River4 is a Nodejs application, and the container provides what is needed to run River4 in Docker. The server uses an OPML file that includes an RSS subscription list that Frank McPherson maintains. The Github repository for River4 is at https://github.com/scripting/river4. The Github repository where you can find the source Dockerfile and sample RSS subsription files is at https://github.com/fmcpherson/DockerizedRiver4.
To use: docker run -d -p 1337:1337 fmcpherson/river4
To open in a web browser, enter [host computer IP address]:1337 in the address bar