Description of problem:

In our downstream docs we instruct users to use /etc/ansible/hosts as their inventory file, but to configure ceph by defining the appropriate variables in /usr/share/ceph-ansible/group_vars. Correct ansible usage is to always put your group_vars directory and configuration in the same directory as your inventory. If you don't do this ansible can not find the configuration found in your group_vars.

Link to downstream docs: https://access.redhat.com/documentation/en/red-hat-ceph-storage/2/single/installation-guide-for-red-hat-enterprise-linux#installing_red_hat_ceph_storage_using_ansible

Here's a reference to the upstream ansible docs pertaining to this: http://docs.ansible.com/ansible/intro_inventory.html#splitting-out-host-and-group-specific-data