community.general/examples/playbooks/group_by.yml

---
# Example playbook to demonstrate the group_by action plugin.
#
# as we know, the setup module will automatically run in each play, and sets up various
# facts.  We can then create temporary (in memory only) groups based on those facts, which
# are useful ways of selecting similar sets of hosts.
#
# Additionally, we can use the 'register' keyword in Ansible to set similar variables
# and use those for grouping.  This is not shown in this example.

- hosts: all

  tasks:

  - name: Create a group of all hosts by operating system
    action: group_by key=${ansible_distribution}-${ansible_distribution_version}

# the following host group does not exist in inventory and was created by the group_by
# module.

- hosts: CentOS-6.2

  tasks:

  - name: ping all CentOS 6.2 hosts
    action: ping

- hosts: CentOS-6.3

  tasks:
  
  - name: ping all CentOS 6.3 hosts
    action: ping