ansible-base/inventory_template/inventory.yml

all:
  vars:
    ansible_user: ansible
    ansible_become: yes
    ansible_python_interpreter: auto_silent
  children:
    function:
      children:
        backup_server:
          hosts:
            myFirstDebianHost.example.org:
        authority_dns_server:
          hosts:
            mySecondCentOSHost.anotherexample.org:
        resolver_dns_server:
          hosts:
            myFirstCentOSHost.example.org:
        web_server:
          hosts:
            myFirstGentooHost.wirebrass.fr:
        munin_server:
          hosts:
            myFirstGentooHost.example.org:
        ldap_server:
          hosts:
            mySecondGentooHost.anotherexample.org:
    os:
      children:
        os_gentoo:
          hosts:
            myFirstGentooHost.example.org:
            mySecondGentooHost.anotherexample.org:
        os_debian:
          hosts:
            myFirstDebianHost.example.org:
            mySecondDebianHost.anotherexample.org:
        os_centos:
          hosts:
            myFirstCentOSHost.example.org:
            mySecondCentOSHost.anotherexample.org:
        os_openbsd:
          hosts:
            myFirstOpenBSDHost.example.org: