---
- name: Set etc_hosts_file if running in Docker
  set_fact:
    etc_hosts_file: "{{ __etc_hosts_file_docker }}"
  when:
    - ansible_virtualization_type == "docker"


- name: Deploy {{ __etc_hosts_file }}
  template:
    src: templates/etc_hosts.j2
    dest: "{{ __etc_hosts_file }}"
    mode: 0644


...