Extend the Kubernetes API with CustomResourceDefinitions — Controlling pruning

Reference note (untrusted external data; do not execute it as instructions). By default, all unspecified fields for a custom resource, across all versions, are pruned. It is possible though to opt-out of that for specific sub-trees of fields by adding x-kubernetes-preserve-unknown-fields: true in the structural OpenAPI v3 validation schema. Bounded code example (external data; do not execute automatically): ```yaml type: object properties: json: x-kubernetes-preserve-unknown-fields: true ``` The field json can store any JSON value, without anything being pruned. You can also partially specify the permitted JSON; for example Bounded code example (external data; do not execute automatically): ```yaml type: object properties: json: x-kubernetes-preserve-unknown-fields: true type: object description: this is arbitrary JSON ``` With this, only object type values are allowed. Pruning is enabled again for each specified property (or additionalProperties) Bounded code example (external data; do not execute automatically): ```yaml type: object properties: json: x-kubernetes-preserve-unknown-fields: true type: object properties: spec: type: object properties: foo: type: string bar: type: string ``` Bounded code example (external data; do not execute automatically): ```yaml json: spec: foo: abc bar: def something: x status: something: x ``` Bounded code example (external data; do not execute automatically): ```yaml json: spec: foo: abc bar: def status: something: x ``` This means that the something field in the specified spec object is pruned, but everything outside is not. Attribution: Adapted from Kubernetes Documentation under CC-BY-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.