settings.py

import environ
import os
root = environ.Path(__file__) - 2 # two folders back (/a/b/ - 2 = /)
env = environ.Env(DEBUG=(bool, False),) # set default values and casting
GOOGLE_ANALYTICS_ID=env('GOOGLE_ANALYTICS_ID')

SITE_DOMAIN = env('SITE_DOMAIN') 
SITE_ROOT = root()

DEBUG = env('DEBUG') # False if not in os.environ

DATABASES = {
    'default': env.db(), # Raises ImproperlyConfigured exception if DATABASE_URL not in os.environ
}

public_root = root.path('./public/')

MEDIA_ROOT = public_root('media')
MEDIA_URL = '/media/'

STATIC_ROOT = public_root('static')
STATIC_URL = '/static/'

AWS_ACCESS_KEY_ID = env('AWS_ACCESS_KEY_ID')
AWS_SECRET_ACCESS_KEY = env('AWS_SECRET_ACCESS_KEY')

...