crd status patch

scaler-cr.yaml

apiVersion: example.com/v1
kind: Scaler
metadata:
  name: foo
spec:
  replicas: 1

scaler-crd.yaml

apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  name: scalers.example.com
spec:
  group: example.com
  scope: Namespaced
  preserveUnknownFields: false
  versions:
  - name: v1
    storage: true
    served: true
    schema:
      openAPIV3Schema:
        type: object
        properties:
          spec:
            type: object
            properties:
              replicas:
                type: integer
          status:
            type: object
            properties:
              selector:
                type: string
              replicas:
                type: integer
    subresources:
      status: {}
      scale:
        statusReplicasPath: .status.replicas
        specReplicasPath: .spec.replicas
        labelSelectorPath: .status.selector
  names:
    singular: scaler
    plural: scalers
    kind: Scaler
    listKind: ScalerList

scaler.sh

$ kubectl create -f scaler-crd.yaml
customresourcedefinition.apiextensions.k8s.io/scalers.example.com created

$ kubectl create -f scaler-cr.yaml
scaler.example.com/foo created

$ curl -s -X PATCH \
  -H "Content-Type: application/merge-patch+json" \
  --data '{"status":{"selector":"foo"}}' \
  http://localhost:8080/apis/example.com/v1/namespaces/default/scalers/foo/status | jq .

{
  "apiVersion": "example.com/v1",
  "kind": "Scaler",
  "metadata": {
    "creationTimestamp": "2019-12-20T16:10:32Z",
    "generation": 1,
    "name": "foo",
    "namespace": "default",
    "resourceVersion": "302",
    "selfLink": "/apis/example.com/v1/namespaces/default/scalers/foo/status",
    "uid": "b9e2f122-ffd3-4d73-9d51-7932994f8b82"
  },
  "spec": {
    "replicas": 1
  },
  "status": {
    "selector": "foo"
  }
}