After trying out a new image on Amazon, I was unable to install basic “extra” packages like ack (and if you are using grep, please replace it with ack).  This was an AMI (disk image) so something was missing between ansible the original author’s steps run before making the AMI.  Messing with all the files in /etc/yum.repos.d/ and doing every yum command under the sun yeilded nothing useful.  After a few hours wasted, it turns out the magic command all along was:

sudo yum install epel-release

For ansible (be sure this is before the other yum package installs that require it)

- name: add extras repo for cents
  become: true
  yum: >
    pkg="epel-release"