How Exactly Does Ansible Parse Boolean Variables?

Question

In Ansible, there are several places where variables can be defined: in the inventory, in a playbook, in variable files, etc. Can anyone explain the following observations t

Answer 1

Variables defined in YAML files (playbooks, vars_files, YAML-format inventories)

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YAML principles

Playbooks, vars_files, and inventory files written in YAML are processed by a YAML parser first. It allows several aliases for values which will be stored as Boolean type: yes/no, true/false, on/off, defined in several cases: true/True/TRUE (thus they are not truly case-insensitive).

YAML definition specifies possible values as:

y|Y|yes|Yes|YES|n|N|no|No|NO
|true|True|TRUE|false|False|FALSE
|on|On|ON|off|Off|OFF

Ansible docs confirm that:

You can also specify a boolean value (true/false) in several forms:

create_key: yes
needs_agent: no
knows_oop: True
likes_emacs: TRUE
uses_cvs: false

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Variables defined in INI-format inventory files

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Python principles

When Ansible reads an INI-format inventory, it processes the variables using Python built-in types:

Values passed in using the key=value syntax are interpreted as Python literal structure (strings, numbers, tuples, lists, dicts, booleans, None), alternatively as string. For example var=FALSE would create a string equal to FALSE.

If the value specified matches string True or False (starting with a capital letter) the type is set to Boolean, otherwise it is treated as string (unless it matches another type).

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Variables defined through --extra_vars CLI parameter

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All strings

All variables passed as extra-vars in CLI are of string type.