Use prioritization on volume capacity

[toshipp]

What

We will add a mode for storage capacity tracking in #193, but it is insufficient to select the best node as of kubernetes 1.19.
By kubernetes 1.21, the Prioritization on volume capacity feature is introduced as alpha, which makes the kube-scheduler be able to select the best node which has a maximum storage capacity.

Thanks to the mode and this feature, we will be able to remove topolvm-scheduler completely.

How

• Enable the feature by feature flags
• Add tests
• Add documents

Checklist

• Finish implementation of the issue
• Test all functions
• Have enough logs to trace activities
• Notify developers of necessary actions

[toshipp]

minikube 1.22 supports k8s 1.22 beta.0 (https://github.com/kubernetes/minikube/releases/tag/v1.22.0)

[toshipp]

kind project does not release kind-node 1.22 yet, however, I can create kind-node image in local and launch a cluster.

[toshipp]

All tests with kind-node 1.22-beta.0 successfully passed!
The image is quay.io/topolvm/kind-node:v1.22.0-beta.0

[toshipp]

We realized KEP-1845 does not cover our use case.

Prioritizing nodes based on the total available capacity for dynamic provisioning PVCs

We'll wait for another KEP...

[github-actions]

This issue has been automatically marked as stale because it has not had any activity for 30 days. It will be closed in a week if no further activity occurs. Thank you for your contributions.