Learn how to develop Ruby scripts without having to worry about installing language rumtime(s) or tools and their dependencies!
Docker is the latest craze in the computing world. Ok, maybe not. But it's a great tool for building environments custom-tuned for your code to run in; you can wrap up any dependencies into container images that can be transported from one machine to another.
This is great, because you can guarantee that the FRIGGEN VERSION OF NOKOGIRI THAT YOU COMPILED AND INSTALLED in your docker container on your local machine is the same one that is running in Dev, Stage and Prod. This same set of concerns can be solved for sharing local development environments too! Without having to deal with Ansible and other machine-provisioning tools. If the machine can run docker, it can run your app/code.
Any issues - write them down and walk out of your room. Throw out the issue in the nearest bin. This is a toy course (sorry).