ruby required for compiling webpack assets in rails build, missing from nodejs buildpack and stack 22

[neontuna]

I'm not sure whether to open this here or under the nodejs buildpack but the removal of system ruby from Heroku Stack 22 is causing issues.

I'm in the middle of upgrading our Rails app from 6 to 7, and from Ruby 2.7 to 3.3. Part of this has meant a switch to jsbundling-rails, propshaft, and webpack 5. We use the rails-erb-loader, specifically for generating rails route helpers in JS.

rails-erb-loader requires ruby (or rails runner) to run. I have the nodejs buildpack listed before ruby in the Heroku config (so I can specify node version) and because of this when Yarn runs the compile step, ruby is missing. This causes the compile to fail

remote: /usr/bin/env: ‘ruby’: No such file or directory

For now I'll be downgrading to stack 20 but I don't see a way to fix this. It would be nice if we could just reinstall system ruby on stack 22.

/edit

actually, that's not going to work either - because system ruby on stack 20 is 2.7. So yeah... this is a real pickle for us :/