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OLM Ownership Enforcement for ClusterExtensions

In OLM, a Kubernetes resource can only be owned by a single ClusterExtension at a time. This ensures that resources within a Kubernetes cluster are managed consistently and prevents conflicts between multiple ClusterExtensions attempting to control the same resource.

Key Concept: Single Ownership

The core principle enforced by OLM is that each resource can only have one ClusterExtension as its owner. This prevents overlapping or conflicting management by multiple ClusterExtensions, ensuring that each resource is uniquely associated with only one operator bundle.

Implications of Single Ownership

1. Operator Bundles That Provide a CRD Can Only Be Installed Once

Operator bundles provide CustomResourceDefinitions (CRDs), which are part of a ClusterExtension. This means a bundle can only be installed once in a cluster. Attempting to install another bundle that provides the same CRDs will result in a failure, as each custom resource can have only one ClusterExtension as its owner.

2. ClusterExtensions Cannot Share Objects

OLM's single-owner policy means that ClusterExtensions cannot share ownership of any resources. If one ClusterExtension manages a specific resource (e.g., a Deployment, CustomResourceDefinition, or Service), another ClusterExtension cannot claim ownership of the same resource. Any attempt to do so will be blocked by the system.

Error Messages

When a conflict occurs due to multiple ClusterExtensions attempting to manage the same resource, operator-controller will return a clear error message, indicating the ownership conflict.

  • Example Error: 
    CustomResourceDefinition 'logfilemetricexporters.logging.kubernetes.io' already exists in namespace 'kubernetes-logging' and cannot be managed by operator-controller

This error message signals that the resource is already being managed by another ClusterExtension and cannot be reassigned or "shared."

What This Means for You

  • Uniqueness of Operator Bundles: Ensure that operator bundles providing the same CRDs are not installed more than once. This can prevent potential installation failures due to ownership conflicts.
  • Avoid Resource Sharing: If you need different ClusterExtensions to interact with similar resources, ensure they are managing separate resources. ClusterExtensions cannot jointly manage the same resource due to the single-owner enforcement.