This is my first set up of a webserver, so it's an experimental learning experience. I had successfully got lighttpd using mod_fastcgi (https://redmine.lighttpd.net/projects/1/wiki/docs_modfastcgi) working to send a request to a separate process via a TCP socket. It sends the request using the FastCGI protocol.
But is there a module or way to send raw data to the TCP socket without the FastCGI protocol? Alternatively, if not lighttpd, is there another lightweight webserver that does allow sending basic requests to a TCP socket without any extra protocol wrapping around it?
I think you are looking for lighttpd mod_proxy.
https://redmine.lighttpd.net/projects/lighttpd/wiki/Docs_ModProxy