Serving a Request from Gunicorn

Serving a request from gunicorn

looking at the quickstart guide, you probably should have run

(tutorial) $ ../bin/gunicorn -w 4 myapp:app

which should have produced a line that looks a bit like:

Listening at: http://127.0.0.1:8000

Among others. see if you can access your site at that address.

Also Note that 127.0.0.1 is the loopback address; accessible only from that host itself. To get gunicorn to bind to a different option, pass it --bind 0.0.0.0:80, as Jan-Philip suggests.

Since you mention rackspace, its possible that you may need to adjust the firewall settings to allow incoming connections to the desired ports.

I can't serve gunicorn requests from nginx

Here's a sample NGINX config which I know to work as a reverse proxy with Gunicorn.

#Config Contents
server {
    listen       80;
    server_name  site.your.domain;
    # Or use the following if you do not have a domain
    #server_name 123.123.123.123;

    location / {
        proxy_pass http://127.0.0.1:5000;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Scheme $scheme;
    }
}

The Gunicorn Run string looks like

gunicorn --bind localhost:5000 flask_app:app

As a sanity check, you can check which processes are listening to which ports using

lsof -i -P -n | grep LISTEN

Make sure your server allows traffic on port 80 from at least your IP address.

Django-App with Nginx and Gunicorn - Requests get lost?

Thanks to the ideas from @SDRJ, I could solve this issue on my own.

Original server specs

• VM with 2 CPUs
• Nginx as reverse proxy
• Gunicorn running with 3 workers and 1 thread per worker

Load test

Although a small amount of requests had a average runtime of 0.05 seconds, a load test reveiled that the server isn't able to process more than 200 requests at a time.
This resulted in Nginx signaling "Bad Request 502" for the further requests, an indication that Nginx can't reach Gunicorn anymore.

Optimised specs

Changing the configuration of gunicorn to:

• 3 workers with 4 threads

This resulted in much better performance. The server was able to easily handle more than 4000 requests at a time.

Conclusion

Is it possible, that requests get lost when Nginx/Gunicorn is not able to handle the amount of requests?

Yes, it is. "Lost" might be an unfavorable description, but it can happen that some requests do not get processed.

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