kubernetes custom resource definition required field

If you are on v1.8, you will need to enable the CustomResourceValidation feature gate for using the validation feature. This can be done by using the following flag on kube-apiserver:

--feature-gates=CustomResourceValidation=true

Here is an example of it working (I tested this on v1.12, but this should work on earlier versions as well):

The CRD:

apiVersion: apiextensions.k8s.io/v1beta1kind: CustomResourceDefinitionmetadata:  name: foos.stable.example.comspec:  group: stable.example.com  versions:    - name: v1      served: true      storage: true  version: v1  scope: Namespaced  names:    plural: foos    singular: foo    kind: Foo  validation:    openAPIV3Schema:      properties:        spec:          properties:            vc:              type: array              items:                type: object                properties:                  name:                    type: string                  address:                    type: string                required:                - name

The custom resource:

apiVersion: "stable.example.com/v1"kind: Foometadata:  name: new-foospec:  vc:  - address: "bar"

1. Create the CRD.

kubectl create -f crd.yamlcustomresourcedefinition.apiextensions.k8s.io/foos.stable.example.com created

2. Get the CRD and check if the validation field exists in the output. If it doesn't, you probably don't have the feature gate turned on.

kubectl get crd foos.stable.example.com -oyaml

3. Try to create the custom resource. This should fail with:

kubectl create -f cr-validation.yaml

The Foo "new-foo" is invalid: []: Invalid value: map[string]interface {}{"metadata":map[string]interface {}{"creationTimestamp":"2018-11-18T19:45:23Z", "generation":1, "uid":"7d7f8f0b-eb6a-11e8-b861-54e1ad9de0be", "name":"new-foo", "namespace":"default"}, "spec":map[string]interface {}{"vc":[]interface {}{map[string]interface {}{"address":"bar"}}}, "apiVersion":"stable.example.com/v1", "kind":"Foo"}: validation failure list:spec.vc.name in body is required