[python] How to manage local vs production settings in Django?

I found the responses here very helpful. (Has this been more definitively solved? The last response was a year ago.) After considering all the approaches listed, I came up with a solution that I didn't see listed here.

My criteria were:

  • Everything should be in source control. I don't like fiddly bits lying around.
  • Ideally, keep settings in one file. I forget things if I'm not looking right at them :)
  • No manual edits to deploy. Should be able to test/push/deploy with a single fabric command.
  • Avoid leaking development settings into production.
  • Keep as close as possible to "standard" (*cough*) Django layout as possible.

I thought switching on the host machine made some sense, but then figured the real issue here is different settings for different environments, and had an aha moment. I put this code at the end of my settings.py file:

try:
    os.environ['DJANGO_DEVELOPMENT_SERVER'] # throws error if unset
    DEBUG = True
    TEMPLATE_DEBUG = True
    # This is naive but possible. Could also redeclare full app set to control ordering. 
    # Note that it requires a list rather than the generated tuple.
    INSTALLED_APPS.extend([
        'debug_toolbar',
        'django_nose',
    ])
    # Production database settings, alternate static/media paths, etc...
except KeyError: 
    print 'DJANGO_DEVELOPMENT_SERVER environment var not set; using production settings'

This way, the app defaults to production settings, which means you are explicitly "whitelisting" your development environment. It is much safer to forget to set the environment variable locally than if it were the other way around and you forgot to set something in production and let some dev settings be used.

When developing locally, either from the shell or in a .bash_profile or wherever:

$ export DJANGO_DEVELOPMENT_SERVER=yep

(Or if you're developing on Windows, set via the Control Panel or whatever its called these days... Windows always made it so obscure that you could set environment variables.)

With this approach, the dev settings are all in one (standard) place, and simply override the production ones where needed. Any mucking around with development settings should be completely safe to commit to source control with no impact on production.

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