These kind of projects are a lot of fun. I wrote a simple one, in Ruby, using Sinatra here:

https://github.com/skx/web-file-publisher

But then as an experiment I wrote another which uses TOTP to authenticate uploads, so you can upload a file directly via CURL with a suitable TOTP device. This is written in golang:

https://github.com/skx/go-experiments/tree/master/publishr

Using TOTP limits compromise if your upload is sniffed, although I run it behind SSL so I'm protected against that regardless.

Interesting project though; and I like that you can deploy it via Docker.