Use metadata.Client instead of resource.Builder

This is more efficient. It only fetches the metadata, not the actual
resources. It also behaves like a classic Kubernetes client and
doesn't require a RESTClientGetter. Since this is the last use of k0s'
RESTClientGetter implementation, this file could be dropped entirely.

Signed-off-by: Tom Wieczorek <twieczorek@mirantis.com>

pkg/autopilot/checks/checks.go

@@ -15,19 +15,22 @@
 package checks
 
 import (
+	"context"
 	"fmt"
 
+	"github.com/k0sproject/k0s/pkg/kubernetes"
+	"github.com/k0sproject/k0s/static"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/metadata"
+
 	"github.com/sirupsen/logrus"
 	"golang.org/x/mod/semver"
-	"k8s.io/apimachinery/pkg/runtime/schema"
-	"k8s.io/cli-runtime/pkg/resource"
 	"sigs.k8s.io/yaml"
-
-	"github.com/k0sproject/k0s/pkg/kubernetes"
-	"github.com/k0sproject/k0s/static"
 )
 
-func CanUpdate(log logrus.FieldLogger, clientFactory kubernetes.ClientFactoryInterface, newVersion string) error {
+func CanUpdate(ctx context.Context, log logrus.FieldLogger, clientFactory kubernetes.ClientFactoryInterface, newVersion string) error {
 	removedAPIs, err := GetRemovedAPIsList()
 	if err != nil {
 		return err
@@ -46,13 +49,10 @@ func CanUpdate(log logrus.FieldLogger, clientFactory kubernetes.ClientFactoryInt
 		}
 	}
 
-	restClientGetter := kubernetes.NewRESTClientGetter(clientFactory, log)
-	resourceBuilder := resource.NewBuilder(restClientGetter).
-		Unstructured().
-		ContinueOnError().
-		Flatten().
-		AllNamespaces(true).
-		Latest()
+	metaClient, err := metadata.NewForConfig(clientFactory.GetRESTConfig())
+	if err != nil {
+		return err
+	}
 
 	for _, r := range resources {
 		gv, err := schema.ParseGroupVersion(r.GroupVersion)
@@ -71,26 +71,19 @@ func CanUpdate(log logrus.FieldLogger, clientFactory kubernetes.ClientFactoryInt
 				gv.Version = ar.Version
 			}
 
-			gvk := gv.WithKind(ar.Kind)
-
-			removedInVersion, ok := removedAPIs[gvk]
+			removedInVersion, ok := removedAPIs[gv.WithKind(ar.Kind)]
 			if !ok || semver.Compare(newVersion, removedInVersion) < 0 {
 				continue
 			}
 
-			res := resourceBuilder.ResourceTypeOrNameArgs(true, ar.Kind).Do()
-			infos, err := res.Infos()
+			metas, err := metaClient.Resource(gv.WithResource(ar.Name)).
+				Namespace(metav1.NamespaceAll).
+				List(ctx, metav1.ListOptions{})
 			if err != nil {
 				return err
 			}
 
-			found := 0
-			for _, i := range infos {
-				if gvk == i.Mapping.GroupVersionKind {
-					found++
-				}
-			}
-			if found > 0 {
+			if found := len(metas.Items); found > 0 {
 				return fmt.Errorf("%s.%s %s has been removed in Kubernetes %s, but there are %d such resources in the cluster", ar.Name, gv.Group, gv.Version, removedInVersion, found)
 			}
 		}

pkg/autopilot/controller/plans/cmdprovider/airgapupdate/newplan.go

@@ -27,7 +27,7 @@ func (aup *airgapupdate) NewPlan(ctx context.Context, cmd apv1beta2.PlanCommand,
 	logger := aup.logger.WithField("state", "newplan")
 	logger.Info("Processing")
 
-	if err := checks.CanUpdate(logger, aup.cf, cmd.AirgapUpdate.Version); err != nil {
+	if err := checks.CanUpdate(ctx, logger, aup.cf, cmd.AirgapUpdate.Version); err != nil {
 		status.State = appc.PlanWarning
 		status.Description = err.Error()
 		return appc.PlanWarning, false, err

pkg/autopilot/controller/plans/cmdprovider/k0supdate/newplan.go

@@ -34,7 +34,7 @@ func (kp *k0supdate) NewPlan(ctx context.Context, cmd apv1beta2.PlanCommand, sta
 	logger.Info("Processing")
 
 	if !cmd.K0sUpdate.ForceUpdate {
-		if err := checks.CanUpdate(logger, kp.cf, cmd.K0sUpdate.Version); err != nil {
+		if err := checks.CanUpdate(ctx, logger, kp.cf, cmd.K0sUpdate.Version); err != nil {
 			status.State = appc.PlanWarning
 			status.Description = err.Error()
 			return appc.PlanWarning, false, err