CGI is great. Sadly nginx doesn't support it natively as opposed to lighttpd.

I like this project for adding CGI to nginx: https://github.com/pjincz/nginx-cgi

There's also methods of starting Rack applications directly form nginx via passenger[1]. Rack is the CGI like interface for ruby webapps: https://github.com/rack/rack It easily allows for writing applications and middleware with a few lines of ruby.

[1]: https://www.phusionpassenger.com/documentation/Users%20guide...