Add swap memory with ansible

I'm working on a project where having swap memory on my servers is a needed to avoid some python long running processes to go out of memory and realized for the first time that my ubuntu vagrant boxes and AWS ubuntu instances didn't already have one set up.

In https://github.com/ansible/ansible/issues/5241 a possible built in solution was discussed but never implemented, so I'm guessing this should be a pretty common task to automatize.

How would you set up a file based swap memory with ansible in an idempotent way? What modules or variables does ansible provide help with this setup (like ansible_swaptotal_mb variable) ?

Solution

This is my current solution:

- name: Create swap file
  command: dd if=/dev/zero of={{ swap_file_path }} bs=1024 count={{ swap_file_size_mb }}k
           creates="{{ swap_file_path }}"
  tags:
    - swap.file.create


- name: Change swap file permissions
  file: path="{{ swap_file_path }}"
        owner=root
        group=root
        mode=0600
  tags:
    - swap.file.permissions


- name: "Check swap file type"
  command: file {{ swap_file_path }}
  register: swapfile
  tags:
    - swap.file.mkswap


- name: Make swap file
  command: "sudo mkswap {{ swap_file_path }}"
  when: swapfile.stdout.find('swap file') == -1
  tags:
    - swap.file.mkswap


- name: Write swap entry in fstab
  mount: name=none
         src={{ swap_file_path }}
         fstype=swap
         opts=sw
         passno=0
         dump=0
         state=present
  tags:
    - swap.fstab


- name: Mount swap
  command: "swapon {{ swap_file_path }}"
  when: ansible_swaptotal_mb < 1
  tags:
    - swap.file.swapon