[Bug] AWSManagedControlPlane deletion fails validation with BYO VPC

[MinhNguyen-at]

/kind bug

What steps did you take and what happened:

1. Create an AWSManagedControlPlane with a self-managed VPC and no addons mentioned in spec

spec:
  network:
    vpc:
      id: vpc-myidhere

2. Let provisioning complete
3. Delete AWSManagedControlPlane
4. Observe event
   E0909 22:20:45.932177 1 controller.go:316] "Reconciler error" err="failed to patch AWSManagedControlPlane cluster-namespace/cluster-name: admission webhook "validation.awsmanagedcontrolplanes.controlplane.cluster.x-k8s.io" denied the request: AWSManagedControlPlane.controlplane.cluster.x-k8s.io "cluster-name" is invalid: [spec.addons: Invalid value: "": addons are required to be set explicitly if IPv6 is enabled, spec.network.vpc.enableIPv6: Invalid value: true: changing IP family is not allowed after it has been set]" controller="awsmanagedcontrolplane" controllerGroup="controlplane.cluster.x-k8s.io" controllerKind="AWSManagedControlPlane" AWSManagedControlPlane="cluster-namespace/cluster-name" namespace="cluster-namespace" name="cluster-name" reconcileID="89c04084-8af5-44e3-803e-2ae00242b051"
5. edit validatingwebhookconfiguration for awsmanagedcontrolplane to not apply to UPDATE
6. observe deletion complete successfully

What did you expect to happen:
ValidatingWebhookConfiguration does not block a valid change made by the CAPA's inner workings.

Environment:

• Cluster-api-provider-aws version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

[k8s-ci-robot]

This issue is currently awaiting triage.

If CAPA/CAPI contributors determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.