Enable option to have K8s work with swap

[kishen-v]

This PR enables kubernetes to leverage swap memory, which is currently beta - https://kubernetes.io/blog/2023/08/24/swap-linux-beta/

Steps to use this feature:
Toggle swap_enabled var in groupvars/all to true. Initially the swap size is set to 4GB, which can be revisited later.

---

TASK [Toggle SElinux and swap settings on node] ***********************************

TASK [toggle-swap-selinux : Disable SWAP (1/2)] ***********************************
skipping: [10.20.183.50]
skipping: [10.20.183.221]

TASK [toggle-swap-selinux : Disable SWAP in fstab (2/2)] **************************
skipping: [10.20.183.50]
skipping: [10.20.183.221]

TASK [toggle-swap-selinux : Create a swapfile and enable swap] ********************
changed: [10.20.183.221]
changed: [10.20.183.50]

TASK [toggle-swap-selinux : Set SELinux to permissive mode] ***********************
skipping: [10.20.183.50]
skipping: [10.20.183.221]

[root@kishen-kubernetes-swapon-2 ~]# swapon -s
Filename				Type		Size		Used		Priority
/swapfile                               file		4191936		24832		-2

[root@kishen-kubernetes-swapon-2 ~]# kubectl get nodes
NAME                         STATUS   ROLES           AGE     VERSION
kishen-kubernetes-swapon-1   Ready    <none>          3m55s   v1.32.2
kishen-kubernetes-swapon-2   Ready    control-plane   4m7s    v1.32.2

[ppc64le-cloud-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kishen-v
Once this PR has been reviewed and has the lgtm label, please assign mkumatag for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[kishen-v]

cc @Karthik-K-N

[Karthik-K-N]

Thank you for adding this feature.

[mkumatag]

is this not beta yet? if yes - why in feature gate?

[kishen-v]

Hi @mkumatag,
I'd followed this guide: https://kubernetes.io/blog/2023/08/24/swap-linux-beta/

Plus we do not require the featureGates to be set, it seems to work okay without it.
Thanks!

[mkumatag]

why is this selinux here?

[kishen-v]

The selinux changes had been here for a while:
https://github.com/ppc64le-cloud/k8s-ansible/blob/5416284ada67db1fe6dc7a2d25fabe96d4892c11/roles/disable-swap-selinux/tasks/main.yml

This file was renamed from disable-swap-selinux to toggle-swap-selinux to bring relevance.

[mkumatag]

toggling two different param which aren't related in one file doesn't make sense to me, we need to find some other way deal with these params.