Django Theme Switcher that does not use Django Sites and doesn't use Thread.local

loader.py

from django.core.exceptions import SuspiciousFileOperation
from django.template import Origin
from django.template.loaders.filesystem import Loader
from django.conf import settings
from django.utils._os import safe_join


class ThemeLoader(Loader):
    themes = [theme.get('theme') for theme in settings.SITE_CONFIGS.values()]
    current_theme = ''

    def get_template_sources(self, template_name, template_dirs=None):

        template_split = template_name.split('/')
        if template_split[0] in self.themes:
            self.theme = template_split[0]
        else:
            template_name = ['{}/{}'.format(self.theme,template_name),template_name]

        if not template_dirs:
            template_dirs = self.get_dirs()

        for template_dir in template_dirs:
            if isinstance(template_name,list):
                for i in template_name:
                    try:
                        name = safe_join(template_dir,i)
                    except SuspiciousFileOperation:
                        continue
            else:
                try:
                    name = safe_join(template_dir, template_name)
                except SuspiciousFileOperation:
                    # The joined path was located outside of this template_dir
                    # (it might be inside another one, so this isn't fatal).
                    continue

            yield Origin(
                name=name,
                template_name=template_name,
                loader=self,
            )


    def get_contents(self, origin):
        contents = super(ThemeLoader, self).get_contents(origin)
        return contents

middleware.py

from django.conf import settings

class ThemeMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        # Code to be executed for each request before
        # the view (and later middleware) are called.

        response = self.get_response(request)

        # Code to be executed for each request/response after
        # the view is called.

        return response

    def process_template_response(self,request, response):

        host = request.get_host()

        if host in settings.SITE_CONFIGS:
            theme = settings.SITE_CONFIGS.get(host).get('theme')
            response.template_name = [
                '{}/{}'.format(theme,tn) for tn in response.template_name]
        return response

settings.py

"""
Django settings for themeswap project.

Generated by 'django-admin startproject' using Django 1.11.1.

For more information on this file, see
https://docs.djangoproject.com/en/1.11/topics/settings/

For the full list of settings and their values, see
https://docs.djangoproject.com/en/1.11/ref/settings/
"""

import os

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


# Quick-start development settings - unsuitable for production
# See https://docs.djangoproject.com/en/1.11/howto/deployment/checklist/

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'xgg!g(_w_4rbdd7!ms+15z3w*+re2bb@xvm#2+4$@!%j=s2fg5'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []


# Application definition

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'demo'
]

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'demo.middleware.ThemeMiddleware'
]

SITE_CONFIGS = {
    '127.0.0.1:8000':{
        'theme':'blue'
    },
    '127.0.0.1:8001': {
        'theme':'green'
    },
}

ROOT_URLCONF = 'themeswap.urls'

TEMPLATES = [
    {
        'BACKEND': 'django.template.backends.django.DjangoTemplates',
        'DIRS': [
            '/home/brian/.virtualenvs/tmp-5d1d95d6be51b0b5/themeswap/demo/templates'
        ],
        'APP_DIRS': False,
        'OPTIONS': {
            'context_processors': [
                'django.template.context_processors.debug',
                'django.template.context_processors.request',
                'django.contrib.auth.context_processors.auth',
                'django.contrib.messages.context_processors.messages',
            ],
            'loaders':[
                'demo.loader.ThemeLoader'
            ]
        },
    },
]

WSGI_APPLICATION = 'themeswap.wsgi.application'


# Database
# https://docs.djangoproject.com/en/1.11/ref/settings/#databases

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}


# Password validation
# https://docs.djangoproject.com/en/1.11/ref/settings/#auth-password-validators

AUTH_PASSWORD_VALIDATORS = [
    {
        'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
    },
    {
        'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
    },
]


# Internationalization
# https://docs.djangoproject.com/en/1.11/topics/i18n/

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'UTC'

USE_I18N = True

USE_L10N = True

USE_TZ = True


# Static files (CSS, JavaScript, Images)
# https://docs.djangoproject.com/en/1.11/howto/static-files/

STATIC_URL = '/static/'