---
- name: Gather package facts
  package_facts:
    manager: apt

- name: Check if ifupdown2 is installed
  set_fact:
    must_mask: "{{ 'ifupdown2' not in ansible_facts.packages }}"

- name: Mask networking before installing ifupdown2
  systemd:
    name: networking.service
    masked: true
  when: must_mask

- name: Install ifupdown2
  apt:
    name: ifupdown2

- name: Unmask networking now that ifupdown2 is installed
  systemd:
    name: networking.service
    masked: false
  when: must_mask

- name: Configure ifupdown2
  template:
    src: interfaces.j2
    dest: /etc/network/interfaces
    owner: root
    group: root
    mode: u=rw,g=r,o=
  notify:
    - Restart networking

- name: Enable and start networking
  systemd:
    name: networking.service
    state: started
    enabled: true
...