Kubernetes CRDs Without Controllers Exposed as Overpriced YAML Filing Cabinets

Kubernetes' extensibility is rooted in Custom Resources, Custom Resource Definitions, and Controllers, allowing companies to define their own APIs and solve domain-specific problems. By creating a Custom Resource Definition, users can introduce new object types, such as databases or machine learning models, which are stored by Kubernetes but require a controller to become functional. The controller watches the custom resource, compares the desired state with the actual state, and reconciles the difference, creating or updating resources as needed. This loop ensures strong reconciliation guarantees and declarative behavior. Industry leaders like Istio, ArgoCD, and Prometheus Operator utilize this framework to extend Kubernetes' capabilities. Understanding this concept is crucial for leveraging Kubernetes beyond basic deployment, enabling users to manage complex lifecycles and build custom platforms. By recognizing the distinction between Custom Resources and controllers, developers can harness the full potential of Kubernetes, driving innovation and efficiency in the industry.