simplify code by switching from docker lib to util pkg

- use func in util pkg instead of exteral docker reference library to simplify the code

cmd/clusterctl/client/config/imagemeta_client.go

@@ -17,11 +17,10 @@ limitations under the License.
 package config
 
 import (
-	"fmt"
 	"strings"
 
-	"github.com/docker/distribution/reference"
 	"github.com/pkg/errors"
+	"sigs.k8s.io/cluster-api/util/container"
 )
 
 const (
@@ -119,53 +118,20 @@ func (i *imageMeta) Union(other *imageMeta) {
 
 // ApplyToImage changes an image name applying the transformations defined in the current imageMeta.
 func (i *imageMeta) ApplyToImage(image string) (string, error) {
-	// Splits the image name into its own composing parts
-	ref, err := reference.ParseNormalizedNamed(image)
+
+	newImage, err := container.ImageFromString(image)
 	if err != nil {
 		return "", err
 	}
 
 	// apply transformations
 	if i.Repository != "" {
-		// store tag & digest for rebuilding the image name
-		tagged, hasTag := ref.(reference.Tagged)
-		digested, hasDigest := ref.(reference.Digested)
-
-		// detect the image name, dropping host and path if any
-		name := ref.Name()
-		imageNameIndex := strings.LastIndex(name, "/")
-		if imageNameIndex != -1 {
-			name = strings.TrimPrefix(name[imageNameIndex+1:], "/")
-		}
-
-		// parse the new image resulting by concatenating the new repository and the image name
-		ref, err = reference.ParseNormalizedNamed(fmt.Sprintf("%s/%s", strings.TrimSuffix(i.Repository, "/"), name))
-		if err != nil {
-			return "", err
-		}
-
-		// applies back tag & digest
-		if hasTag {
-			ref, err = reference.WithTag(ref, tagged.Tag())
-			if err != nil {
-				return "", err
-			}
-		}
-
-		if hasDigest {
-			ref, err = reference.WithDigest(ref, digested.Digest())
-			if err != nil {
-				return "", err
-			}
-		}
+		newImage.Repository = strings.TrimSuffix(i.Repository, "/")
 	}
 	if i.Tag != "" {
-		ref, err = reference.WithTag(reference.TrimNamed(ref), i.Tag)
-		if err != nil {
-			return "", err
-		}
+		newImage.Tag = i.Tag
 	}
 
 	// returns the resulting image name
-	return ref.String(), nil
+	return newImage.String(), nil
 }

controlplane/kubeadm/internal/workload_cluster_coredns.go

@@ -21,7 +21,6 @@ import (
 	"fmt"
 
 	"github.com/coredns/corefile-migration/migration"
-	"github.com/docker/distribution/reference"
 	"github.com/pkg/errors"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
@@ -30,6 +29,7 @@ import (
 	kubeadmv1 "sigs.k8s.io/cluster-api/bootstrap/kubeadm/types/v1beta1"
 	controlplanev1 "sigs.k8s.io/cluster-api/controlplane/kubeadm/api/v1alpha3"
 	"sigs.k8s.io/cluster-api/util"
+	containerutil "sigs.k8s.io/cluster-api/util/container"
 	"sigs.k8s.io/cluster-api/util/patch"
 	ctrlclient "sigs.k8s.io/controller-runtime/pkg/client"
 )
@@ -143,13 +143,13 @@ func (w *Workload) getCoreDNSInfo(ctx context.Context, clusterConfig *kubeadmv1.
 	}
 
 	// Parse container image.
-	parsedImage, err := reference.ParseNormalizedNamed(container.Image)
+	parsedImage, err := containerutil.ImageFromString(container.Image)
 	if err != nil {
 		return nil, errors.Wrapf(err, "unable to parse %q deployment image", container.Image)
 	}
 
 	// Handle imageRepository.
-	toImageRepository := fmt.Sprintf("%s/%s", reference.Domain(parsedImage), reference.Path(parsedImage))
+	toImageRepository := fmt.Sprintf("%s/%s", parsedImage.Repository, parsedImage.Name)
 	if clusterConfig.ImageRepository != "" {
 		toImageRepository = fmt.Sprintf("%s/%s", clusterConfig.ImageRepository, coreDNSKey)
 	}
@@ -158,15 +158,14 @@ func (w *Workload) getCoreDNSInfo(ctx context.Context, clusterConfig *kubeadmv1.
 	}
 
 	// Handle imageTag.
-	imageRefTag, ok := parsedImage.(reference.Tagged)
-	if !ok {
+	if parsedImage.Tag == "" {
 		return nil, errors.Errorf("failed to update coredns deployment: does not have a valid image tag: %q", container.Image)
 	}
-	currentMajorMinorPatch, err := extractImageVersion(imageRefTag.Tag())
+	currentMajorMinorPatch, err := extractImageVersion(parsedImage.Tag)
 	if err != nil {
 		return nil, err
 	}
-	toImageTag := imageRefTag.Tag()
+	toImageTag := parsedImage.Tag
 	if clusterConfig.DNS.ImageTag != "" {
 		toImageTag = clusterConfig.DNS.ImageTag
 	}
@@ -180,7 +179,7 @@ func (w *Workload) getCoreDNSInfo(ctx context.Context, clusterConfig *kubeadmv1.
 		Deployment:             deployment,
 		CurrentMajorMinorPatch: currentMajorMinorPatch,
 		TargetMajorMinorPatch:  targetMajorMinorPatch,
-		FromImageTag:           imageRefTag.Tag(),
+		FromImageTag:           parsedImage.Tag,
 		ToImageTag:             toImageTag,
 		FromImage:              container.Image,
 		ToImage:                fmt.Sprintf("%s:%s", toImageRepository, toImageTag),