How to run ruby code in a jupyter notebook?

I have installed Jupyter with conda, and iruby according to instructions here https://github.com/SciRuby/iruby, and there are 2 ways to start jupyter:

1. iruby notebook (given in the README)
2. In VSCode with the Jupyter extensions

The first method using iruby seems to require ipython and gives the error [TerminalIPythonApp] WARNING | File 'notebook' doesn't exist

The second method seems better, but it is difficult to manage which gems and version are needed.

Is there best practice for using Jupyter with ruby? Is ipython required and supported?