Ansible facts
From wikinotes
Ansible has some useful built-in variables.
Most of them seem to be built in to /usr/local/lib/python2.7/site-packages/ansible/module_utils/facts.py
List all variables on a particular machine
ansible -m setup <hostname>
Some useful Variables
ansible_os_family == "RedHat"
ansible_distribution == "Debian"
ansible_distribution_major_version == "7"