Overview
- to know magic variables
- hosts: all
  gather_facts: no
  tasks:
    - name: show Magic | group_names
      debug: var=group_names
    - name: show Magic | groups
      debug: var=groups
    - name: show Magic | inventory_hostname
      debug: var=inventory_hostname
    - name: show Magic | inventory_hostname_short
      debug: var=inventory_hostname_short
    - name: show Magic | play_hosts
      debug: var=play_hosts
    - name: show Magic | inventory_dir
      debug: var=inventory_dir
    - name: show Magic | inventory_file
      debug: var=inventory_file
    # Reserved magic variable
    - name: show Reserved magic | environment
      debug: var=environment