Using rumor with Docker container on MacOS

[Carl Sorensen]

I have a friend who has seen my lilypond work and would like to get involved 
with lilypond.

He would like to use a MIDI keyboard, rather than the keyboard, to be able to 
input music.

Frescobaldi with rumor appears to meet his needs, except for the fact that 
rumor is only supported on Linux systems, and he uses MacOS

I have seen no MacPorts or Homebrew solutions for using rumor.  So I was hoping 
to set up rumor to use with one of the Docker containers for LilyDev 
(preferably the lilypond container, rather than the lilydev container).

I have never used Docker before, but I was able to get it set up with a few 
false starts (thanks, Federico!).

Could somebody (maybe Federico) give me some pointers on how I might add rumor 
to a Docker container?  Or maybe set up a new Docker container?  Since rumor 
doesn't add the music into Lilypond files, as I understand it, but instead 
creates music to be pasted into a lilypond source file, I think I could use 
rumor in a Docker container, and paste the results of a rumor run into a 
Frescobaldi window.

Anyway, if anybody could give me a brief synopsis of how I would go about it 
(or even better, if somebody knows of a Docker setup, Homebrew cask, or 
MacPorts portfile that supports rumor), could you please let me know?

Thanks,

Carl