get_env_variable.py

# settings/base.py
import os

# Normally you should not import ANYTHING from Django directly
# into your settings, but ImproperlyConfigured is an exception.
from django.core.exceptions import ImproperlyConfigured
def get_env_variable(var_name):
    """ Get the environment variable or return exception """
    try:
        return os.environ[var_name]
    except KeyError:
        error_msg = "Set the %s environment variable" % var_name
        raise ImproperlyConfigured(error_msg)

Thank you, this was very helpful.