stop gap for kubeadm types removal

bootstrap/kubeadm/controllers/kubeadmconfig_controller.go

@@ -379,7 +379,7 @@ func (r *KubeadmConfigReconciler) handleClusterNotInitialized(ctx context.Contex
 			},
 		}
 	}
-	initdata, err := kubeadmv1beta1.ConfigurationToYAML(scope.Config.Spec.InitConfiguration)
+	initdata, err := kubeadmv1beta1.ConfigurationToYAMLForVersion(scope.Config.Spec.InitConfiguration, scope.ConfigOwner.KubernetesVersion())
 	if err != nil {
 		scope.Error(err, "Failed to marshal init configuration")
 		return ctrl.Result{}, err
@@ -397,7 +397,7 @@ func (r *KubeadmConfigReconciler) handleClusterNotInitialized(ctx context.Contex
 	// injects into config.ClusterConfiguration values from top level object
 	r.reconcileTopLevelObjectSettings(scope.Cluster, machine, scope.Config)
 
-	clusterdata, err := kubeadmv1beta1.ConfigurationToYAML(scope.Config.Spec.ClusterConfiguration)
+	clusterdata, err := kubeadmv1beta1.ConfigurationToYAMLForVersion(scope.Config.Spec.ClusterConfiguration, scope.ConfigOwner.KubernetesVersion())
 	if err != nil {
 		scope.Error(err, "Failed to marshal cluster configuration")
 		return ctrl.Result{}, err
@@ -479,7 +479,7 @@ func (r *KubeadmConfigReconciler) joinWorker(ctx context.Context, scope *Scope)
 		return res, nil
 	}
 
-	joinData, err := kubeadmv1beta1.ConfigurationToYAML(scope.Config.Spec.JoinConfiguration)
+	joinData, err := kubeadmv1beta1.ConfigurationToYAMLForVersion(scope.Config.Spec.JoinConfiguration, scope.ConfigOwner.KubernetesVersion())
 	if err != nil {
 		scope.Error(err, "Failed to marshal join configuration")
 		return ctrl.Result{}, err
@@ -560,7 +560,7 @@ func (r *KubeadmConfigReconciler) joinControlplane(ctx context.Context, scope *S
 		return res, nil
 	}
 
-	joinData, err := kubeadmv1beta1.ConfigurationToYAML(scope.Config.Spec.JoinConfiguration)
+	joinData, err := kubeadmv1beta1.ConfigurationToYAMLForVersion(scope.Config.Spec.JoinConfiguration, scope.ConfigOwner.KubernetesVersion())
 	if err != nil {
 		scope.Error(err, "Failed to marshal join configuration")
 		return ctrl.Result{}, err

bootstrap/kubeadm/controllers/kubeadmconfig_controller_test.go

@@ -1813,6 +1813,7 @@ func newMachine(cluster *clusterv1.Cluster, name string) *clusterv1.Machine {
 					APIVersion: bootstrapv1.GroupVersion.String(),
 				},
 			},
+			Version: pointer.StringPtr("v1.19.1"),
 		},
 	}
 	if cluster != nil {
@@ -1854,6 +1855,7 @@ func newMachinePool(cluster *clusterv1.Cluster, name string) *expv1.MachinePool
 							APIVersion: bootstrapv1.GroupVersion.String(),
 						},
 					},
+					Version: pointer.StringPtr("v1.19.1"),
 				},
 			},
 		},

bootstrap/kubeadm/types/v1beta1/utils.go

@@ -17,12 +17,72 @@ limitations under the License.
 package v1beta1
 
 import (
+	"strings"
+
 	"github.com/pkg/errors"
 	runtime "k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	versionutil "k8s.io/apimachinery/pkg/util/version"
+	"sigs.k8s.io/cluster-api/bootstrap/kubeadm/types/v1beta2"
 	"sigs.k8s.io/controller-runtime/pkg/scheme"
 )
 
+func KubeVersionToKubeadmAPIGroupVersion(version string) (schema.GroupVersion, error) {
+	if version == "" {
+		return schema.GroupVersion{}, errors.New("version cannot be empty")
+	}
+	semVersion, err := versionutil.ParseSemantic(version)
+	if err != nil {
+		return schema.GroupVersion{}, errors.Wrap(err, "error parsing the Kubernetes version")
+	}
+	switch {
+	case semVersion.LessThan(versionutil.MustParseSemantic("v1.13.0")):
+		return schema.GroupVersion{}, errors.New("the bootstrap provider for kubeadm doesn't support Kubernetes version lower than v1.13.0")
+	case semVersion.LessThan(versionutil.MustParseSemantic("v1.15.0")):
+		// NOTE: All the Kubernetes version >= v1.13 and < v1.15 should use the kubeadm API version v1beta1
+		return GroupVersion, nil
+	default:
+		// NOTE: All the Kubernetes version greater or equal to v1.15  should use the kubeadm API version v1beta2.
+		// Also future Kubernetes versions (not yet released at the time of writing this code) are going to use v1beta2,
+		// no matter if kubeadm API versions newer than v1beta2 could be introduced by those release.
+		// This is acceptable because but v1beta2 will be supported by kubeadm until the deprecation cycle completes
+		// (9 months minimum after the deprecation date, not yet announced now); this gives Cluster API project time to
+		// introduce support for newer releases without blocking users to deploy newer version of Kubernetes.
+		return v1beta2.GroupVersion, nil
+	}
+}
+
+// ConfigurationToYAMLForVersion converts a kubeadm configuration type to its YAML
+// representation.
+func ConfigurationToYAMLForVersion(obj runtime.Object, k8sVersion string) (string, error) {
+	yamlBytes, err := MarshalToYamlForCodecs(obj, GroupVersion, GetCodecs())
+	if err != nil {
+		return "", errors.Wrap(err, "failed to marshal configuration")
+	}
+
+	yaml := string(yamlBytes)
+
+	// Fix the YAML according to the target Kubernetes version
+	// IMPORTANT: This is a stop-gap explicitly designed for back-porting on the v1alpha3 branch.
+	// This allows to unblock removal of the v1beta1 API in kubeadm by making Cluster API to use the v1beta2 kubeadm API
+	// under the assumption that the serialized version of the two APIs is equal as discussed; see
+	// "Insulate users from kubeadm API version changes" CAEP for more details.
+	// NOTE: This solution will stop to work when kubeadm will drop then v1beta2 kubeadm API, but this gives
+	// enough time (9/12 months from the deprecation date, not yet announced) for the users to migrate to
+	// the v1alpha4 release of Cluster API, where a proper conversion mechanism is going to be supported.
+	gv, err := KubeVersionToKubeadmAPIGroupVersion(k8sVersion)
+	if err != nil {
+		return "", err
+	}
+
+	if gv != GroupVersion {
+		yaml = strings.Replace(yaml, GroupVersion.String(), gv.String(), -1)
+	}
+
+	return yaml, nil
+}
+
 // GetCodecs returns a type that can be used to deserialize most kubeadm
 // configuration types.
 func GetCodecs() serializer.CodecFactory {

bootstrap/kubeadm/types/v1beta1/utils_test.go

@@ -0,0 +1,160 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1beta1
+
+import (
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	. "github.com/onsi/gomega"
+
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/cluster-api/bootstrap/kubeadm/types/v1beta2"
+)
+
+func Test_KubeVersionToKubeadmAPIGroupVersion(t *testing.T) {
+	type args struct {
+		k8sVersion string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    schema.GroupVersion
+		wantErr bool
+	}{
+		{
+			name: "fails when kubernetes version is too old",
+			args: args{
+				k8sVersion: "v1.12.0",
+			},
+			want:    schema.GroupVersion{},
+			wantErr: true,
+		},
+		{
+			name: "pass with minimum kubernetes version for kubeadm API v1beta1",
+			args: args{
+				k8sVersion: "v1.13.0",
+			},
+			want:    GroupVersion,
+			wantErr: false,
+		},
+		{
+			name: "pass with kubernetes version for kubeadm API v1beta1",
+			args: args{
+				k8sVersion: "v1.14.99",
+			},
+			want:    GroupVersion,
+			wantErr: false,
+		},
+		{
+			name: "pass with minimum kubernetes version for kubeadm API v1beta2",
+			args: args{
+				k8sVersion: "v1.15.0",
+			},
+			want:    v1beta2.GroupVersion,
+			wantErr: false,
+		},
+		{
+			name: "pass with kubernetes version for kubeadm API v1beta2",
+			args: args{
+				k8sVersion: "v1.20.99",
+			},
+			want:    v1beta2.GroupVersion,
+			wantErr: false,
+		},
+		{
+			name: "pass with future kubernetes version",
+			args: args{
+				k8sVersion: "v99.99.99",
+			},
+			want:    v1beta2.GroupVersion,
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			got, err := KubeVersionToKubeadmAPIGroupVersion(tt.args.k8sVersion)
+			if tt.wantErr {
+				g.Expect(err).To(HaveOccurred())
+				return
+			}
+			g.Expect(err).ToNot(HaveOccurred())
+			g.Expect(got).To(Equal(tt.want))
+		})
+	}
+}
+
+func TestConfigurationToYAMLForVersion(t *testing.T) {
+	type args struct {
+		obj        *ClusterConfiguration
+		k8sVersion string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "Generates a v1beta1 kubeadm configuration with Kubernetes versions < 1.15",
+			args: args{
+				obj:        &ClusterConfiguration{},
+				k8sVersion: "v1.14.9",
+			},
+			want: "apiServer: {}\n" +
+				"apiVersion: kubeadm.k8s.io/v1beta1\n" + "" +
+				"controllerManager: {}\n" +
+				"dns: {}\n" +
+				"etcd: {}\n" +
+				"kind: ClusterConfiguration\n" +
+				"networking: {}\n" +
+				"scheduler: {}\n",
+			wantErr: false,
+		},
+		{
+			name: "Generates a v1beta2 kubeadm configuration with Kubernetes versions >= 1.15",
+			args: args{
+				obj:        &ClusterConfiguration{},
+				k8sVersion: "v1.15.0",
+			},
+			want: "apiServer: {}\n" +
+				"apiVersion: kubeadm.k8s.io/v1beta2\n" + "" +
+				"controllerManager: {}\n" +
+				"dns: {}\n" +
+				"etcd: {}\n" +
+				"kind: ClusterConfiguration\n" +
+				"networking: {}\n" +
+				"scheduler: {}\n",
+			wantErr: false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			g := NewWithT(t)
+
+			got, err := ConfigurationToYAMLForVersion(tt.args.obj, tt.args.k8sVersion)
+			if tt.wantErr {
+				g.Expect(err).To(HaveOccurred())
+				return
+			}
+			g.Expect(err).ToNot(HaveOccurred())
+			g.Expect(got).To(Equal(tt.want), cmp.Diff(tt.want, got))
+		})
+	}
+}

bootstrap/kubeadm/types/v1beta2/groupversion_info.go

@@ -0,0 +1,26 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package v1beta2
+
+import (
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+var (
+	// GroupVersion is group version used to register these objects
+	GroupVersion = schema.GroupVersion{Group: "kubeadm.k8s.io", Version: "v1beta2"}
+)

bootstrap/util/configowner.go

@@ -81,6 +81,20 @@ func (co ConfigOwner) IsMachinePool() bool {
 	return co.GetKind() == "MachinePool"
 }
 
+// Returns the Kuberentes version for the config owner object
+func (co ConfigOwner) KubernetesVersion() string {
+	fields := []string{"spec", "version"}
+	if co.IsMachinePool() {
+		fields = []string{"spec", "template", "spec", "version"}
+	}
+
+	version, _, err := unstructured.NestedString(co.Object, fields...)
+	if err != nil {
+		return ""
+	}
+	return version
+}
+
 // GetConfigOwner returns the Unstructured object owning the current resource.
 func GetConfigOwner(ctx context.Context, c client.Client, obj metav1.Object) (*ConfigOwner, error) {
 	allowedGKs := []schema.GroupKind{

bootstrap/util/configowner_test.go

@@ -54,6 +54,7 @@ func TestGetConfigOwner(t *testing.T) {
 				Bootstrap: clusterv1.Bootstrap{
 					DataSecretName: pointer.StringPtr("my-data-secret"),
 				},
+				Version: pointer.StringPtr("v1.19.6"),
 			},
 			Status: clusterv1.MachineStatus{
 				InfrastructureReady: true,
@@ -80,6 +81,8 @@ func TestGetConfigOwner(t *testing.T) {
 		g.Expect(configOwner.ClusterName()).To(BeEquivalentTo("my-cluster"))
 		g.Expect(configOwner.IsInfrastructureReady()).To(BeTrue())
 		g.Expect(configOwner.IsControlPlaneMachine()).To(BeTrue())
+		g.Expect(configOwner.IsMachinePool()).To(BeFalse())
+		g.Expect(configOwner.KubernetesVersion()).To(Equal("v1.19.6"))
 		g.Expect(*configOwner.DataSecretName()).To(BeEquivalentTo("my-data-secret"))
 	})
 
@@ -97,6 +100,11 @@ func TestGetConfigOwner(t *testing.T) {
 			},
 			Spec: expv1.MachinePoolSpec{
 				ClusterName: "my-cluster",
+				Template: clusterv1.MachineTemplateSpec{
+					Spec: clusterv1.MachineSpec{
+						Version: pointer.StringPtr("v1.19.6"),
+					},
+				},
 			},
 			Status: expv1.MachinePoolStatus{
 				InfrastructureReady: true,
@@ -123,6 +131,8 @@ func TestGetConfigOwner(t *testing.T) {
 		g.Expect(configOwner.ClusterName()).To(BeEquivalentTo("my-cluster"))
 		g.Expect(configOwner.IsInfrastructureReady()).To(BeTrue())
 		g.Expect(configOwner.IsControlPlaneMachine()).To(BeFalse())
+		g.Expect(configOwner.IsMachinePool()).To(BeTrue())
+		g.Expect(configOwner.KubernetesVersion()).To(Equal("v1.19.6"))
 		g.Expect(configOwner.DataSecretName()).To(BeNil())
 	})