sample codes of ansible role argument validation

ansible.cfg

[defaults]
stdout_callback = debug
stderr_callback = debug

hosts.ini

[default]
localhost ansible_connection=local ansible_python_interpreter=${HOME}/.pyenv/shims/python3

roles-sample-meta-argument_specs.yml

argument_specs:
  main:
    short_description: Sample role argument validation.
    options:
      required_vars:
        type: "bool"
        required: true
        description: "This variable is required"

roles-sample-tasks-main.yml

- name: Echo localhost's hostname
  ansible.builtin.shell: echo {{ inventory_hostname }}
  register: result

- name: The result is supposed to be "localhost"
  debug:
    var: result.stdout

validation.yml

- hosts: localhost
  gather_facts: no
  roles:
    - role: sample