How can I validate Custom Resource Definitions in Kubernetes?

How can I validate Custom Resource Definitions in Kubernetes?

You can validate Custom Resource Definitions (CRDs) in Kubernetes by using OpenAPI v3 schemas. This allows you to define validation rules for your custom resources.

Can you give me an example of a CRD with validation?

Sure! Here's a simple example:

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: myresources.example.com
spec:
  group: example.com
  versions:
    - name: v1
      served: true
      storage: true
      schema:
        openAPIV3Schema:
          type: object
          properties:
            spec:
              type: object
              properties:
                field1:
                  type: string
                  pattern: '^[a-zA-Z0-9]+$'  # Validation rule
  scope: Namespaced
  names:
    plural: myresources
    singular: myresource
    kind: MyResource

What happens if the validation fails?

If the validation fails, Kubernetes will reject the request to create or update the custom resource, and you'll receive an error message indicating the validation issues.