Keda Admission Webhook rejects ScaledObject requests that use Range Limit

[ben-dov]

Report

Keda Admission Webhook fails ScaledObject requests with memory/CPU triggers that don't have memory/CPU request defined although Range Limit is defined in the namespace.
This bug report is similar to #4802 , but if Range Limit is defined with defaults limit and requests for CPU and memory, then Admission Webhook should not reject workload that define only limit, or only requests, or a combination of both.

Expected Behavior

Based on Kubernetes documentation for default memory and CPU, ScaledObject with memory and/or CPU triggers of a deployment with no requests or limits on the relevant scaler, should not be rejected by Keda Admission Webhook if a Range Limit is define with default limit and requests (of the relevant memory/CPU metric)

Actual Behavior

Keda Admission Webhook rejects ScaledObject request with:
admission webhook ... denied the request: the scaledobject has a memory trigger but the container ... doesn't have the memory request defined

Steps to Reproduce the Problem

1. Create a Range Limit with default limit and request of memory and CPU.
2. Create a Deployment with no resource requests or limit (e.g CPU)
3. Create a ScaledObject with CPU scaler that points to the Deployment.
4. Get an error message on apply.

Logs from KEDA operator

No response

KEDA Version

2.12.1

Kubernetes Version

1.26

Platform

Amazon Web Services

Scaler Details

Memory, CPU

Anything else?

No response

[JorTurFer]

Yeah, makes sense totally. The admission webhook should check if there is any default value set by Range Limit.
Are you willing to include the validation?

[ben-dov]

Unfortunately I don't have any experience in Go 😅

[asoundarya96]

@JorTurFer i would like to work on this issue

[JorTurFer]

Nice!
Let me assign it to you ❤️

[Bhargav-InfraCloud]

@asoundarya96 Are you working on this? Else, I want to give it a try.

[zroubalik]

@Bhargav-InfraCloud I think you can proceed with this, we plan to do a new release later this week, we can include this if you are able to tackle it soon :)

[Bhargav-InfraCloud]

Sure @zroubalik. Thanks! Working on it.

[Bhargav-InfraCloud]

Hi team,
Please review the following PRs. Thanks!

1. fix(ScaledObject): Check default limits from LimitRange for ScaledObject validations #5377
2. feat(ClusterRole): Add RBAC rule to allow access to LimitRange charts#588
3. docs(scalers): Update cpu and memory scaler docs for validating requests/limits from LimitRange keda-docs#1296