ref.go

Documentation: k8s.io/client-go/tools/reference

     1  /*
     2  Copyright 2014 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package reference
    18  
    19  import (
    20  	"errors"
    21  	"fmt"
    22  
    23  	"k8s.io/api/core/v1"
    24  	"k8s.io/apimachinery/pkg/api/meta"
    25  	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    26  	"k8s.io/apimachinery/pkg/runtime"
    27  )
    28  
    29  var (
    30  	// Errors that could be returned by GetReference.
    31  	ErrNilObject = errors.New("can't reference a nil object")
    32  )
    33  
    34  // GetReference returns an ObjectReference which refers to the given
    35  // object, or an error if the object doesn't follow the conventions
    36  // that would allow this.
    37  // TODO: should take a meta.Interface see https://issue.k8s.io/7127
    38  func GetReference(scheme *runtime.Scheme, obj runtime.Object) (*v1.ObjectReference, error) {
    39  	if obj == nil {
    40  		return nil, ErrNilObject
    41  	}
    42  	if ref, ok := obj.(*v1.ObjectReference); ok {
    43  		// Don't make a reference to a reference.
    44  		return ref, nil
    45  	}
    46  
    47  	// An object that implements only List has enough metadata to build a reference
    48  	var listMeta metav1.Common
    49  	objectMeta, err := meta.Accessor(obj)
    50  	if err != nil {
    51  		listMeta, err = meta.CommonAccessor(obj)
    52  		if err != nil {
    53  			return nil, err
    54  		}
    55  	} else {
    56  		listMeta = objectMeta
    57  	}
    58  
    59  	gvk := obj.GetObjectKind().GroupVersionKind()
    60  
    61  	// If object meta doesn't contain data about kind and/or version,
    62  	// we are falling back to scheme.
    63  	//
    64  	// TODO: This doesn't work for CRDs, which are not registered in scheme.
    65  	if gvk.Empty() {
    66  		gvks, _, err := scheme.ObjectKinds(obj)
    67  		if err != nil {
    68  			return nil, err
    69  		}
    70  		if len(gvks) == 0 || gvks[0].Empty() {
    71  			return nil, fmt.Errorf("unexpected gvks registered for object %T: %v", obj, gvks)
    72  		}
    73  		// TODO: The same object can be registered for multiple group versions
    74  		// (although in practise this doesn't seem to be used).
    75  		// In such case, the version set may not be correct.
    76  		gvk = gvks[0]
    77  	}
    78  
    79  	kind := gvk.Kind
    80  	version := gvk.GroupVersion().String()
    81  
    82  	// only has list metadata
    83  	if objectMeta == nil {
    84  		return &v1.ObjectReference{
    85  			Kind:            kind,
    86  			APIVersion:      version,
    87  			ResourceVersion: listMeta.GetResourceVersion(),
    88  		}, nil
    89  	}
    90  
    91  	return &v1.ObjectReference{
    92  		Kind:            kind,
    93  		APIVersion:      version,
    94  		Name:            objectMeta.GetName(),
    95  		Namespace:       objectMeta.GetNamespace(),
    96  		UID:             objectMeta.GetUID(),
    97  		ResourceVersion: objectMeta.GetResourceVersion(),
    98  	}, nil
    99  }
   100  
   101  // GetPartialReference is exactly like GetReference, but allows you to set the FieldPath.
   102  func GetPartialReference(scheme *runtime.Scheme, obj runtime.Object, fieldPath string) (*v1.ObjectReference, error) {
   103  	ref, err := GetReference(scheme, obj)
   104  	if err != nil {
   105  		return nil, err
   106  	}
   107  	ref.FieldPath = fieldPath
   108  	return ref, nil
   109  }
   110
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