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Node Readiness Controller

A Kubernetes controller that provides fine-grained, declarative readiness for nodes. It ensures nodes only accept workloads when all required components (e.g., network agents, GPU drivers, storage drivers, or custom health-checks) are fully ready on the node.

Use it to orchestrate complex bootstrap steps in your node-init workflow, enforce node health, and improve workload reliability.

What is Node Readiness Controller?

The Node Readiness Controller extends Kubernetes’ node readiness model by allowing you to define additional pre-requisites for nodes (as readiness rules) based on node conditions. It automatically manages node taints to prevent scheduling until all specified conditions are satisfied.

Why This Project?

Kubernetes nodes have a simple “Ready” condition. Modern workloads need more critical infrastructure dependencies before they can run.

With this controller you can:

  • Define custom readiness for your workloads
  • Automatically taint and untaint nodes based on condition status
  • Support continuous readiness enforcement to block scheduling for fuse break scenarios
  • Integrate with existing problem-detectors like NPD or any custom daemons/node plugins for reporting readiness

Key Features

  • Multi-condition Rules: Define rules that require ALL specified conditions to be satisfied
  • Flexible Enforcement: Support for bootstrap-only and continuous enforcement modes
  • Conflict Prevention: Validation webhook prevents conflicting taint configurations
  • Dry Run Mode: Preview rule impact before applying changes
  • Comprehensive Status: Detailed observability into rule evaluation and node readiness status
  • Node Targeting: Use label selectors to target specific node types
  • Bootstrap Completion Tracking: Prevents re-evaluation once bootstrap conditions are met

Demo

Node Readiness Controller in Kind cluster

Node Readiness Demo

Example Rule

apiVersion: readiness.node.x-k8s.io/v1alpha1
kind: NodeReadinessRule
metadata:
  name: network-readiness-rule
spec:
  conditions:
    - type: "example.com/CNIReady"
      requiredStatus: "True"
  taint:
    key: "readiness.k8s.io/NetworkReady"
    effect: "NoSchedule"
    value: "pending"
  enforcementMode: "bootstrap-only"
  nodeSelector:
    matchLabels:
      node-role.kubernetes.io/worker: ""

Getting Involved

If you’re interested in participating in future discussions or development related to Node Readiness Controller, you can reach the maintainers of the project at:

Open Issues / PRs / Discussions here:

See the Kubernetes community on the community page. You can also engage with SIG Node at #sig-node and mailing list.

Project Status

This project is currently in alpha. The API may change in future releases.