(feat) Add auto-discovery in k8s | Adarsh

vendor/k8s.io/client-go/tools/reference/ref.go

@@ -0,0 +1,109 @@
+/*
+Copyright 2014 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 reference
+
+import (
+	"errors"
+	"fmt"
+
+	"k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/meta"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+)
+
+var (
+	// Errors that could be returned by GetReference.
+	ErrNilObject = errors.New("can't reference a nil object")
+)
+
+// GetReference returns an ObjectReference which refers to the given
+// object, or an error if the object doesn't follow the conventions
+// that would allow this.
+// TODO: should take a meta.Interface see http://issue.k8s.io/7127
+func GetReference(scheme *runtime.Scheme, obj runtime.Object) (*v1.ObjectReference, error) {
+	if obj == nil {
+		return nil, ErrNilObject
+	}
+	if ref, ok := obj.(*v1.ObjectReference); ok {
+		// Don't make a reference to a reference.
+		return ref, nil
+	}
+
+	// An object that implements only List has enough metadata to build a reference
+	var listMeta metav1.Common
+	objectMeta, err := meta.Accessor(obj)
+	if err != nil {
+		listMeta, err = meta.CommonAccessor(obj)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		listMeta = objectMeta
+	}
+
+	gvk := obj.GetObjectKind().GroupVersionKind()
+
+	// If object meta doesn't contain data about kind and/or version,
+	// we are falling back to scheme.
+	//
+	// TODO: This doesn't work for CRDs, which are not registered in scheme.
+	if gvk.Empty() {
+		gvks, _, err := scheme.ObjectKinds(obj)
+		if err != nil {
+			return nil, err
+		}
+		if len(gvks) == 0 || gvks[0].Empty() {
+			return nil, fmt.Errorf("unexpected gvks registered for object %T: %v", obj, gvks)
+		}
+		// TODO: The same object can be registered for multiple group versions
+		// (although in practise this doesn't seem to be used).
+		// In such case, the version set may not be correct.
+		gvk = gvks[0]
+	}
+
+	kind := gvk.Kind
+	version := gvk.GroupVersion().String()
+
+	// only has list metadata
+	if objectMeta == nil {
+		return &v1.ObjectReference{
+			Kind:            kind,
+			APIVersion:      version,
+			ResourceVersion: listMeta.GetResourceVersion(),
+		}, nil
+	}
+
+	return &v1.ObjectReference{
+		Kind:            kind,
+		APIVersion:      version,
+		Name:            objectMeta.GetName(),
+		Namespace:       objectMeta.GetNamespace(),
+		UID:             objectMeta.GetUID(),
+		ResourceVersion: objectMeta.GetResourceVersion(),
+	}, nil
+}
+
+// GetPartialReference is exactly like GetReference, but allows you to set the FieldPath.
+func GetPartialReference(scheme *runtime.Scheme, obj runtime.Object, fieldPath string) (*v1.ObjectReference, error) {
+	ref, err := GetReference(scheme, obj)
+	if err != nil {
+		return nil, err
+	}
+	ref.FieldPath = fieldPath
+	return ref, nil
+}