Document integration of ObjectDownloadView with NGINX acceleration

[johnthagen]

Currently, there is not an example/documentation for how to integrate ObjectDownloadView with NGINX XAccelRedirectMiddleware. This would be a helpful example for new users.

[johnthagen]

@Natim I'm currently looking into this and will submit a PR if/when I figure it out. Do you have any recommendations for this issue?

[johnthagen]

Specifically, the type of View I am trying to accelerate is:

https://github.com/jazzband/django-downloadview/blob/563b2a4f7b354cb930aa7067e6e1341dbb34f5e7/demo/demoproject/object/views.py#L5-L6

https://github.com/jazzband/django-downloadview/blob/563b2a4f7b354cb930aa7067e6e1341dbb34f5e7/demo/demoproject/object/urls.py#L6-L11

[johnthagen]

As a note, ObjectDownloadView is listed as supported for acceleration in the docs: https://django-downloadview.readthedocs.io/en/latest/optimizations/index.html#supported-features-grid

[ghost]

@johnthagen Did you manage to get it working?

[johnthagen]

@amarandon I did not. The challenge I had was that by using object primary keys, I couldn't find a corollary to how to translate those into something to pass NGINX.

I think this would be a very important addition to this library, but after trying for some time I could not figure it out. I do hope that someone is able to and can share their findings with the community.

[johnthagen]

@Natim Do you have any insights or directions someone could take who is trying to discover how to do this? Is this something that is intended to be supported?

[Natim]

I guess what you are looking for is probably https://www.nginx.com/resources/wiki/start/topics/examples/x-accel/

• https://github.com/jazzband/django-downloadview/blob/45e1219275f9549b60fd8265737171ac450f2161/demo/demoproject/object/views.py
• https://github.com/jazzband/django-downloadview/blob/45e1219275f9549b60fd8265737171ac450f2161/demo/demoproject/nginx/views.py

Basically your ObjectView will return an URL that will be transmitted in a X-Accel header to Nginx which will handle the file.

[ghost]

@Natim So if I understand correctly ObjectDownloadView should add the correct header out of the box and we only need to configure nginx to make use of it? I just had a look in browser's devtools and that doesn't seem to be the case :thinking:

[Natim]

If I understand the code correctly it would work like that if you configure the XAccelMiddleware to monitor the path that your ObjectResponse will use.

[ghost]

@Natim What confuses me is what to put in DOWNLOADVIEW_RULES and how it relates to Django URLs configuration and Nginx configuration.

I have a Photo model like this:

class Photo(models.Model):
    file = models.ImageField(upload_to='uploads/%Y/%m/%d/')

And an ObjectDownloadView configured in urls.py like this:

path('photos/<int:pk>', ObjectDownloadView.as_view(model=Photo), name='photo_file'),

This works as expected: files are served through the Python view.

Now in settings.py I've added django_downloadview.SmartDownloadMiddleware at the end of my MIDDLEWARE lists. I've enabled the nginx backend with DOWNLOADVIEW_BACKEND = "django_downloadview.nginx.XAccelRedirectMiddleware" but now I'm confused as to how I should configure DOWNLOADVIEW_RULES. I tried this:

DOWNLOADVIEW_RULES = [
    {
        'source_url': '/photos/',
        'destination_url': '/uploads/',
    },
]

Along with this entry in nginx config:

location /uploads/ {
      internal;
      # /home/myuser/myproject contains a directory named 'uploads' which contains uploaded photos
      alias /home/myuser/myproject;
}

But this doesn't seem to change anything. In fact I'm not even sure of how to verify that it works. I was kind of expecting a line in nginx log files saying it did the internal redirection but I'm not sure if this expectation is reasonable.

[Natim]

I think the issue is with

DOWNLOADVIEW_RULES = [
    {
        'source_url': '/photos/',
        'destination_url': '/uploads/',
    },
]

can you try:

DOWNLOADVIEW_RULES = ['/uploads']

[benoitbryon]

Disclaimer: I had a very quick look at this thread and I've not been coding with Django for some time now...

I haven't figured out where is the issue at the moment.

I'm not even sure of how to verify that it works

As far as I remember, in order to debug, you can:

• disable X-Accel backend in Django settings and check that files are served. You did that already if I understood well.
• enable X-Accel backend in Django settings but comment /uploads/ section in Nginx configuration, then check HTTP response.
  • If response does have X-Accel-Redirect header, then it looks like Nginx didn't catch this header (or the value of the header), so check Nginx configuration.
  • If response doesn't have X-Accel-Redirect header, then it looks like the middleware didn't catch the URL as expected. So check Django configuration.

There is also some assert_x_accel_redirect() utility to create tests. It may be useful to check that middleware catches the response and transforms it to X-Accel as expected. See https://django-downloadview.readthedocs.io/en/latest/optimizations/nginx.html#test-responses-with-assert-x-accel-redirect