ansible/roles/hostname/defaults/main.yml

---
hostname__fqdn: "{{ inventory_hostname }}"
hostname__hosts:
  - name:
      - localhost
      - "{{ hostname__fqdn }}"
      - "{{ hostname__fqdn.split('.') | first }}"
    address:
      - 127.0.0.1
      - ::1
  - name:
      - ip6-localhost
      - ip6-loopback
    address:
      - ::1
  - name:
      - ip6-allnodes
    address:
      - ff02::1
  - name:
      - ip6-allrouters
    address:
      - ff02::2
...