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Extend boolean values section in playbooks_variables #1285

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06b1850
Extend boolean values section in playbooks_variables
skilyazhnev Apr 18, 2024
6c41ec7
Remove 0.0\1.0 values
skilyazhnev Apr 20, 2024
9578876
Add
skilyazhnev Apr 20, 2024
1262ca5
Grammar fix
skilyazhnev May 21, 2024
4e4d688
Grammar\Style fix
skilyazhnev May 21, 2024
04f8f13
Split Native boolean
skilyazhnev Jun 1, 2024
7fc8f42
Example of Interpretable as Boolean
skilyazhnev Jun 1, 2024
cc8b337
Update docs/docsite/rst/playbook_guide/playbooks_variables.rst
skilyazhnev Jun 4, 2024
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Update docs/docsite/rst/playbook_guide/playbooks_variables.rst
skilyazhnev Jun 4, 2024
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Update docs/docsite/rst/playbook_guide/playbooks_variables.rst
skilyazhnev Jun 4, 2024
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71 changes: 64 additions & 7 deletions docs/docsite/rst/playbook_guide/playbooks_variables.rst
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Expand Up @@ -101,19 +101,76 @@ Boolean variables
=================

Ansible accepts a broad range of values for boolean variables: ``true/false``, ``1/0``, ``yes/no``, ``True/False`` and so on. The matching of valid strings is case insensitive.
While documentation examples focus on ``true/false`` to be compatible with ``ansible-lint`` default settings, you can use any of the following:
Documentation examples focus on ``true/false`` to be compatible with ``ansible-lint`` default settings. However, you can use any of the following values:

Native boolean
--------------

Ansible treats these values as native booleans:

.. table::
:class: documentation-table

=============================================================================================== ====================================================================
Valid values Description
=============================================================================================== ====================================================================
``True`` , ``'true'`` , ``'t'`` , ``'yes'`` , ``'y'`` , ``'on'`` , ``'1'`` , ``1`` , ``1.0`` Truthy values
================= =================
Valid values Description
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This is not really 'ansible native' but YAML that uses true and false and the rest of the list below, it would be 'more true' that True and False are the 'native' options as Ansible evaluation happens inside Python and those are the 'Python native booleans', this also depends on context as inside a {{ }} expression it is Jinja doing the evaluation, which is again using Python under the hood.

================= =================
``true`` Truthy values

``false`` Falsy values

================= =================

Implicit boolean
----------------

Ansible recognizes these values as booleans:

.. table::
:class: documentation-table

================================================================================= ====================================================================
Valid values Description
================================================================================= ====================================================================
``yes`` , ``Yes`` , ``YES`` , ``True`` , ``TRUE`` , ``on`` , ``On`` , ``ON`` Truthy values

``no`` , ``No`` , ``NO`` , ``False`` , ``FALSE`` , ``off`` , ``Off`` , ``OFF`` Falsy values

================================================================================= ====================================================================

Interpretable as boolean
------------------------

``False`` , ``'false'`` , ``'f'`` , ``'no'`` , ``'n'`` , ``'off'`` , ``'0'`` , ``0`` , ``0.0`` Falsy values
You need to use the ``| bool`` filter to interpret these strings values as native booleans in logical expressions. Boolean expressions also work with these values without a filter, but Ansible interprets them in Python style.

=============================================================================================== ====================================================================
.. table::
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@bcoca bcoca Jun 4, 2024 •
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the bool filter, while is it Jinja, it is an Ansible customization which approximates (but does not really match) the YAML booleans, the table below is incorrect as this is the actual code:

    if a is None or isinstance(a, bool):
        return a
    if isinstance(a, string_types):
        a = a.lower()
    if a in ('yes', 'on', '1', 'true', 1):
        return True
    return False

so it realy only converts 'matching True' and everything else is False

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though this is something I'm planning to fix so they are closer to YAML by default but can be 'pythonic' otherwise.

:class: documentation-table

================================================================================= ====================================================================
Valid values Description
================================================================================= ====================================================================
``'true'`` , ``'t'`` , ``'yes'`` , ``'y'`` , ``'on'`` , ``'1'`` , ``1`` Truthy values

``'false'`` , ``'f'`` , ``'no'`` , ``'n'`` , ``'off'`` , ``'0'`` , ``0`` Falsy values

================================================================================= ====================================================================

For example, using ``'false'`` as a condition to run tasks:

.. code-block:: yaml

- hosts: web_servers
vars:
condition_var: 'false'
tasks:
- name: This task will run
debug:
msg: "{{ condition_var }}"
when: condition_var

- name: This task will be skipped
debug:
msg: "{{ condition_var }}"
when: condition_var | bool

.. _list_variables:

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