support PriorityClass on frontend

[khalilswdp]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Add frontend to consume api for priorityclass from backend.

Which issue(s) this PR fixes:

Related #27
Fixes #27

Special notes for your reviewer:

Just a question, was I supposed to separate PRs by making two separate branches (with separate commits only relevant for PR, like here) or make two branches that might share some code and commits: for example, I leave same previous branch and create a branch on commit where work on backend ended and branch on commit where work on frontend ended and make PRs for both? What are the best practices to follow next time?
This is the front end commits after separating them from branch previous branch (front end won't work since it requires back end changes to be present).
(Answered)

/label tide/merge-method-squash

[khalilswdp]

/assign @sanposhiho

[sanposhiho]

Just a question, ....

In most cases, I think the best way is to wait to create frontend PR until backend PR is merged.
Since the specification of a new backend API is not approved until backend PR is merged, it may need to be changed even if the front-end is developed before backend PR is merged.

But, for this feature, the API for PriorityClass should be exactly the same as the API of other resources, so I think it is okay to develop web frontend before backend PR is merged.
However, as you said, this frontend changes don't work and won't be reviewed until backend PR is merged.

[sanposhiho]

/label tide/merge-method-squash

[sanposhiho]

@khalilswdp The PR for backend API was merged.
If you rebase this branch with the latest master, you can check the behavior of this frontend change with backend.

[sanposhiho]

@khalilswdp
We created the pull request description template.
https://raw.githubusercontent.com/kubernetes-sigs/kube-scheduler-simulator/master/.github/PULL_REQUEST_TEMPLATE.md

Could you please update the pull request description in the format of this? (like #54)

[khalilswdp]

/kind feature
/label tide/merge-method-squash

[khalilswdp]

Fixes #27

[sanposhiho]

@khalilswdp Thanks for updating! 👍 I'll review it later.

[sanposhiho]

Nice contribution. 👍
I think almost all the changes are okay.

[sanposhiho]

added small comments :)

[sanposhiho]

nits:

Suggested change

	name: default-priority-class
	name: priority-class

[sanposhiho]

nits: If my English is strange, please change it to a proper English sentence. (I'm not a native speaker.)

Suggested change

	description: "Default priority class for all pods"
	description: "This is a template priority class for all pods"

[khalilswdp]

I am not a native english speaker myself, but it look good to me

[sanposhiho]

There are two Priority classes from the beginning. ("system-cluster-critical" and "system-node-critical")

Kubernetes already ships with two PriorityClasses: system-cluster-critical and system-node-critical. These are common classes and are used to ensure that critical components are always scheduled first.
https://kubernetes.io/docs/concepts/scheduling-eviction/pod-priority-preemption/

Suggested change

	// if store.count = 0, name suffix is 1.
	targetTemplate = priorityclassTemplate((store.count + 1).toString());
	// if store.count = 2, name suffix is 1.
	targetTemplate = priorityclassTemplate((store.count - 1).toString());

[khalilswdp]

Hi @sanposhiho I followed the proposed suggestions

[sanposhiho]

I approve this change. Thanks @khalilswdp!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: khalilswdp, sanposhiho

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