Configuring Swap Memory on Ubuntu Using Ansible

If we maintain a Linux machine with a low memory capacity while we are required to run an application with high memory consumption, enabling swap memory is an option. Ansible can be utilized as a helper tool to automate the creation of swap memory. A swap file can be allocated in the available storage of the machine. The swap file then can be assigned as a swap memory.

Firstly, we should prepare the inventory file. The following snippet is an example, you must provide your own configuration.

[server]
192.168.1.2

[server:vars]
ansible_user=root
ansible_ssh_private_key_file=~/.ssh/id_rsa

Secondly, we need to prepare the task file that contains not only the tasks but also some variables and connection information. For instance, we set /swapfile as the name of our swap file. We also set the swap memory size to 2GB and the swappiness level to 60.

- hosts: server
  become: true
  vars:
    swap_vars:
      size: 2G
      swappiness: 60

For simplicity, we only check the existence of /swapfile for continuing the swap memory creation. The steps are as follows:

1. Verify that /swapfile doesn't exist
2. Fail the process if /swapfile exists
3. Allocate /swapfile as a swap file
4. Change the permission of /swapfile into 600
5. Create a swap area on the swap file
6. Activate the swap file as a swap memory
7. Make the activation permanent
8. Set the swappiness level of the swap memory
9. Make the swappiness level permanent

tasks:
    - name: Check whether "/swapfile" exists
      register: idCheckSwap
      stat:
        path: /swapfile

    - name: Fail it if "/swapfile" exists
      fail:
        msg: Swap file exists
      when: idCheckSwap.stat.exists == true

    - name: Allocate the swap file
      shell: fallocate -l {{ swap_vars.size }} /swapfile

    - name: Change permission of the swap file
      file:
        path: /swapfile
        mode: 600
    
    - name: Create a swap area on the swap file
      shell: mkswap /swapfile
    
    - name: Activate the swap file as a swap memory
      shell: swapon /swapfile
    
    - name: Append configuration in /etc/fstab
      shell: echo "\n/swapfile swap swap defaults 0 0\n" >> /etc/fstab
    
    - name: Set swappiness level
      shell: sysctl vm.swappiness={{ swap_vars.swappiness }}
    
    - name: Append configuration in /etc/sysctl.conf
      shell: echo "\nvm.swappiness={{ swap_vars.swappiness }}\n" >> /etc/sysctl.conf