Unable to install sass gem on CentOS 6.9 with Ruby 2.4

Something changed recently, preventing a VM from fully provisioning. Tracking it down was a bit of a PiTA.

OS: CentOS 6.9
Ruby: 2.4 – installed from source with the gearlingguy.ruby ansible role
Gems to be installed: sass

The issue is with the ffi ruby gem.

Looking at the releases in github, a recent release updated the required version of autoconf installed on the system. Fine for modern systems, not so much for CentOS 6.9.

The solution is to install the ffi ruby gem with the version prior to this recent change:

This then allows sass to be installed without complaint!