django-json-settings

django-json-settings is a small Django application that allows you to provide specific local settings in JSON format, generally for production or other non-developer environments (although it could also be used for settings that vary on a per-developer basis).

This presumes you are deploying into a virtualenv, and it imposes a few assumptions about how that virtualenv should be structured, based on standard UNIX naming.

What it does

When deployed in a virtualenv, and called from your settings.py, django-json-settings looks for a file called:

<sys.prefix>/etc/settings.json

This file is then read and it's contents placed into the standard django settings.

You do this by putting:

from json_settings import *

In your settings.py at an appropriate point.

Additional magic settings

In addition to this, django-json-settings will set three new values (if they aren't already defined):

VAR_DIRECTORY to <sys.prefix>/var
STATIC_ROOT to <VAR_DIRECTORY>/static
MEDIA_ROOT to <VAR_DIRECTORY>/media

These are quite useful things to have configured.

How to use it

Obviously first you should add a dependency to your setup.py on django-json-settings, and then install it.

Then add a call to "from json_settings import *" in your settings.py at the right point. Generally you should structure your settings.py so that you have 3 types of setting:

1. Things that are definitely going to need to be set in production. For example, ADMINS, ALLOWED_HOSTS, SECRET_KEY, STATIC_ROOT
2. Things you might want to change in production, but might want to leave alone, for example LOGGING
3. Things you don't want to change in production, ever. For example, MIDDLEWARE_CLASSES

You should put the json_settings import statement after all of those in 2, but before those in 3.

This means whoever is deploying the software gets lots of choice about the environment, but can't accidentally hose things that are really core application configuration.

Here is an example settings.py:

import sys
import os

DEBUG = True
ADMINS = (
)

ALLOWED_HOSTS = []
TIME_ZONE = 'Europe/London'

SECRET_KEY = '*ivd!%8j-=7r36ng^)rmeto(wj)#9)ylzd_hhrzv#x%+a)gs8x'

SESSION_COOKIE_AGE = 3600

LANGUAGE_CODE = 'en-us'

STATIC_ROOT = 'static/'
MEDIA_ROOT = 'media/'

from json_settings import *

TEMPLATE_DEBUG = DEBUG
MANAGERS = ADMINS

SITE_ID = 1

...

Testing local settings

You can use a different settings file by setting an environment variable JSON_SETTINGS:

JSON_SETTINGS=example.json ./manage.py runserver

If you want to try some settings out.

Error Handling

If the settings.json file is invalid then your application will terminate with an error.

If the file is absent then this is only an error if it was provided using the JSON_SETTINGS environment variable. A missing file is otherwise assumed to be ok (so you can put development defaults in your settings.py and not have a local settings file at all).