A library function to calculate Pod resource utilization

[alculquicondor]

What would you like to be added?

We currently have this function

kubernetes/pkg/api/v1/resource/helpers.go

Line 50 in ae02f87

func PodRequests(pod *v1.Pod, opts PodResourcesOptions) v1.ResourceList {

It is used by both kube-scheduler and kubelet to calculate resource utilization.

It would be useful to have it in a library package, such as k8s.io/component-helpers.

Why is this needed?

Multiple downstream projects need to calculate resource utilization, for quota management, billing, etc.

The resource calculation might always change, so these projects always have to catch up. The most recent change that I'm aware of is sidecar containers.

[alculquicondor]

/sig scheduling

[alculquicondor]

cc @liggitt for any concerns

[bobbypage]

+1, I think this would be helpful to have as a generic library function to generate resource requirements for pods.

[kannon92]

/sig node

cc @SergeyKanzhelev @gjkim42

[kannon92]

I think the hard part of this would be the same as why we can't move validation into staging. Some of those fields may not belong in staging like pod validation opts.

[alculquicondor]

This one is easier. It's based on versioned types.

[AxeZhan]

I think the hard part of this would be the same as why we can't move validation into staging. Some of those fields may not belong in staging like pod validation opts.

+1
This function relies /pkg/api/v1/pod and PodResourcesOptions and both of them are not in staging.

I'm +1 for having this but I think maybe we need to move both /pkg/api/v1/pod and /pkg/api/v1/resource to component-helpers

[SergeyKanzhelev]

We also wanted to implement this: #115643

Those are not mutually exclusive, just pointing that for many use cases reading pod status may be a better idea.

[SergeyKanzhelev]

btw, this function by itself was a result of the big effort: #115367

[AxeZhan]

I think kubectl also faces this problem:

kubernetes/staging/src/k8s.io/kubectl/pkg/util/resource/resource.go

Line 40 in 53870af

func podRequests(pod *corev1.Pod) corev1.ResourceList {

and also in admission:

kubernetes/plugin/pkg/admission/limitranger/admission.go

Line 560 in 53870af

func podRequests(pod *api.Pod, opts podResourcesOptions) api.ResourceList {

We now maintain this same function in three different places, I'll try if we can merge these three function into one in pkg component-helpers.

[ffromani]

/triage accepted

Reusing the same code in scheduler and kubelet would be highly beneficial in quite a few flows

[AxeZhan]

/assign

[AxeZhan]

I've created #124609 to simply move both /pkg/api/v1/pod and /pkg/api/v1/resource to component-helpers.

To fully solve this problem, we need to replace the function pointed out in #124537 (comment) with the function in component-helpers.

I tend to replace them after #124609 if we all agree the movement, to reduce the complexity of #124609.