Stop! Don’t compile that ruby installation!

Next time you are setting out to provision a box with Ruby on it, instead of downloading the source and libraries and compiling it, and waiting for 15 minutes, use the pre-built binaries at the Brightbox:

Ubuntu: https://www.brightbox.com/docs/ruby/ubuntu/

In a nutshell:

apt-get install build-essential software-properties-common
apt-add-repository ppa:brightbox.com/ruby-ng
apt-get update && apt-get install ruby2.4 ruby2.4-dev
apt-get install ruby-switch