create swap on Ubuntu

ansible_create_swap_tasks_main.yml

---
- name: carete swapfile
  command: dd if=/dev/zero of={{ swap_file }} bs={{ ansible_memtotal_mb }} count=1M
  args:
    creates: '{{ swap_file }}'

- file:
    path: '{{ swap_file }}'
    mode: '0600'

- command: file {{ swap_file }}
  register: swap_file_test

- command: mkswap {{ swap_file }}
  when: swap_file_test.stdout.find('swap file') == -1

- name: copy swap config file
  template: src=templates/swapfile.swap.j2 dest=/etc/systemd/system/swapfile.swap

- name: start swapfile.swap
  systemd:
    name: swapfile.swap
    state: restarted
    daemon_reload: yes
    enabled: yes
  become: yes

swapfile.swap.j2

[Unit]
Description=Turn on swap
[Service]
Type=oneshot
Environment="SWAPFILE={{ swap_file }}"
RemainAfterExit=true
ExecStartPre=/usr/sbin/losetup -f ${SWAPFILE}
ExecStart=/usr/bin/sh -c "/sbin/swapon $(/sbin/losetup -j ${SWAPFILE} | /usr/bin/cut -d : -f 1)"
ExecStop=/usr/bin/sh -c "/sbin/swapoff $(/sbin/losetup -j ${SWAPFILE} | /usr/bin/cut -d : -f 1)"
ExecStopPost=/usr/bin/sh -c "/sbin/losetup -d $(/sbin/losetup -j ${SWAPFILE} | /usr/bin/cut -d : -f 1)"
[Install]
WantedBy=multi-user.target

vars_main.yml

swap_file: /swapfile

突然のコメント失礼します。
細かい点で恐縮ですが、- name: carete swapfileは- name: create swapfileが正しいのでは無いかと思います。