGI_APPLICATION = 'wsgi.application'


PROJECT_PATH = os.path.realpath(os.path.dirname(os.path.dirname(__file__)))

TEMPLATE_DIRS = (
    os.path.join(PROJECT_PATH, 'templates/'),
    # Put strings here, like "/home/html/django_templates" or "C:/www/django/templates".
    # Always use forward slashes, even on Windows.
    # Don't forget to use absolute paths, not relative paths.
)

STATICFILES_STORAGE = 'storages.backends.s3boto.S3BotoStorage'

FACEBOOK_APP_ID = 'app-id'
FACEBOOK_APP_SECRET = os.environ['FACEBOOK_APP_SECRET']

# fandjango settings
FACEBOOK_APPLICATION_ID = 'app-id'
FACEBOOK_APPLICATION_SECRET_KEY = os.environ['FACEBOOK_APP_SECRET']
FACEBOOK_APPLICATION_NAMESPACE = 'me'

try:
    if os.environ['DOMAIN'] == 'crew':
        DOMAIN = 'crew'
        EVENT_PUB_COMMITTED_CRITICAL_MASS = 3
    elif os.environ['DOMAIN'] == 'staging':
        DOMAIN = 'staging'
        EVENT_PUB_COMMITTED_CRITICAL_MASS = 2
except:
    DOMAIN = 'crew'
    EVENT_PUB_COMMITTED_CRITICAL_MASS = 3


try:
    if os.environ['ENV'] == 'staging':
        MAX_PROPOSED_EVENTS = 3
except:
    MAX_PROPOSED_EVENTS = 300

POSTMAN_DISALLOW_ANONYMOUS = True
POSTMAN_AUTO_MODERATE_AS = True


INTERNAL_IPS = ('127.0.0.1',)

LOGIN_URL = '/login'
LOGOUT_URL = '/logout'
LOGIN_REDIRECT_URL = "/user"

AUTH_PROFILE_MODULE = 'me.UserProfile'
AUTHENTICATION_BACKENDS = (
    'crewcal.backends.EmailOrUsernameModelBackend',
    'django.contrib.auth.backends.ModelBackend',
    'django_facebook.auth_backends.FacebookBackend',
    'insensitive.backends.CaseInsensitiveModelBackend'
)

# A sample logging configuration. The only tangible logging
# performed by this configuration is to send an email to
# the site admins on every HTTP 500 error when DEBUG=False.
# See http://docs.djangoproject.com/en/dev/topics/logging for
# more details on how to customize your logging configuration.
LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'filters': {
        'require_debug_false': {
            '()': 'django.utils.log.RequireDebugFalse'
        }
    },
    'handlers': {
        'mail_admins': {
            'level': 'ERROR',
            'filters': ['require_debug_false'],
            'class': 'django.utils.log.AdminEmailHandler'
        }
    },
    'loggers': {
        'django.request': {
            'handlers': ['mail_admins'],
            'level': 'ERROR',
            'propagate': True,
        },
    }
}

TEMPLATE_CONTEXT_PROCESSORS = (
    "django.contrib.auth.context_processors.auth",
    "django.core.context_processors.debug",
    "django.core.context_processors.i18n",
    "django.core.context_processors.media",
    "django.core.context_processors.static",
    "django.core.context_processors.request",
    "django.core.context_processors.tz",
    "django.contrib.messages.context_processors.messages",
    "django_facebook.context_processors.facebook"
)


try:
    if os.environ['ENV'] == 'production':
        DEBUG = False
        ALLOWED_HOSTS = ['me.org.uk',]
        # Parse database configuration from $DATABASE_URL
        import dj_database_url
        DATABASES['default'] =  dj_database_url.config()

        # Honor the 'X-Forwarded-Proto' header for request.is_secure()
        SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')
    if os.environ['ENV'] == 'staging':
        DEBUG = False
        ALLOWED_HOSTS = ['me.org.uk',]
        # Parse database configuration from $DATABASE_URL
        import dj_database_url
        DATABASES['default'] =  dj_database_url.config()

        # Honor the 'X-Forwarded-Proto' header for request.is_secure()
        SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')
except:
    pass

Solution

The problem occurred because I have switched from a single settings file to a settings package, updated the references in manage.py, so it works locally, but didn't reflect that in wsgi.py which is what configures the server on Heroku.

wsgi.py now sets environment-specific settings:

os.environ["DJANGO_SETTINGS_MODULE"] = "main.settings." + os.environ["ENV"]