So as the inventory gets larger, you'll want to group accordingly.
So let us look how hosts could be arranged into groups in your inventory.
A design pattern that's worked well for me in production networks is
arranging your systems into groups based on functionality.
However,
the Ansible documentation provides good guidance when deciding how
to group hosts, and here, you need to answer the following
questions. Firstly, the what, an application,
a stack, or microservice, for example, a database server or a web server.
Then you need to ask yourself, where? This could be a data center or region.
Finally, you want to ask yourself, when? This could be the
development stage or production or staging.
So you can define your own groups in the inventory file, and by default,
Ansible uses a .INI file format for inventory files.
So in this INI format, configuration values are grouped into sections.
Keep in mind that systems and inventory can exist in more than one group,
and groups can even consist of other groups. Also, keep in mind it's
possible this hosts without a group.
So a good recommendation would be to have one inventory file
that fills in these groups with hosts, for example,
preproduction or staging environments, and then you could have another
inventory file for the production versions of these groupings.
A big advantage of this is that the content of the playbook does not need to
change when executing on either of these environments because it refers to the
generic group names that exist in both inventories.
In this case, you can simply refer to the correct inventory
to execute in your desired environment.
Ansible also allows you to find groups that are made up of other groups,
and Ansible supports this well with numeric patterns. Ansible also
supports alphabetic characters to specify ranges. So keep in mind that
those parameters are variables and have a special meaning to Ansible,
unlike arbitrary variables.