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12factor config support for Django

Project Description

What is it?

Django is an awesome Python web framework.

The Twelve-Factor App” is an awesome methodology for building SaaS apps.

dj12 makes Django more 12factor-y. Right now, this focuses on the Config - “Store config in the environment”; Heroku users with addons will be particularly familiar with this.

Still not sure of the benefits? Check out “Twelve-Factor Config: Misunderstandings and Advice”.


pip install dj12

At the end of your, add:

from dj12.config import *

And it’s done, your app supports 12factor config!

Still, you may want to delete obsolete config variables:

  • EMAIL_*

We also provide modern defaults for these variables, so you don’t need to set them yourself:

  • USE_I18N = True
  • USE_L10N = True
  • USE_TZ = True


Default settings are optimized for the development environments, and for doing nothing if you don’t use that particular Django feature. Change them only when you need to do so - for example, set DATABASE_URL when you need database persistency on production, and CACHE_URL when you need out-of-process cache on production.

SECRET_KEY (required when DEBUG=off)


A secret key for a particular environment. This is used to provide cryptographic signing, and should be set to a unique, unpredictable value.

This is the only required setting, because it’s a security issue to run without SECRET_KEY on production.

Keep this value secret.

Running Django with a known SECRET_KEY defeats many of Django’s security protections, and can lead to privilege escalation and remote code execution vulnerabilities.

Read more at Django: SECRET_KEY.


Type:comma separated list
Default value:localhost

A list of strings representing the host/domain names that this Django site can serve. This is a security measure to prevent HTTP Host header attacks, which are possible even under many seemingly-safe web server configurations.

Read more at Django: ALLOWED_HOSTS.


Default value:off

A boolean that turns on/off debug mode.

Never deploy a site into production with DEBUG turned on.

Did you catch that? NEVER deploy a site into production with DEBUG turned on.

Read more at Django: DEBUG.


Default value:sqlite:///db.sqlite3 (db.sqlite3 file in the current working directory)

This is the URL to your database.

Note: This configures the Django’s “default” database; you may also use WHATEVER_*DATABASE_URL to configure “*whatever” database.

Read more at dj-database-url.


Default value:locmem:// (memory)

This is the URL to your caching system.

Note: This configures the Django’s “default” cache; you may also use WHATEVER_*CACHE_URL to configure “*whatever” cache.

Read more at django-cache-url.


Default value:console:// (print emails to the console)

This is the URL to your email sending system.

Read more at dj-email-url.


Type:email address
Default value:webmaster@localhost

Default email address to use for emails sent to users.

Read more at Django: DEFAULT_FROM_EMAIL.


Default value:off

Turn this on if your app is behind a reverse proxy that sends X-Forwarded-Proto header. This controls the behavior of the request object’s is_secure() method.

Warning: You will probably open security holes in your site if you set this without knowing what you’re doing. And if you fail to set it when you should. Seriously.

Read more at Django: SECURE_PROXY_SSL_HEADER.


Default value:en-us

Default language for the environment. Supports both standard language ID format, and UNIX $LANG format.

It serves two purposes:

  • If the locale middleware isn’t in use, it decides which translation is served to all users.
  • If the locale middleware is active, it provides a fallback language in case the user’s preferred language can’t be determined or is not supported by the website. It also provides the fallback translation when a translation for a given literal doesn’t exist for the user’s preferred language.

Read more at Django: LANGUAGE_CODE.


Default value:UTC

A string representing the time zone for this environment. See the list of time zones.

Read more at Django: TIME_ZONE.



Sentry DSN - use this if you’re using Sentry to monitor your app.

Note that you still have to add Raven app to INSTALLED_APPS, as we don’t want to always require it, and modifying the list of installed apps based on the environment variables is a bad idea. However, you may safely run Django with Raven installed but RAVEN_URL unset.

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