Merge pull request kubernetes-sigs#9045 from JoelSpeed/drop-schemebuilder-pattern

🌱 Remove reliance on controller-runtime scheme builder

Author: k8s-ci-robot

api/v1beta1/cluster_types.go

@@ -599,7 +599,7 @@ type ClusterList struct {
 }
 
 func init() {
-	SchemeBuilder.Register(&Cluster{}, &ClusterList{})
+	objectTypes = append(objectTypes, &Cluster{}, &ClusterList{})
 }
 
 // FailureDomains is a slice of FailureDomains.

api/v1beta1/clusterclass_types.go

@@ -706,5 +706,5 @@ type ClusterClassList struct {
 }
 
 func init() {
-	SchemeBuilder.Register(&ClusterClass{}, &ClusterClassList{})
+	objectTypes = append(objectTypes, &ClusterClass{}, &ClusterClassList{})
 }

api/v1beta1/groupversion_info.go

@@ -20,17 +20,26 @@ limitations under the License.
 package v1beta1
 
 import (
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-	"sigs.k8s.io/controller-runtime/pkg/scheme"
 )
 
 var (
 	// GroupVersion is group version used to register these objects.
 	GroupVersion = schema.GroupVersion{Group: "cluster.x-k8s.io", Version: "v1beta1"}
 
-	// SchemeBuilder is used to add go types to the GroupVersionKind scheme.
-	SchemeBuilder = &scheme.Builder{GroupVersion: GroupVersion}
+	// schemeBuilder is used to add go types to the GroupVersionKind scheme.
+	schemeBuilder = runtime.NewSchemeBuilder(addKnownTypes)
 
 	// AddToScheme adds the types in this group-version to the given scheme.
-	AddToScheme = SchemeBuilder.AddToScheme
+	AddToScheme = schemeBuilder.AddToScheme
+
+	objectTypes = []runtime.Object{}
 )
+
+func addKnownTypes(scheme *runtime.Scheme) error {
+	scheme.AddKnownTypes(GroupVersion, objectTypes...)
+	metav1.AddToGroupVersion(scheme, GroupVersion)
+	return nil
+}

api/v1beta1/machine_types.go

@@ -307,5 +307,5 @@ type MachineList struct {
 }
 
 func init() {
-	SchemeBuilder.Register(&Machine{}, &MachineList{})
+	objectTypes = append(objectTypes, &Machine{}, &MachineList{})
 }

api/v1beta1/machinedeployment_types.go

@@ -337,7 +337,7 @@ type MachineDeploymentList struct {
 }
 
 func init() {
-	SchemeBuilder.Register(&MachineDeployment{}, &MachineDeploymentList{})
+	objectTypes = append(objectTypes, &MachineDeployment{}, &MachineDeploymentList{})
 }
 
 // GetConditions returns the set of conditions for the machinedeployment.

api/v1beta1/machinedeployment_webhook_test.go

@@ -24,6 +24,7 @@ import (
 	. "github.com/onsi/gomega"
 	admissionv1 "k8s.io/api/admission/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
 	"k8s.io/utils/pointer"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
@@ -45,8 +46,8 @@ func TestMachineDeploymentDefault(t *testing.T) {
 		},
 	}
 
-	scheme, err := SchemeBuilder.Build()
-	g.Expect(err).ToNot(HaveOccurred())
+	scheme := runtime.NewScheme()
+	g.Expect(AddToScheme(scheme)).To(Succeed())
 	defaulter := MachineDeploymentDefaulter(scheme)
 
 	t.Run("for MachineDeployment", defaultValidateTestCustomDefaulter(md, defaulter))

api/v1beta1/machinehealthcheck_types.go

@@ -169,5 +169,5 @@ type MachineHealthCheckList struct {
 }
 
 func init() {
-	SchemeBuilder.Register(&MachineHealthCheck{}, &MachineHealthCheckList{})
+	objectTypes = append(objectTypes, &MachineHealthCheck{}, &MachineHealthCheckList{})
 }

api/v1beta1/machineset_types.go

@@ -240,5 +240,5 @@ type MachineSetList struct {
 }
 
 func init() {
-	SchemeBuilder.Register(&MachineSet{}, &MachineSetList{})
+	objectTypes = append(objectTypes, &MachineSet{}, &MachineSetList{})
 }

docs/book/src/developer/providers/implementers-guide/create_api.md

@@ -62,3 +62,68 @@ As the deleted comments request, run `make manager manifests` to regenerate some
 git add .
 git commit -m "Added cluster types"
 ```
+
+# Registering APIs in the scheme
+
+To enable clients to encode and decode your API, your types must be able to be registered within a [scheme].
+
+[scheme]: https://pkg.go.dev/k8s.io/apimachinery/pkg/runtime#Scheme
+
+By default, Kubebuilder will provide you with a scheme builder like:
+
+```go
+import "sigs.k8s.io/controller-runtime/pkg/scheme"
+
+var (
+	// SchemeBuilder is used to add go types to the GroupVersionKind scheme
+	SchemeBuilder = &scheme.Builder{GroupVersion: GroupVersion}
+
+	// AddToScheme adds the types in this group-version to the given scheme.
+	AddToScheme = SchemeBuilder.AddToScheme
+)
+```
+
+and scheme registration that looks like:
+
+```go
+func init() {
+	SchemeBuilder.Register(&Captain{}, &CaptainList{})
+}
+```
+
+This pattern introduces a dependency on controller-runtime to your API types, which is discouraged for
+API packages as it makes it more difficult for consumers of your API to import your API types.
+In general, you should minimise the imports within the API folder of your package to allow your API types
+to be imported cleanly into other projects.
+
+To mitigate this, use the following schemebuilder pattern:
+
+```go
+import "k8s.io/apimachinery/pkg/runtime"
+
+var (
+	// schemeBuilder is used to add go types to the GroupVersionKind scheme.
+	schemeBuilder = runtime.NewSchemeBuilder(addKnownTypes)
+
+	// AddToScheme adds the types in this group-version to the given scheme.
+	AddToScheme = schemeBuilder.AddToScheme
+
+	objectTypes = []runtime.Object{}
+)
+
+func addKnownTypes(scheme *runtime.Scheme) error {
+	scheme.AddKnownTypes(GroupVersion, objectTypes...)
+	metav1.AddToGroupVersion(scheme, GroupVersion)
+	return nil
+}
+```
+
+and register types as below:
+
+```go
+func init() {
+	objectTypes = append(objectTypes, &Captain{}, &CaptainList{})
+}
+```
+
+This pattern reduces the number of dependencies being introduced into the API package within your project.

internal/test/builder/builders.go

@@ -25,6 +25,7 @@ import (
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/intstr"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
@@ -1268,8 +1269,8 @@ func (m *MachineDeploymentBuilder) Build() *clusterv1.MachineDeployment {
 		}
 	}
 	if m.defaulter {
-		scheme, err := clusterv1.SchemeBuilder.Build()
-		if err != nil {
+		scheme := runtime.NewScheme()
+		if err := clusterv1.AddToScheme(scheme); err != nil {
 			panic(err)
 		}
 		ctx := admission.NewContextWithRequest(context.Background(), admission.Request{