hosts/tasks/main.yaml

---
- block:
  - name: add ip address of all hosts to all hosts
    lineinfile:
      dest: /etc/hosts
      regexp: '.*{{ item }} {{ item.split(".")[0] }}$'
      line: "{{ hostvars[item].ansible_host }} {{ item }} {{ item.split('.')[0] }}"
      state: present
    when:
      - hostvars[item].ansible_host is defined
      - pin_hosts
    with_items: "{{ groups.all }}"
    tags:
      - hosts

  become: true