Workload Execution Clusters

• What is a WEC?
• Creating a WEC
  • Using Kind (for development/testing)
  • Using K3d (for development/testing)
  • Using MicroShift (for edge deployments)
  • Using Production Kubernetes Distributions
• Registering a WEC
• Labeling WECs
• WEC Customization Properties
• WEC Status and Monitoring
• Workload Transformation Workload Execution Clusters (WECs) are the Kubernetes clusters where KubeStellar deploys and runs the workloads defined in the Workload Description Spaces (WDSes).

What is a WEC?

A WEC is a standard Kubernetes cluster that:

• Runs the actual workloads distributed by KubeStellar
• Has the OCM Agent (klusterlet) installed for communication with the ITS
• Is registered with an Inventory and Transport Space (ITS)
• May have specific characteristics (location, resources, capabilities) that make it suitable for particular workloads

Requirements for a WEC

For a Kubernetes cluster to function as a WEC in the KubeStellar ecosystem, it must:

1. Have network connectivity to the Inventory and Transport Space (ITS)
2. Be a valid Kubernetes cluster with a working control plane
3. Have the OCM Agent installed for integration with KubeStellar
4. Be registered with an ITS to receive workloads

Creating a WEC

You can use any existing Kubernetes cluster as a WEC, or create a new using your preferred method:

Using Kind (for development/testing)

kind create cluster --name cluster1
kubectl config rename-context kind-cluster1 cluster1

Using K3d (for development/testing)

k3d cluster create -p "9443:443@loadbalancer" cluster1
kubectl config rename-context k3d-cluster1 cluster1

Using MicroShift (for edge deployments)

For resource-constrained environments like edge devices, you can use MicroShift:

# Instructions for setting up MicroShift can be found at
# https://community.ibm.com/community/user/cloud/blogs/alexei-karve/2021/11/28/microshift-4

Using Production Kubernetes Distributions

For production environments, consider using:

• Red Hat OpenShift
• Amazon EKS
• Google GKE
• Microsoft AKS
• Any conformant Kubernetes distribution

Registering a WEC

After creating your cluster, you need to register it with an ITS. This process installs the OCM Agent and establishes the communication channel.

# Get the join command from the ITS
clusteradm --context its1 get token
 
# Execute the join command with your WEC name
clusteradm join --hub-token <token> --hub-apiserver <api-server-url> --cluster-name cluster1 --context cluster1
 
# Accept the registration on the ITS side
clusteradm --context its1 accept --clusters cluster1

For detailed registration instructions, see WEC Registration.

Labeling WECs

After registration, you should label your WEC to make it selectable by BindingPolicies:

kubectl --context its1 label managedcluster cluster1 location-group=edge name=cluster1

These labels can represent any characteristics relevant to your workload placement decisions:

• Geographic location (region=us-east, location=edge)
• Hardware capabilities (gpu=true, cpu-architecture=arm64)
• Environment type (environment=production, environment=development)
• Compliance requirements (pci-dss=compliant, hipaa=compliant)
• Custom organizational labels (team=retail, business-unit=finance)

WEC Customization Properties

For each WEC, you can define additional properties in a ConfigMap stored in the “customization-properties” namespace of the ITS. These properties can be used for rule-based transformations of workloads.

WEC Status and Monitoring

You can check the status of your registered WECs:

kubectl --context its1 get managedclusters

Workload Transformation

KubeStellar performs transformations on workloads before they are deployed to WECs:

1. Generic transformations that apply to all workloads
2. Rule-based customizations that adapt workloads to specific WEC characteristics

For more information, see Transforming Desired State.