WHITENOISE_STATIC_PREFIX still required if django app deployed on subpath

The docs for WHITENOISE_STATIC_PREFIX currently say

Default: Path component of settings.STATIC_URL (with settings.FORCE_SCRIPT_NAME removed if set) … If your application is not running at the root of the domain and FORCE_SCRIPT_NAME is set then this value will be removed from the STATIC_URL path first to give the correct prefix.

I understand this to mean if in my settings.py I have

FORCE_SCRIPT_NAME = "/dev"
STATIC_URL = "{}/static/".format(FORCE_SCRIPT_NAME)

WHITENOISE_STATIC_PREFIX will automatically be /static/

However, this is not the case and i still need to explicitly set in my settings.py

WHITENOISE_STATIC_PREFIX = "/static/"

otherwise static files will not work.

Is this a bug, or am I misunderstanding something in the docs? I did see https://github.com/evansd/whitenoise/issues/164 which seems similar but different enough (no mention of FORCE_SCRIPT_NAME) where it explicitly mentions needing to do this, but that issue is from 2017 and seems to contradict the above documentation.

am using

• whitenoise 5.2.0
• zappa 0.52.0
• django 3.1.4

[stewartadam]

I believe this is still an issue, I’ve been experiencing incorrect pathing from static assets with whitenoise which I spent a bit of time debugging in https://github.com/TandoorRecipes/recipes/issues/1878 and https://code.djangoproject.com/ticket/34028.

The root cause seems to be that recent Django versions cache the prefix and setting values based on their first access. Normally first access is a HTTP request so SCRIPT_NAME would be set on it and all is well… However, whitenoise attempts to access the configured STATIC_URL during middleware initialization, as you can see here:

recipes-web_recipes-1  |   File "/opt/recipes/recipes/wsgi.py", line 15, in <module>
recipes-web_recipes-1  |     _application = get_wsgi_application()
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/django/core/wsgi.py", line 13, in get_wsgi_application
recipes-web_recipes-1  |     return WSGIHandler()
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/django/core/handlers/wsgi.py", line 126, in __init__
recipes-web_recipes-1  |     self.load_middleware()
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/django/core/handlers/base.py", line 61, in load_middleware
recipes-web_recipes-1  |     mw_instance = middleware(adapted_handler)
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/whitenoise/middleware.py", line 47, in __init__
recipes-web_recipes-1  |     self.configure_from_settings(settings)
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/whitenoise/middleware.py", line 86, in configure_from_settings
recipes-web_recipes-1  |     self.static_prefix = urlparse(settings.STATIC_URL or "").path
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/django/conf/__init__.py", line 93, in __getattr__
recipes-web_recipes-1  |     val = self._add_script_prefix(val)
recipes-web_recipes-1  |   File "/opt/recipes/venv/lib/python3.10/site-packages/django/conf/__init__.py", line 144, in _add_script_prefix
recipes-web_recipes-1  |     traceback.print_stack()

Since this is during initialization and outside a HTTP request context, SCRIPT_NAME is absent and therefore the Django prefix gets incorrectly returned as ‘/’ (i.e. STATIC_URL gets set to ‘/static/’ and then remains that way). This causes all the asset URIs to be wrong when a real request comes in with SCRIPT_NAME header set.

In theory setting FORCE_SCRIPT_NAME should address this by short-circuiting SCRIPT_NAME and ensuring the Django prefix is set correct on whitenoise middleware initialization, but in my testing I didn’t see that behavior. The prefix only gets set on the first HTTP request, so until then even with FORCE_SCRIPT_NAME set the prefix is still ‘/’ according to Django - and that’s what whitenoise sees. Note sure if thats a Django issue or if whitenoise needs to add an explicit check for FORCE_SCRIPT_NAME.

[bluespider42]

I had a similar issue which I solved by setting WHITENOISE_STATIC_PREFIX = "/static/" although I’m not sure why this worked.