Ansible - Child Group (Children|Group of Group)

About

A group of a group is called a child group.

The relation is defined through the use of the children key word.

Articles Related

Properties

Any host that is member of a child group is automatically a member of the parent group.
A child group’s variables will have higher precedence (override) a parent group’s variables.
Groups can have multiple parents and children, but not circular relationships.
Hosts can also be in multiple groups, but there will only be one instance of a host, merging the data from the multiple groups.

Management

Definition

Create a group of a group relation using :

the :children suffix in INI
or the children: entry in YAML

Example: The group parent1 has two children group1 and group2

ini

[childgroup2]
host1
host2

[childgroup1]
host2
host3

[parent1:children]
childgroup1
childgroup2

yaml

all:
    children:
        parent1:
            children:
                childgroup1:
                    host1:
                    host2:
                childgroup2:
                    host3:
                    host4:

Documentation / Reference

https://docs.ansible.com/ansible/latest/user_guide/intro_inventory.html#groups-of-groups-and-group-variables