controller-gen: k8s.io/api/core/v1.Container ports are broken for v1beta1 CRDs on k8s v1.18

[estroz]

From the original issue operator-framework/operator-sdk#3235:

An api/v1/types.go containing k8s.io/api/core/v1.Container:

// +kubebuilder:object:generate=true
// +groupName=example.com
package v1

import (
	"k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"sigs.k8s.io/controller-runtime/pkg/scheme"
)

var (
	GroupVersion  = schema.GroupVersion{Group: "example.com", Version: "v1"}
	SchemeBuilder = &scheme.Builder{GroupVersion: GroupVersion}
	AddToScheme   = SchemeBuilder.AddToScheme
)

type AppSpec struct {
	Containers v1.Container `json:"container"`
}

type AppStatus struct{}

// +kubebuilder:object:root=true
// +kubebuilder:subresource:status

type App struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`

	Spec   AppSpec   `json:"spec,omitempty"`
	Status AppStatus `json:"status,omitempty"`
}

Then:

$ go get sigs.k8s.io/controller-tools/cmd/controller-gen@master
go: found sigs.k8s.io/controller-tools/cmd/controller-gen in sigs.k8s.io/controller-tools v0.4.2-0.20201118235450-895eccc97eb5
$ controller-gen crd:crdVersions=v1beta1 paths=./api/v1/... output:crd:artifacts:config=.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
$ kind create cluster --image=kindest/node:v1.18.8 # Kubernetes v1.18 cluster
...
$ kubectl apply -f example.com_apps.yaml
The CustomResourceDefinition "apps.example.com" is invalid: spec.validation.openAPIV3Schema.properties[spec].properties[container].properties[ports].items.properties[protocol].default: Required value: this property is in x-kubernetes-list-map-keys, so it must have a default or be a required property

Removing protocol from the x-kubernetes-list-map-keys list fixes this (as expected) since defaulting is not supported in v1beta1. This was fixed for v1 CRDs but the fixes (listed below) were not tested on v1beta1 CRDs afaict.

Related issues: #444, #445, kubernetes/kubernetes#91395

/kind bug

/cc @munnerz @vincepri

[johscheuer]

I got a slightly different error:

Type: "FieldValueForbidden",
Message: "Forbidden: must not be set",
Field: "spec.validation.openAPIV3Schema.properties[spec].properties[processes].additionalProperties.properties[podTemplate].properties[spec].properties[containers].items.properties[ports].items.properties[protocol].default",

and during the generation I can see the following warnings:

Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.
Warning: default unsupported in CRD version v1beta1, v1 required. Removing defaults.

So I suspect that not all defaults are catched during the generation.

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