VPA assigns `minAllowed.memory` instead of actual recommendation when restarting Prometheus pod if `Limitrange` is set

[MatteoMori8]

Which component are you using?:

• vertical-pod-autoscaler

What version of the component are you using?:

• 1.2.1

Component version:

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

Server Version: v1.29.8-eks

What environment is this in?:

• AWS - eks

What did you expect to happen?: I expected VPA's AdmissionController to patch my Prometheus pod with a request.memory value equal to the memory target recommendation

What happened instead?: Instead, the new pod got deployed with the following:

• limit.memory got halved
• request.memory has been assigned the value that I specified as minAllowed.memory from the VPA object itself

On the other hand, CPU got updated correctly

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

VPA object

```yaml apiVersion: autoscaling.k8s.io/v1 kind: VerticalPodAutoscaler metadata: name: prometheus-test spec: resourcePolicy: containerPolicies: - containerName: prometheus controlledResources: - cpu - memory controlledValues: RequestsAndLimits maxAllowed: memory: 30Gi minAllowed: cpu: 100m memory: 500Mi - containerName: thanos-sidecar controlledResources: - cpu - memory controlledValues: RequestsAndLimits maxAllowed: memory: 20Gi minAllowed: memory: 100Mi targetRef: apiVersion: apps/v1 kind: StatefulSet name: prometheus-test updatePolicy: updateMode: "Initial" ```

LimitRange

```yaml apiVersion: v1 kind: LimitRange metadata: name: limits spec: limits: - max: memory: 60Gi min: cpu: 1m memory: 50Mi type: Pod - default: memory: 512Mi defaultRequest: cpu: 20m memory: 256Mi min: memory: 50Mi type: Container ```

Anything else we need to know?:

We talked this out on the #sig-autoscaling Slack channel and it turns out that by deleting the LimitRange, VPA goes back on track and manages memory in the appropriate way.

Personally I do not know if this is a bug or an opportunity to enhance the docs but we thought it could be good to raise an Issue about it

[adrianmoisey]

/area vertical-pod-autoscaler

[adrianmoisey]

/assign

[adrianmoisey]

Does the Prometheus statefulset define any resources?

[adrianmoisey]

Instead, the new pod got deployed with the following:

• limit.memory got halved
• request.memory has been assigned the value that I specified as minAllowed.memory from the VPA object itself

Which container in the Pod got these set?