use subpath for coredns only for default repository

cmd/kubeadm/app/constants/constants.go

@@ -326,7 +326,7 @@ const (
 	CoreDNSDeploymentName = "coredns"
 
 	// CoreDNSImageName specifies the name of the image for CoreDNS add-on
-	CoreDNSImageName = "coredns/coredns"
+	CoreDNSImageName = "coredns"
 
 	// CoreDNSVersion is the version of CoreDNS to be deployed if it is used
 	CoreDNSVersion = "v1.8.0"

cmd/kubeadm/app/images/images.go

@@ -21,6 +21,7 @@ import (
 
 	"k8s.io/klog/v2"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+	kubeadmapiv1beta2 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta2"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 )
@@ -46,6 +47,10 @@ func GetDNSImage(cfg *kubeadmapi.ClusterConfiguration) string {
 	if cfg.DNS.ImageRepository != "" {
 		dnsImageRepository = cfg.DNS.ImageRepository
 	}
+	// Handle the renaming of the official image from "k8s.gcr.io/coredns" to "k8s.gcr.io/coredns/coredns
+	if dnsImageRepository == kubeadmapiv1beta2.DefaultImageRepository {
+		dnsImageRepository = fmt.Sprintf("%s/coredns", dnsImageRepository)
+	}
 	// DNS uses an imageTag that corresponds to the DNS version matching the Kubernetes version
 	dnsImageTag := constants.GetDNSVersion(cfg.DNS.Type)
 

cmd/kubeadm/app/images/images_test.go

@@ -22,6 +22,7 @@ import (
 	"testing"
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+	kubeadmapiv1beta2 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1beta2"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 )
 
@@ -229,3 +230,52 @@ func TestGetAllImages(t *testing.T) {
 		})
 	}
 }
+
+func TestGetDNSImage(t *testing.T) {
+	var tests = []struct {
+		expected string
+		cfg      *kubeadmapi.ClusterConfiguration
+	}{
+		{
+			expected: "foo.io/coredns:v1.8.0",
+			cfg: &kubeadmapi.ClusterConfiguration{
+				ImageRepository: "foo.io",
+				DNS: kubeadmapi.DNS{
+					Type: kubeadmapi.CoreDNS,
+				},
+			},
+		},
+		{
+			expected: kubeadmapiv1beta2.DefaultImageRepository + "/coredns/coredns:v1.8.0",
+			cfg: &kubeadmapi.ClusterConfiguration{
+				ImageRepository: kubeadmapiv1beta2.DefaultImageRepository,
+				DNS: kubeadmapi.DNS{
+					Type: kubeadmapi.CoreDNS,
+				},
+			},
+		},
+		{
+			expected: "foo.io/coredns/coredns:v1.8.0",
+			cfg: &kubeadmapi.ClusterConfiguration{
+				ImageRepository: "foo.io",
+				DNS: kubeadmapi.DNS{
+					Type: kubeadmapi.CoreDNS,
+					ImageMeta: kubeadmapi.ImageMeta{
+						ImageRepository: "foo.io/coredns",
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		actual := GetDNSImage(test.cfg)
+		if actual != test.expected {
+			t.Errorf(
+				"failed to GetDNSImage:\n\texpected: %s\n\t actual: %s",
+				test.expected,
+				actual,
+			)
+		}
+	}
+}