__init__.py

# Conf init file

import os
import importlib

ENVIRONMENT_VARIABLE ='APP_SETTINGS'

SETTINGS_MODULE = os.environ.get(ENVIRONMENT_VARIABLE)

if not SETTINGS_MODULE:
    raise RuntimeError("%s needs to be set!" % SETTINGS_MODULE)

settings = importlib.import_module(SETTINGS_MODULE)

local.py

import os
from foobar.conf.base import *

DEBUG = True