---
- name: Create inventory based on extra_vars
  hosts: localhost
  connection: local
  gather_facts: no
  become: no


  vars_files:
    - vars/defaults.yml


  vars:
    __host_inventory: container_inventory
    __host_state    : present

    __hosts:
      - hostname : lab-dev-1
        ip       : 10.10.42.40

      - hostname : lab-dev-2
        ip       : 10.10.42.41

      - hostname : lab-dev-3
        ip       : 10.10.42.42


  tasks:
    - name: Add tower host
      tower_host:
        name:              "{{ tower_hosts_item.hostname | mandatory }}"
        inventory:         "{{ __host_inventory | mandatory }}"
        state:             "{{ __host_state | default('present') }}"
        variables:
          ansible_host:    "{{ tower_hosts_item.ip }}"
        tower_host:        "{{ tower_hostname | default(omit, true) }}"
        tower_username:    "{{ tower_username | default(omit, true) }}"
        tower_password:    "{{ tower_password | default(omit, true) }}"
        tower_oauthtoken:  "{{ tower_oauthtoken | default(omit, true) }}"
        tower_config_file: "{{ tower_config_file | default(omit, true) }}"
        validate_certs:    "{{ tower_validate_certs | default(omit) }}"
      loop: "{{ __hosts }}"
      loop_control:
        loop_var: tower_hosts_item


...