Installing Installing inventory plugins isn’t intuitive, and the documentation available on this process isn’t immediately clear. The instructions found on this page Ansible Documentation can be adapted for the Rackspace plugin.
It boils down to this for the Rackspace plugin:
Grab the latest version of rax.py from the plugins/inventory folder on GitHub. Raw GitHub Link Place this file on your Ansible master. The location doesn’t matter that much, but convention says to put it in /etc/ansible/rax.