Vars plugins inject additional variable data into Ansible runs that did not come from an inventory source, playbook, or command line. Playbook constructs like 'host_vars' and 'group_vars' work using vars plugins.
You can activate a custom vars plugins by either dropping it into a ``vars_plugins`` directory adjacent to your play, inside a role, or by putting it in one of the directory sources configured in :ref:`ansible.cfg <ansible_configuration_settings>`.