inventory-etc-hosts.yaml

---
- hosts: all
  gather_facts: yes
  tasks:
    - name: Update /etc/hosts to resolve other hosts in inventory
      blockinfile:
        path: /etc/hosts
        state: present
        marker: "# {mark} {{ hostvars[item]['inventory_hostname'] }} managed by Ansible task"
        block: |-
          {{ hostvars[item]['ansible_default_ipv4']['address'] }} {{ hostvars[item]['inventory_hostname'] }}
      become: true
      with_items: "{{ play_hosts }}"