node-zone-controller

A Kubernetes controller that automatically applies zone labels to nodes based on custom label.

Overview

This controller watches for nodes with the altinity.cloud/auto-zone label and automatically applies the standard Kubernetes zone labels to those nodes. This is useful for environments where nodes need custom zone assignment that differs from the cloud provider's default zone detection.

How it Works

The controller continuously monitors all nodes in the cluster. When it detects a node with the configured label key (default: altinity.cloud/auto-zone), it automatically applies both current and legacy Kubernetes zone labels with the specified value.

Configuration

Label Key

The label key to watch can be configured via:

• CLI flag: --label-key="your.label/key"
• Environment variable: LABEL_KEY=your.label/key
• Default: altinity.cloud/auto-zone

Note: CLI flag takes precedence over environment variable.

Supported Labels

Input Label

• Configurable label key (default: altinity.cloud/auto-zone): The desired zone value for the node

Applied Labels

When a node has the configured input label, the controller will automatically apply:

• topology.kubernetes.io/zone: The current standard Kubernetes zone label
• failure-domain.beta.kubernetes.io/zone: The legacy zone label for backward compatibility

Examples

Using default label key

To assign a node to zone eu-central-1a:

kubectl label node <node-name> altinity.cloud/auto-zone=eu-central-1a

Using custom label key

To use a custom label key via environment variable:

export LABEL_KEY=mycompany.io/zone
# Then start the controller

Or via CLI flag:

./controller --label-key="mycompany.io/zone"

Then label your nodes:

kubectl label node <node-name> mycompany.io/zone=us-west-2a

The controller will automatically apply:

• topology.kubernetes.io/zone=us-west-2a
• failure-domain.beta.kubernetes.io/zone=us-west-2a

Deployment

Deploy the controller using the provided manifests:

kubectl apply -f https://raw.githubusercontent.com/Altinity/node-zone-controller/refs/heads/main/deploy/deploy.yaml

This will create:

• A deployment running the controller
• RBAC permissions for the controller to read and patch nodes