nginx not returning Cache-Control header from upstream gunicorn

I'm using WhiteNoise to serve static files from a Django app running under gunicorn. For some reason, the Cache-Control and Access-Control-Allow-Origin headers returned by the gunicorn backend are not being passed back to the client through the nginx proxy.

Cache-Control

Access-Control-Allow-Origin

Here's what the response looks like for a sample request to the gunicorn backend:

% curl -I -H "host: www.myhost.com" -H "X-Forwarded-Proto: https" http://localhost:8000/static/img/sample-image.1bca02e3206a.jpg

HTTP/1.1 200 OK
Server: gunicorn/19.8.1
Date: Mon, 02 Jul 2018 14:20:42 GMT
Connection: close
Content-Length: 76640
Last-Modified: Mon, 18 Jun 2018 09:04:15 GMT
Access-Control-Allow-Origin: *
Cache-Control: max-age=315360000, public, immutable
Content-Type: image/jpeg


When I make a request for the same file via the nginx server, the two headers are missing.

% curl -I -H "Host: www.myhost.com" -k https://my.server.com/static/img/sample-image.1bca02e3206a.jpg

HTTP/1.1 200 OK
Server: nginx/1.10.3 (Ubuntu)
Date: Mon, 02 Jul 2018 14:09:25 GMT
Content-Type: image/jpeg
Content-Length: 76640
Last-Modified: Mon, 18 Jun 2018 09:04:15 GMT
Connection: keep-alive
ETag: "5b27758f-12b60"
Accept-Ranges: bytes


My nginx config is pretty much what is documented in the gunicorn deployment docs, i.e. I haven't enabled nginx caching (nginx -T | grep -i cache is empty) or done anything else I would think is out of the ordinary.

nginx -T | grep -i cache

What am I missing?

location /

2 Answers
2

The problem is that you have

location / {
try_files $uri @proxy_to_app;
}


directive in nginx config, so nginx just serves files himself and gunicorn doesn't even knows about it, and of course can't add headers.

It turns out I had forgotten the root directive I had configured many months ago, which was now picking up the static files. My error was in assuming that since I hadn't configured a location /static directive, nginx would be proxying all requests to the backend.

root

location /static

The solution for me was to remove the $uri reference from the try_files directive:

$uri

try_files

location / {
try_files /dev/null @proxy_to_app;
}


Alternatively, I could have simply put the contents of the @proxy_to_app location block directly inside the location / block.

@proxy_to_app

location /

Thanks to Alexandr Tatarinov for the suggestion in the comments.

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