The docker container encapsulates a nginx reverse proxy as well as a python backend that serves files associated with documents in a CouchDB database (also run in a docker container, see here.
This docker is based off of nginx/latest and includes a reverse proxy in front of the nEDM CouchDB server.
Most requests are simply forwarded to the CouchDB backend and the nginx server listens on both the 80 and 5984 ports (serving up the same content on both).