A water utility asks which Kubernetes extension mechanism adds custom cluster APIs, as distinct from CNI, CSI, or CRI node plugins?
Select an answer to reveal the explanation.
Short Explanation
CNI/CSI/CRI are the “plugs under the hood” for network, disk, and containers. CRDs are how you teach the API server brand-new nouns—like BackupSchedule—that kubectl can get and apply. Different layer of the stack.
Full Explanation
CustomResourceDefinitions extend the Kubernetes API surface with new kinds and API groups. CNI, CSI, and CRI are node/cluster plugin interfaces for networking, storage, and runtimes; they do not themselves define arbitrary custom REST resources. Operators often install CRDs alongside controllers, but the API extension mechanism is the CRD.