fix: autoscaler use target's namespace if specified

[dblate]

What type of PR is this?

/kind bug

What this PR does / why we need it: When the namespace of the modelserving pod differs from that of the autoscaler, the namespace corresponding to the modelserving pod is used first to ensure the pod is correctly located.

Which issue(s) this PR fixes:
Fixes autoscaler, use target's namespace if specified

Special notes for your reviewer:

Does this PR introduce a user-facing change?: NONE

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[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a bug in the autoscaler's metric collection logic. It ensures that the autoscaler correctly identifies and uses the namespace of the target modelserving pod, rather than solely relying on the autoscaling policy binding's namespace. This change is crucial for scenarios where the target pod resides in a different namespace than the autoscaler itself, preventing incorrect pod location and ensuring accurate metric collection.

Highlights

• Namespace Resolution: Modified the MetricCollector initialization to prioritize the target's specified namespace for metric collection. If the target's namespace is not explicitly set, it defaults to the autoscaling policy binding's namespace.

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Changelog

• pkg/autoscaler/autoscaler/metric_collector.go
  • Updated the logic for determining the namespace used by the MetricCollector to prioritize the target's namespace.

Activity

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[Copilot]

Pull request overview

Updates autoscaler metric collection to correctly locate model-serving pods when the autoscaler’s namespace differs from the target workload’s namespace by preferring the target’s explicitly specified namespace.

Changes:

• Derive the metric-collection namespace from target.TargetRef.Namespace when set.
• Fall back to binding.Namespace when the target reference doesn’t specify a namespace.

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[gemini-code-assist]

Code Review

This pull request modifies pkg/autoscaler/autoscaler/metric_collector.go to correctly determine the namespace for metric collection, prioritizing the namespace specified in the target.TargetRef and falling back to the AutoscalingPolicyBinding's namespace. While this change aligns with the expectation that targets can exist in different namespaces, it introduces a significant security risk related to cross-namespace access control. Specifically, the NewMetricCollector function now accepts a namespace from the target reference without verifying it against the binding's namespace, potentially allowing unauthorized users to scrape metrics from pods in namespaces they should not have access to. It is recommended to add a validation check to ensure the target namespace matches the binding's namespace or implement a robust authorization mechanism for cross-namespace references.

[gemini-code-assist]

The introduction of target.TargetRef.Namespace as a source for the collection namespace without validation creates a Broken Access Control vulnerability. An attacker who can create an AutoscalingPolicyBinding in one namespace can now target and collect metrics from pods in any other namespace across the cluster. Since the autoscaler controller typically operates with high privileges, this allows unauthorized cross-namespace data access. You should ensure that the target namespace is either empty or explicitly matches the namespace of the binding.

[hzxuzhonghu]

The target cannot be set a namespace != binding, i think we can validate it in the webhook, and not change this palce

[dblate]

The target cannot be set a namespace != binding, i think we can validate it in the webhook, and not change this palce

If the target cannot be set a namespace != binding, I have a scenario and would like to ask for advice on the practical approach:

• The modelserving controller and autoscaler controller are deployed in namespace A.

• The modelserving CRD is deployed in namespace B.

• I want to deploy the autoscaler CRD to monitor and scale the modelserving related pods in namespace B.

• Should I also deploy the autoscaler CRD in namespace B? Is this supported(autoscaler CRD deployed in a different namespace from it's controller)? I tried it and it seems that it cannot monitor metrics.

[hzxuzhonghu]

The controller can be deployed in any namespace, it has nothing to do with the api object.

if modelserving in namespace A, you have to create AutoscalingPolicy and Binding in namespace A

[LiZhenCheng9527]

@dblate Please update this PR