Fix v1alpha4 <-> v1beta1 conversions

v1alpha4 <-> v1beta1 conversions were failing and never tested.

As part of the PR
- Add a missing gcpclustertemplate_conversion.go file
- Add conversion test to make sure conversions work
- Add ObjectMeta to GCPClusterTemplateResource and GCPMachineTemplateResource.
  See kubernetes-sigs/cluster-api#5240

api/v1alpha3/gcpmachinetemplate_conversion.go

@@ -17,6 +17,7 @@ limitations under the License.
 package v1alpha3
 
 import (
+	apiconversion "k8s.io/apimachinery/pkg/conversion"
 	utilconversion "sigs.k8s.io/cluster-api/util/conversion"
 	"sigs.k8s.io/controller-runtime/pkg/conversion"
 
@@ -60,3 +61,8 @@ func (dst *GCPMachineTemplateList) ConvertFrom(srcRaw conversion.Hub) error { //
 	src := srcRaw.(*infrav1beta1.GCPMachineTemplateList)
 	return Convert_v1beta1_GCPMachineTemplateList_To_v1alpha3_GCPMachineTemplateList(src, dst, nil)
 }
+
+func Convert_v1beta1_GCPMachineTemplateResource_To_v1alpha3_GCPMachineTemplateResource(in *infrav1beta1.GCPMachineTemplateResource, out *GCPMachineTemplateResource, s apiconversion.Scope) error {
+	// NOTE: custom conversion func is required because spec.template.metadata has been added in v1beta1.
+	return autoConvert_v1beta1_GCPMachineTemplateResource_To_v1alpha3_GCPMachineTemplateResource(in, out, s)
+}

api/v1alpha4/conversion_test.go

@@ -0,0 +1,46 @@
+/*
+Copyright 2022 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 v1alpha4
+
+import (
+	"testing"
+
+	"sigs.k8s.io/cluster-api-provider-gcp/api/v1beta1"
+	utilconversion "sigs.k8s.io/cluster-api/util/conversion"
+)
+
+func TestFuzzyConversion(t *testing.T) {
+	t.Run("for GCPCluster", utilconversion.FuzzTestFunc(utilconversion.FuzzTestFuncInput{
+		Hub:    &v1beta1.GCPCluster{},
+		Spoke:  &GCPCluster{},
+	}))
+
+	t.Run("for GCPClusterTemplate", utilconversion.FuzzTestFunc(utilconversion.FuzzTestFuncInput{
+		Hub:    &v1beta1.GCPClusterTemplate{},
+		Spoke:  &GCPClusterTemplate{},
+	}))
+
+	t.Run("for GCPMachine", utilconversion.FuzzTestFunc(utilconversion.FuzzTestFuncInput{
+		Hub:    &v1beta1.GCPMachine{},
+		Spoke:  &GCPMachine{},
+	}))
+
+	t.Run("for GCPMachineTemplate", utilconversion.FuzzTestFunc(utilconversion.FuzzTestFuncInput{
+		Hub:    &v1beta1.GCPMachineTemplate{},
+		Spoke:  &GCPMachineTemplate{},
+	}))
+}

api/v1alpha4/gcpclustertemplate_conversion.go

@@ -0,0 +1,75 @@
+/*
+Copyright 2022 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 v1alpha4
+
+import (
+	apiconversion "k8s.io/apimachinery/pkg/conversion"
+	infrav1beta1 "sigs.k8s.io/cluster-api-provider-gcp/api/v1beta1"
+	utilconversion "sigs.k8s.io/cluster-api/util/conversion"
+	"sigs.k8s.io/controller-runtime/pkg/conversion"
+)
+
+// ConvertTo converts this GCPClusterTemplate to the Hub version (v1beta1).
+func (src *GCPClusterTemplate) ConvertTo(dstRaw conversion.Hub) error { // nolint
+	dst := dstRaw.(*infrav1beta1.GCPClusterTemplate)
+
+	if err := Convert_v1alpha4_GCPClusterTemplate_To_v1beta1_GCPClusterTemplate(src, dst, nil); err != nil {
+		return err
+	}
+
+	// Manually restore data.
+	restored := &infrav1beta1.GCPClusterTemplate{}
+	if ok, err := utilconversion.UnmarshalData(src, restored); err != nil || !ok {
+		return err
+	}
+
+	dst.Spec.Template.ObjectMeta = restored.Spec.Template.ObjectMeta
+
+	return nil
+}
+
+// ConvertFrom converts from the Hub version (v1beta1) to this version.
+func (dst *GCPClusterTemplate) ConvertFrom(srcRaw conversion.Hub) error { // nolint
+	src := srcRaw.(*infrav1beta1.GCPClusterTemplate)
+	if err := Convert_v1beta1_GCPClusterTemplate_To_v1alpha4_GCPClusterTemplate(src, dst, nil); err != nil {
+		return err
+	}
+
+	// Preserve Hub data on down-conversion.
+	if err := utilconversion.MarshalData(src, dst); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// ConvertTo converts this GCPClusterTemplateList to the Hub version (v1beta1).
+func (src *GCPClusterTemplateList) ConvertTo(dstRaw conversion.Hub) error { // nolint
+	dst := dstRaw.(*infrav1beta1.GCPClusterTemplateList)
+	return Convert_v1alpha4_GCPClusterTemplateList_To_v1beta1_GCPClusterTemplateList(src, dst, nil)
+}
+
+// ConvertFrom converts from the Hub version (v1beta1) to this version.
+func (dst *GCPClusterTemplateList) ConvertFrom(srcRaw conversion.Hub) error { // nolint
+	src := srcRaw.(*infrav1beta1.GCPClusterTemplateList)
+	return Convert_v1beta1_GCPClusterTemplateList_To_v1alpha4_GCPClusterTemplateList(src, dst, nil)
+}
+
+func Convert_v1beta1_GCPClusterTemplateResource_To_v1alpha4_GCPClusterTemplateResource(in *infrav1beta1.GCPClusterTemplateResource, out *GCPClusterTemplateResource, s apiconversion.Scope) error {
+	// NOTE: custom conversion func is required because spec.template.metadata has been added in v1beta1.
+	return autoConvert_v1beta1_GCPClusterTemplateResource_To_v1alpha4_GCPClusterTemplateResource(in, out, s)
+}

api/v1alpha4/gcpmachinetemplate_conversion.go

@@ -17,6 +17,7 @@ limitations under the License.
 package v1alpha4
 
 import (
+	apiconversion "k8s.io/apimachinery/pkg/conversion"
 	infrav1beta1 "sigs.k8s.io/cluster-api-provider-gcp/api/v1beta1"
 	utilconversion "sigs.k8s.io/cluster-api/util/conversion"
 	"sigs.k8s.io/controller-runtime/pkg/conversion"
@@ -30,6 +31,14 @@ func (src *GCPMachineTemplate) ConvertTo(dstRaw conversion.Hub) error { // nolin
 		return err
 	}
 
+	// Manually restore data.
+	restored := &infrav1beta1.GCPMachineTemplate{}
+	if ok, err := utilconversion.UnmarshalData(src, restored); err != nil || !ok {
+		return err
+	}
+
+	dst.Spec.Template.ObjectMeta = restored.Spec.Template.ObjectMeta
+
 	return nil
 }
 
@@ -59,3 +68,8 @@ func (dst *GCPMachineTemplateList) ConvertFrom(srcRaw conversion.Hub) error { //
 	src := srcRaw.(*infrav1beta1.GCPMachineTemplateList)
 	return Convert_v1beta1_GCPMachineTemplateList_To_v1alpha4_GCPMachineTemplateList(src, dst, nil)
 }
+
+func Convert_v1beta1_GCPMachineTemplateResource_To_v1alpha4_GCPMachineTemplateResource(in *infrav1beta1.GCPMachineTemplateResource, out *GCPMachineTemplateResource, s apiconversion.Scope) error {
+	// NOTE: custom conversion func is required because spec.template.metadata has been added in v1beta1.
+	return autoConvert_v1beta1_GCPMachineTemplateResource_To_v1alpha4_GCPMachineTemplateResource(in, out, s)
+}

api/v1beta1/gcpclustertemplate_conversion.go

@@ -0,0 +1,23 @@
+/*
+Copyright 2022 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
+
+// Hub marks GCPClusterTemplate as a conversion hub.
+func (*GCPClusterTemplate) Hub() {}
+
+// Hub marks GCPClusterTemplateList as a conversion hub.
+func (*GCPClusterTemplateList) Hub() {}

api/v1beta1/gcpclustertemplate_types.go

@@ -18,6 +18,7 @@ package v1beta1
 
 import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
 )
 
 // GCPClusterTemplateSpec defines the desired state of GCPClusterTemplate.
@@ -27,6 +28,11 @@ type GCPClusterTemplateSpec struct {
 
 // GCPClusterTemplateResource contains spec for GCPClusterSpec.
 type GCPClusterTemplateResource struct {
+	// Standard object's metadata.
+	// More info: https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata
+	// +optional
+	ObjectMeta clusterv1.ObjectMeta `json:"metadata,omitempty"`
+
 	Spec GCPClusterSpec `json:"spec"`
 }