Django get settings in template

settings.py

import re

from django import template
from django.conf import settings

register = template.Library()

ALLOWABLE_VALUES = ("CONSTANT_NAME_1", "CONSTANT_NAME_2", "template_\w*")


@register.simple_tag
def settings_value(name):
    """Provide settings values to the templates.

    Name of the value have to be in white list on this module called ALLOWABLE_VALUES.

    Inspired by:
    http://stackoverflow.com/a/21593607/2629036
    http://stackoverflow.com/a/3040797/2629036
    """
    regexes = '(?:%s)' % '|'.join(ALLOWABLE_VALUES)
    if re.match(regexes, name):
        return getattr(settings, name, '')
    return ''