[terraform] Add k3s setup for tests

[nandajavarma]

Description

This PR adds a very rough single-cluster setup for k3s. We are adding this for consistency with Azure, AWS and GCP setups so we can consistently run the tests. We do not recommend users to use this because the underlying module still make use of k3sup and we have plans to move to k3s before suggesting this as a solution. Hence we have not included a Readme with this directory.

Related Issue(s)

Fixes #12866

How to test

• Go to the directory install/infra/single-cluster/k3s.
• Edit main.tf to have the right bucket name.
• Edit terraform.tfvars to right parameters for the cluster.
  Then run:

make init
make plan
make apply
# After testing, make sure you cleanup with:
make destroy

Release Notes

NONE

Documentation

Werft options:

• /werft with-preview

[github-actions]

⚠️ Hey reviewer! BE CAREFUL ⚠️
Review the code before opening in your Gitpod. .gitpod.yml was changed and it might be harmful.

[adrienthebo]

Ack, didn't submit this review! Sorry for the delay!

The only major change is switching a couple of cases from var.credentials to local.credentials_path. Also it seems like switching these variables around to pass credentials as a variable while introducing credentials_path is incurring more pain than I expected; if it continues to hurt we can just revert that change and pass around a file path.

There's some touch ups we can land around make output but we can address that in another PR.

Since this has been taking longer to review/merge than I like I'm approving this now, amend as you see fit. Thanks for your patience!

/hold for above, merge at your discretion

[adrienthebo]

Suggested change

	credentials = var.credentials_path
	kubeconfig = var.kubeconfig
	dns_sa_creds = var.credentials_path
	credentials = local.credentials
	kubeconfig = var.kubeconfig
	dns_sa_creds = local.credentials

[nandajavarma]

The k3s module expects the file path and not the JSON content itself. This change would break the module

[adrienthebo]

thought: We should look into using terraform init -backend-config so that the GCS backend can be adjusted without having to amend a version controlled file.

No action needed.

[nandajavarma]

/unhold