Agreed. As someone currently moving my infrastructure to Dokku, where I have legacy apps on a range of ruby and non-rubies, this approach isn't scalable for my

Agreed. As someone currently moving my infrastructure to Dokku, where I have legacy apps on a range of ruby and non-rubies, this approach isn't scalable for my needs. That said, I wonder if there is a middle ground - where we can use this technique to build a docker container that keeps the copy of ruby, holds known gems, sass caches, etc... all the expensive operations get quietly persisted, but the buildpacks still get run. This container could be created on a per-project basis, so maybe the first push would take longer than the others and that's fine, but instead of it taking 10-15 mins to push a project update, it could take less than 5? One day I might even find the time to try...