Ansible: how to add swap memory on your Linux box

If you are not familiar with ansible, you might want to take a look at our previous post.  So here’s a problem. If you have, say, Amazon EC2 instance or Rackspace Cloud server, you might want to add swap memory. You can do do it by running the following commands:

sudo dd if=/dev/zero of=/mnt/4GB.swap bs=4096 count=1048576
sudo chmod 600 /mnt/4GBB.swap
sudo mkswap /mnt/4GB.swap
swapon /mnt/4GB.swap

and add this line to /etc/fstab:

/mnt/512MiB.swap  none  swap  sw  0 0

If you have one server it’s acceptable, but if you have a lot of them, it would be much easier  to use ansible. We will use the how-to by Rackspace on how to create swap file. (We assume you have a user account ‘devops’ which is able to log in using SSH key  as well as to run commands as root via sudo. If need need check our blog entry about ansible mentioned earlier).

- hosts: web001
- name: create the file to be used for swap
command: fallocate -l 4G /mnt/4GB.swap

- name: format the file for swap
command: mkswap /mnt/4GB.swap

- name: change swap file permissions
file: path=/mnt/4GB.swap owner=root group=root mode=0600

- name: add the file to the system as a swap file
command: swapon /mnt/4GB.swap

- name: write swap entry in fstab
mount: name=none src=/mnt/4GB.swap fstype=swap opts=sw passno=0 dump=0 state=present

If you get this error message:

fallocate: /mnt/4GB.swap: fallocate failed: Operation not supported

use dd instead:

sudo dd if=/dev/zero of=./4GB.swap bs=4096 count=1048576

Run create a swap file run:

ansible-playbook add_swap.yml -u devops -s -v --check

Remove –check parameter to apply changes. And that’s it.

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