metadata field not created after creation of resource

[akgowda]

I created a Deployment wrapper Controller. But the template's metadata field is empty even though I've added labels/annotations to the resource.

apiVersion: test.domain/v1
kind: DhruvaDeployment
metadata:
  name: dhruvadeployment-sample
spec:
  deploymentSpec:
    selector:
      matchLabels:
        foo: bar
    template:
      metadata:
        labels:
          foo: bar
        annotations:
          test1: testAnnot
      spec:
        containers:
          - name: app
            image: busybox
            args:
              - /bin/sh
              - -c
              - "date; echo Hello from the Kubernetes cluster; trap : TERM INT; sleep infinity & wait"

---

ubuntu@master-node:~$ kubectl  get dhruvadeployments.test.domain dhruvadeployment-sample -o yaml
apiVersion:test.domain/v1
kind: DhruvaDeployment
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"test.domain/v1","kind":"DhruvaDeployment","metadata":{"annotations":{},"name":"dhruvadeployment-sample","namespace":"default"},"spec":{"deploymentSpec":{"selector":{"matchLabels":{"foo":"bar"}},"template":{"metadata":{"annotations":{"test1":"testAnnot"},"labels":{"foo":"bar"}},"spec":{"containers":[{"args":["/bin/sh","-c","date; echo Hello from the Kubernetes cluster; trap : TERM INT; sleep infinity \u0026 wait"],"image":"busybox","name":"app"}]}}}}}
  creationTimestamp: "2022-06-14T10:37:34Z"
  generation: 2
  name: dhruvadeployment-sample
  namespace: default
  resourceVersion: "2426014"
  uid: 711a4a99-6537-4a18-9977-bc7d925dfa15
spec:
  deploymentSpec:
    selector:
      matchLabels:
        foo: bar
    template:
      metadata: {}
      spec:
        containers:
        - args:
          - /bin/sh
          - -c
          - 'date; echo Hello from the Kubernetes cluster; trap : TERM INT; sleep
            infinity & wait'
          image: busybox
          name: app

[akgowda]

I can see that kubectl.kubernetes.io/last-applied-configuration annotation has labels/annotations.

[akgowda]

The issue is with CRD generated by kubebuilder. x-kubernetes-preserve-unknown-fields: true is missing for metadata object. As per https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#field-pruning , we need to add this else labels or annotations added to metadata of any subresource will be pruned.

[camilamacedo86]

Hi @akgowda,

I think you've correctly diagnosed the issue. In Kubernetes, the Custom Resource Definitions (CRDs) have a feature called "field pruning". This feature ensures that unknown fields in the custom resource (CR) don't get saved to etcd. Given this, if you define fields in the CR that aren't present in the CRD, they will be pruned and won't be saved.

For your DhruvaDeployment, the metadata under the template spec is not being preserved, hence the missing labels and annotations.

To retain these fields, you can use the x-kubernetes-preserve-unknown-fields: true annotation for the specific field in the CRD. In this case, you'd want to apply it to the metadata field of the template to ensure the subfields (like labels and annotations) are preserved.

I understand that you could solve that by using the marker: // +kubebuilder:pruning:PreserveUnknownFields More info: https://book.kubebuilder.io/reference/markers/crd-processing

Since it seems that no longer need interactions I am closing this one but feel free to re-open if you need to do so,