backport clusterctl discovery fix

This patch was originally introduced in PR #5684.
Original name: "clusterctl discovery should ignore provider's resources"
Original commit id: db5b183

Original description:

While managing components (for cert-manager or providers) clusterctl
implements a discovery function to seek for all the objects
part of the component.

This commit makes this code to ignore resources for a provider
(e.g Cluster for CAPI, AWSCluster for CAPA, Certificates for cert-manager)
given that those resources are not part of the component itself.

This will make operations like upgrade plan or apply and delete resilient to actual
state of cert-manager web hooks; in fact, those operations can now work when
web-hooks are not functioning (due to provider's deployment already deleted,
to provider scaled down to 0, to other errors)

Reason for backporting:

This issue that was solved in db5b183 on the main branch is also effecting
older releases of CAPI currently in use thus the patch is applicable
on older branches.

cmd/clusterctl/client/cluster/proxy.go

@@ -22,14 +22,18 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/util/sets"
 	utilversion "k8s.io/apimachinery/pkg/util/version"
 	"k8s.io/client-go/discovery"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
+	clusterv1 "sigs.k8s.io/cluster-api/api/v1alpha4"
+	clusterctlv1 "sigs.k8s.io/cluster-api/cmd/clusterctl/api/v1alpha3"
 	"sigs.k8s.io/cluster-api/cmd/clusterctl/internal/scheme"
 	"sigs.k8s.io/cluster-api/version"
 	"sigs.k8s.io/controller-runtime/pkg/client"
@@ -171,6 +175,30 @@ func (k *proxy) ListResources(labels map[string]string, namespaces ...string) ([
 		return nil, errors.Wrap(err, "failed to list api resources")
 	}
 
+	// Exclude from discovery the objects from the cert-manager/provider's CRDs.
+	// Those objects are not part of the components, and they will eventually be removed when removing the CRD definition.
+	crdsToExclude := sets.String{}
+
+	crdList := &apiextensionsv1.CustomResourceDefinitionList{}
+	if err := retryWithExponentialBackoff(newReadBackoff(), func() error {
+		return c.List(ctx, crdList)
+	}); err != nil {
+		return nil, errors.Wrap(err, "failed to list CRDs")
+	}
+	for _, crd := range crdList.Items {
+		component, isCoreComponent := labels[clusterctlv1.ClusterctlCoreLabelName]
+		_, isProviderResource := crd.Labels[clusterv1.ProviderLabelName]
+		if (isCoreComponent && component == clusterctlv1.ClusterctlCoreLabelCertManagerValue) || isProviderResource {
+			for _, version := range crd.Spec.Versions {
+				crdsToExclude.Insert(metav1.GroupVersionKind{
+					Group:   crd.Spec.Group,
+					Version: version.Name,
+					Kind:    crd.Spec.Names.Kind,
+				}.String())
+			}
+		}
+	}
+
 	// Select resources with list and delete methods (list is required by this method, delete by the callers of this method)
 	resourceList = discovery.FilteredBy(discovery.SupportsAllVerbs{Verbs: []string{"list", "delete"}}, resourceList)