Inconsistent behaviour within VPA components regarding targetRef

[adrianmoisey]

Which component are you using?:

vertical-pod-autoscaler

What version of the component are you using?:

Component version: 1.1.2

What k8s version are you using (kubectl version)?:

Various: 1.28 and 1.30

What environment is this in?:

Any. I've reproduced in GKE, AWS (kOps) and Kind.

What did you expect to happen?:

When setting a targetRef with a lowecase kind, the VPA admission-controller doesn't match the new Pods.
However, the updater component does match the Pod.

What happened instead?:

Pod wasn't matched in the admission-controller

How to reproduce it (as minimally and precisely as possible):

Use the hamster example in this repo, and replace "Deployment" with "deployment"

Anything else we need to know?:

1. This might be related to Vertical Pod Autoscaler is not recreating pods at runtime #6915
2. The HPA accepts kind with a lowercase kind ie: deployment

/area vertical-pod-autoscaler
/assign

[voelzmo]

/triage accepted

[raywainman]

Some notes:

• In the admission controller, we assume "Deployment" here when fetching the label selector, however I think if you use deployment here, it will fail this check but still ultimately work because it implements the /scale subresource. So here you would be doing additional lookups against API server.
• I wonder if we ultimately fail the matching here when we compare the pod's owner (which could be Deployment) with the VPA which is deployment.

[raywainman]

I don't fully understand though why there is a difference between admission-controller and updater. They both use the same logic.

Here is the logic for the Updater, it is using the same mechanics as the admission-controller.

[adrianmoisey]

• I wonder if we ultimately fail the matching here when we compare the pod's owner (which could be Deployment) with the VPA which is deployment.

Yup, this is where I think the issue lies.
I made a PR to use the RESTMapper (similar to the HPA) here: #6929
I'm unsure if it's the right approach though.