Add NodeMetadata scoring plugin

[alikhil]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR introduces new score plugin which allows you to influence scheduling decisions based on custom node metadata. It supports two types of metadata:

1. Numeric values - Score nodes based on numeric labels/annotations
2. Timestamps - Score nodes based on timestamp labels/annotations

Use Cases

1. Cost Optimization - Prefer cheaper nodes
2. Hardware Generation - Prefer newer or older hardware
3. Maintenance Windows - Avoid recently maintained or prefer well-maintained nodes
4. Custom Priorities - Implement business-specific node prioritization
5. Node Aging - Distribute workloads based on node age
6. Performance Tiers - Score nodes by performance benchmarks

Behavior Notes

• If a node doesn't have the specified metadata key, it receives a score of 0 (lowest)
• Scores are normalized to the range [0, 100] (framework.MinNodeScore to framework.MaxNodeScore)
• The plugin can be combined with other scoring plugins using weighted scores
• Invalid metadata values (e.g., unparseable timestamps) result in a score of 0 for that node

Arguments

The plugin accepts the following configuration parameters:

Parameter	Type	Required	Description
metadataKey	string	Yes	The name of the label or annotation to use for scoring
metadataSource	string	Yes	Where to read metadata from: "Label" or "Annotation"
metadataType	string	Yes	Type of metadata value: "Number" or "Timestamp"
scoringStrategy	string	Yes	How to score nodes (see below)
timestampFormat	string	Conditional	Go time format string (required when metadataType is "Timestamp")

Example Score by Last Update Time (Newest Timestamp)

Prefer nodes that were updated most recently:

apiVersion: kubescheduler.config.k8s.io/v1
kind: KubeSchedulerConfiguration
profiles:
  - schedulerName: default-scheduler
    plugins:
      score:
        enabled:
          - name: NodeMetadata
    pluginConfig:
      - name: NodeMetadata
        args:
          metadataKey: "node.example.com/last-maintenance"
          metadataSource: "Annotation"
          metadataType: "Timestamp"
          scoringStrategy: "Newest"
          timestampFormat: "2006-01-02T15:04:05Z07:00"  # RFC3339

Node annotations:

apiVersion: v1
kind: Node
metadata:
  name: node1
  annotations:
    node.example.com/last-maintenance: "2025-12-01T10:00:00Z"
---
apiVersion: v1
kind: Node
metadata:
  name: node2
  annotations:
    node.example.com/last-maintenance: "2025-12-03T10:00:00Z"

Result: node2 gets a higher score than node1 (more recently maintained).

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Add NodeMetadata scoring plugin

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[ffromani]

/cc

[PiotrProkop]

can you add a bit longer description? What does this plugin tries to do? What are the usecases?

[alikhil]

@PiotrProkop I have added more details to the PR description. You can also refer to the plugin’s README.md for additional information.

[alikhil]

Friendly ping when you have a moment — I’d appreciate any feedback. Thanks!

[josqu4red]

Hello, co-owner of the fork here, can we do anything to help get this change reviewed? Thanks.