NGINX config proxy_set_header

I don't think that there is a way to explicitly invalidate cached items, but here is an example of how to do the rest. Update: As mentioned by Piotr in another answer, there is a cache purge module that you can use. You can also force a refresh of a cached item using nginx's proxy_cache_bypass - see Cherian's answer for more information.

In this configuration, items that aren't cached will be retrieved from example.net and stored. The cached versions will be served up to future clients until they are no longer valid (60 minutes).

Your Cache-Control and Expires HTTP headers will be honored, so if you want to explicitly set an expiration date, you can do that by setting the correct headers in whatever you are proxying to.

There are lots of parameters that you can tune - see the nginx Proxy module documentation for more information about all of this including details on the meaning of the different settings/parameters: http://nginx.org/r/proxy_cache_path

http {
  proxy_cache_path  /var/www/cache levels=1:2 keys_zone=my-cache:8m max_size=1000m inactive=600m;
  proxy_temp_path /var/www/cache/tmp; 


  server {
    location / {
      proxy_pass http://example.net;
      proxy_cache my-cache;
      proxy_cache_valid  200 302  60m;
      proxy_cache_valid  404      1m;
    }
  }
}

Overly simplified: You need something that executes Python but Python isn't the best at handling all types of requests.

[disclaimer: I'm a Gunicorn developer]

Less simplified: Regardless of what app server you use (Gunicorn, mod_wsgi, mod_uwsgi, cherrypy) any sort of non-trivial deployment will have something upstream that will handle the requests that your Django app should not be handling. Trivial examples of such requests are serving static assets (images/css/js).

This results in two first tiers of the classic "three tier architecture". Ie, the webserver (Nginx in your case) will handle many requests for images and static resources. Requests that need to be dynamically generated will then be passed on to the application server (Gunicorn in your example). (As an aside, the third of the three tiers is the database)

Historically speaking, each of these tiers would be hosted on separate machines (and there would most likely be multiple machines in the first two tiers, ie: 5 web servers dispatch requests to two app servers which in turn query a single database).

In the modern era we now have applications of all shapes and sizes. Not every weekend project or small business site actually needs the horsepower of multiple machines and will run quite happily on a single box. This has spawned new entries into the array of hosting solutions. Some solutions will marry the app server to the web server (Apache httpd + mod_wsgi, Nginx + mod_uwsgi, etc). And its not at all uncommon to host the database on the same machine as one of these web/app server combinations.

Now in the case of Gunicorn, we made a specific decision (copying from Ruby's Unicorn) to keep things separate from Nginx while relying on Nginx's proxying behavior. Specifically, if we can assume that Gunicorn will never read connections directly from the internet, then we don't have to worry about clients that are slow. This means that the processing model for Gunicorn is embarrassingly simple.

The separation also allows Gunicorn to be written in pure Python which minimizes the cost of development while not significantly impacting performance. It also allows users the ability to use other proxies (assuming they buffer correctly).

As to your second question about what actually handles the HTTP request, the simple answer is Gunicorn. The complete answer is both Nginx and Gunicorn handle the request. Basically, Nginx will receive the request and if it's a dynamic request (generally based on URL patterns) then it will give that request to Gunicorn, which will process it, and then return a response to Nginx which then forwards the response back to the original client.

So in closing, yes. You need both Nginx and Gunicorn (or something similar) for a proper Django deployment. If you're specifically looking to host Django with Nginx, then I would investigate Gunicorn, mod_uwsgi, and maybe CherryPy as candidates for the Django side of things.