Inventory and Transport Spaces

  1. Inventory Management: It maintains a registry of all Workload Execution Clusters (WECs) available in the system.
  2. Transport Facilitation: It handles the movement of workloads from Workload Description Spaces (WDSes) to the appropriate WECs.

What is an ITS?

An ITS is a space (a Kubernetes-like API server with storage) that:

  • Holds inventory information about all registered WECs using ManagedCluster.v1.cluster.open-cluster-management.io objects
  • Contains a “customization-properties” namespace with ConfigMaps carrying additional properties for each WEC
  • Manages mailbox namespaces that correspond 1:1 with each WEC, holding ManifestWork objects
  • Runs the OCM (Open Cluster Management) Cluster Manager to synchronize objects with the WECs

Creating an ITS

An ITS can be created in several ways:

Using the KubeStellar Core Helm Chart

The recommended approach is to use the KubeStellar Core Chart:

helm upgrade --install ks-core oci://ghcr.io/kubestellar/kubestellar/core-chart \
  --set-json='ITSes=[{"name":"its1", "type":"vcluster"}]'

You can customize your ITS by specifying:

  • name: A unique name for the ITS
  • type:
    • vcluster (default): Creates a virtual cluster
    • host: Uses the KubeFlex hosting cluster itself
    • external: Uses an external cluster
  • install_clusteradm: true (default) or false to control OCM installation

Using the KubeFlex CLI

You can also create an ITS using the KubeFlex CLI:

kflex create its1 --type vcluster -p ocm

KubeFlex Hosting Cluster as ITS

The KubeFlex hosting cluster can be configured to act as an ITS by specifying type: host when creating the ITS:

helm upgrade --install ks-core oci://ghcr.io/kubestellar/kubestellar/core-chart \
  --set-json='ITSes=[{"name":"its1", "type":"host"}]'

This approach:

  • Avoids creating a separate virtual cluster
  • Simplifies the architecture by reusing the hosting cluster
  • Makes the ITS directly accessible through the hosting cluster’s API server

Important Note on ITS Registration

Creating an ITS includes installing the relevant OCM (Open Cluster Management) machinery in it. However, registering the ITS as a KubeFlex control plane is a separate step that happens automatically when using the Core Helm Chart or KubeFlex CLI with the appropriate parameters.

Architecture and Components

The ITS runs the OCM Cluster Manager, which:

  • Accepts registrations from WECs through the OCM registration agent
  • Manages the distribution of workloads to WECs
  • Maintains status information from the WECs
  • Creates and manages mailbox namespaces for each registered WEC