Add swap memory with ansible

Question

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

Answer 1

I based my take on the great Ashley's answer (please upvote it!) and added the following extra features:

• global flag to manage the swap or not,
• allow changing the swap size,
• allow disabling swap,

...plus these technical improvements:

• full idempotency (only ok & skipping when nothing is changed, otherwise some changed),
• use dd instead of fallocate for compatibility with XFS fs (see this answer for more info),

Tested on Centos 7.7 with Ansible 2.9.10.

Parameters:

swap_configure: true # manage the swap or not 
swap_enable: true
swap_file_path: /swapfile
swap_file_size_mb: 4096
swappiness: 1

The code:

- name: Configure swap
  when: swap_configure | bool | default(false)
  block:

    - name: Check if swap file exists
      stat:
        path: "{{swap_file_path}}"
      register: swap_file_check
      changed_when: false

    - name: Check if swap is on
      shell: swapon --show | grep {{swap_file_path}}
      register: swap_enabled
      changed_when: false
      failed_when: false

    - name: Disable swap
      command: swapoff {{swap_file_path}}
      register: swap_disabled
      when: >
        swap_file_check.stat.exists
        and swap_enabled.rc == 0
        and (not swap_enable
             or (swap_enable and swap_file_check.stat.size != (swap_file_size_mb * 1024 * 1024)))

    - name: Delete the swap file
      file:
        path: "{{swap_file_path}}"
        state: absent
      when: not swap_enable

    - name: Configure swap
      when: swap_enable|bool
      block:

        - name: Create or change the size of swap file
          command: dd if=/dev/zero of={{swap_file_path}} count={{swap_file_size_mb}} bs=1MiB
          register: swap_file_created
          when: >
            not swap_file_check.stat.exists
            or swap_file_check.stat.size != (swap_file_size_mb * 1024 * 1024)

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

        - name: Check if swap is formatted
          shell: file {{swap_file_path}} | grep 'swap file'
          register: swap_file_is_formatted
          changed_when: false
          failed_when: false

        - name: Format swap file if it's not formatted
          command: mkswap {{swap_file_path}}
          when: swap_file_is_formatted.rc > 0 or swap_file_created.changed

        - name: Add swap entry to fstab
          mount: name=none
            src={{swap_file_path}}
            fstype=swap
            opts=sw
            passno=0
            dump=0
            state=present

        - name: Turn on swap
          shell: swapon -a
          when: swap_enabled.rc == 0 and swap_disabled.changed

        - name: Configure swappiness
          sysctl:
            name: vm.swappiness
            value: "{{ swappiness }}"
            state: present