Use CRD defaults

Problem

OADP does not use default value markers for generating its CRDs

// +kubebuilder:default=<value>

The adoption of this would be better for:

• developers

  Less code to write. Functions like this would not be necessary, as API would ensure a value is present on the field

  https://github.com/openshift/oadp-operator/blob/fb2411e2948874a6abe61ca31b1cd9957621ebb6/api/v1alpha1/oadp_types.go#L614-L617

• users

  Default values would be more visible to users. Easier to see when default values are updated

Examples

If user creates a DPA with this spec

spec:
  configuration:
    velero:
      logLevel: debug

it would have this spec in the cluster

spec:
  configuration:
    velero:
      client-burst: 100
      client-qps: 100
      defaultItemOperationTimeout: 1h
      disableInformerCache: false
      itemOperationSyncFrequency: 2m
      logLevel: debug
      noDefaultBackupLocation: false
      resourceTimeout: 10m

Note: default disallows user to remove field from object. If user try to remove a field with default from spec, API just adds it back with the default value.

Upgrades would work with these changes. A sample DPA prior to upgrade

apiVersion: oadp.openshift.io/v1alpha1
kind: DataProtectionApplication
metadata:
  creationTimestamp: '2024-10-14T14:47:20Z'
  generation: 3
  managedFields:
    ...
  name: velero-sample
  namespace: test-oadp-operator
  resourceVersion: '566563332'
  uid: 9f8ff5f5-041b-40bd-ba2e-6f7e658c7515
spec:
  backupImages: false
  configuration:
    velero:
      logLevel: debug
      noDefaultBackupLocation: true

The same DPA after upgarde

apiVersion: oadp.openshift.io/v1alpha1
kind: DataProtectionApplication
metadata:
  creationTimestamp: '2024-10-14T14:47:20Z'
  generation: 3
  managedFields:
    ...
  name: velero-sample
  namespace: test-oadp-operator
  resourceVersion: '566563332'
  uid: 9f8ff5f5-041b-40bd-ba2e-6f7e658c7515
spec:
  backupImages: false
  configuration:
    velero:
      client-burst: 100
      client-qps: 100
      defaultItemOperationTimeout: 1h
      disableInformerCache: false
      itemOperationSyncFrequency: 2m
      logLevel: debug
      noDefaultBackupLocation: true
      resourceTimeout: 10m

Note: even though the object changed, note that metadata.generation is the same on both objects.

References

https://book.kubebuilder.io/reference/markers/crd-validation
https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#defaulting

Note: some default values are not static, so they may be added with other strategies.

Start in api/v1alpha1/oadp_types.go around lines 614-617, then review the Kubebuilder CRD validation marker reference linked in the issue. Identify the static defaults represented by helper functions and determine how they should appear in generated CRDs. Done means applicable defaults are visible and applied to existing and newly created DataProtectionApplications, while non-static defaults use another strategy.