python - Serve protected media files with django

Question

I'd like Django to serve some media files (e.g. user-uploaded files) only for logged-in users. Since my site is quite low-traffic, I think I will keep things simple and do not use django-sendfile to tell Nginx when to serve a file. Instead I'll let Django/Gunicorn do the job. To me this seems a lot simpler and for a low traffic site this maybe more secure.

But what is the best way to organize the file storage location? Media files are all stored below MEDIA_ROOT and this directory is served by Nginx in production. If I upload my files to MEDIA_ROOT/protected/ I have to tell Nginx not to serve the files in the subdirectory protected.

But is this a good idea? It seems a litte risky to me to allow Nginx access /media/ in the first place and then protect the subdirectory /media/protected/. Wouldn't it be better not to use a subdirectory of MEDIA_ROOT to store protected files?

But if I try something like this quick-and-dirty in my model:

upload_to='../protected/documents/%Y/%m/'

Django complains:

SuspiciousFileOperation at /admin/core/document/add/
The joined path (/home/me/projects/project/protected/documents/2016/09/test.file) is located outside of the base path component (/home/me/projects/project/media)

So I thing it is not good practice to "leave" the MEDIA_ROOT.

What is the best solution to store and serve protected media files?

Answer 1

I now came up with the following solution:

I have this in my Django settings:

MEDIA_ROOT = "/projects/project/media/"
MEDIA_URL = "/media/

In my models I do either:

document = models.FileField(upload_to="public/documents")

or

document = models.FileField(upload_to="protected/documents")

This way, I now have the two subdirectories 'public' and 'protected' in my media files directory.

Nginx or Djangos development server only serves the files in the 'public' subdirectory.

For Djangos development server:

if os.environ["ENVIRONMENT_TYPE"] == 'development':
    urlpatterns += static(settings.MEDIA_URL + "public/", document_root=settings.MEDIA_ROOT + "public/")

And for Nginx (used in production):

location /media/public/ {
    alias   /projects/project/media/public/;
}

When I want to serve a protected document, I do the following:

In urls.py:

url(r'^media/protected/documents/(?P<file>.*)$', core.views.serve_protected_document, name='serve_protected_document'),

And in views.py:

@login_required()
def serve_protected_document(request, file):
    document = get_object_or_404(ProtectedDocument, file="protected/documents/" + file)

    # Split the elements of the path
    path, file_name = os.path.split(file)

    response = FileResponse(document.file,)
    response["Content-Disposition"] = "attachment; filename=" + file_name

    return response

I would appreciate any comments! Are there better ways to implement this?