iiab/roles/yarn/tasks/main.yml

# "How do i fail a task in Ansible if the variable contains a boolean value?
# I want to perform input validation for Ansible playbooks"
# https://stackoverflow.com/questions/46664127/how-do-i-fail-a-task-in-ansible-if-the-variable-contains-a-boolean-value-i-want/46667499#46667499

# We assume 0-init/tasks/validate_vars.yml has DEFINITELY been run, so no need
# to re-check whether vars are defined here.  As Ansible vars cannot be unset:
# https://serverfault.com/questions/856729/how-to-destroy-delete-unset-a-variable-value-in-ansible

- name: Assert that "yarn_install is sameas true" (boolean not string etc)
  assert:
    that: yarn_install is sameas true
    fail_msg: "PLEASE SET 'yarn_install: True' e.g. IN: /etc/iiab/local_vars.yml"
    quiet: yes

- name: Assert that "yarn_enabled | type_debug == 'bool'" (boolean not string etc)
  assert:
    that: yarn_enabled | type_debug == 'bool'
    fail_msg: "PLEASE GIVE VARIABLE 'yarn_enabled' A PROPER (UNQUOTED) ANSIBLE BOOLEAN VALUE e.g. IN: /etc/iiab/local_vars.yml"
    quiet: yes

- debug:
    var: yarn_install
- debug:
    var: yarn_enabled
- debug:
    var: yarn_installed


- block:

  - name: Install Yarn if 'yarn_installed' not defined, e.g. in {{ iiab_state_file }}    # /etc/iiab/iiab_state.yml
    include_tasks: install.yml
    when: yarn_installed is undefined

  - name: Add 'yarn' variable values to {{ iiab_ini_file }}
    ini_file:
      path: "{{ iiab_ini_file }}"    # /etc/iiab/iiab.ini
      section: yarn
      option: "{{ item.option }}"
      value: "{{ item.value | string }}"
    with_items:
      - option: name
        value: Yarn
      - option: description
        value: '"Fast, reliable, and secure dependency management.  Comparable to npm.  Released by Facebook in October 2016."'
      - option: yarn_install
        value: "{{ yarn_install }}"
      - option: yarn_enabled
        value: "{{ yarn_enabled }}"

  rescue:

  - name: 'SEE ERROR ABOVE (skip_role_on_error: {{ skip_role_on_error }})'
    fail:
      msg: ""
    when: not skip_role_on_error