github.com/aclisp/heapster@v0.19.2-0.20160613100040-51756f899a96/Godeps/_workspace/src/k8s.io/kubernetes/pkg/api/ref.go (about)

     1  /*
     2  Copyright 2014 The Kubernetes Authors All rights reserved.
     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 api
    18  
    19  import (
    20  	"errors"
    21  	"fmt"
    22  	"net/url"
    23  	"strings"
    24  
    25  	"k8s.io/kubernetes/pkg/api/meta"
    26  	"k8s.io/kubernetes/pkg/api/unversioned"
    27  	"k8s.io/kubernetes/pkg/runtime"
    28  )
    29  
    30  var (
    31  	// Errors that could be returned by GetReference.
    32  	ErrNilObject  = errors.New("can't reference a nil object")
    33  	ErrNoSelfLink = errors.New("selfLink was empty, can't make reference")
    34  )
    35  
    36  // GetReference returns an ObjectReference which refers to the given
    37  // object, or an error if the object doesn't follow the conventions
    38  // that would allow this.
    39  // TODO: should take a meta.Interface see http://issue.k8s.io/7127
    40  func GetReference(obj runtime.Object) (*ObjectReference, error) {
    41  	if obj == nil {
    42  		return nil, ErrNilObject
    43  	}
    44  	if ref, ok := obj.(*ObjectReference); ok {
    45  		// Don't make a reference to a reference.
    46  		return ref, nil
    47  	}
    48  	meta, err := meta.Accessor(obj)
    49  	if err != nil {
    50  		return nil, err
    51  	}
    52  
    53  	gvk := obj.GetObjectKind().GroupVersionKind()
    54  
    55  	// if the object referenced is actually persisted, we can just get kind from meta
    56  	// if we are building an object reference to something not yet persisted, we should fallback to scheme
    57  	kind := gvk.Kind
    58  	if len(kind) == 0 {
    59  		// TODO: this is wrong
    60  		gvk, err := Scheme.ObjectKind(obj)
    61  		if err != nil {
    62  			return nil, err
    63  		}
    64  		kind = gvk.Kind
    65  	}
    66  
    67  	// if the object referenced is actually persisted, we can also get version from meta
    68  	version := gvk.GroupVersion().String()
    69  	if len(version) == 0 {
    70  		selfLink := meta.GetSelfLink()
    71  		if len(selfLink) == 0 {
    72  			return nil, ErrNoSelfLink
    73  		}
    74  		selfLinkUrl, err := url.Parse(selfLink)
    75  		if err != nil {
    76  			return nil, err
    77  		}
    78  		// example paths: /<prefix>/<version>/*
    79  		parts := strings.Split(selfLinkUrl.Path, "/")
    80  		if len(parts) < 3 {
    81  			return nil, fmt.Errorf("unexpected self link format: '%v'; got version '%v'", selfLink, version)
    82  		}
    83  		version = parts[2]
    84  	}
    85  
    86  	return &ObjectReference{
    87  		Kind:            kind,
    88  		APIVersion:      version,
    89  		Name:            meta.GetName(),
    90  		Namespace:       meta.GetNamespace(),
    91  		UID:             meta.GetUID(),
    92  		ResourceVersion: meta.GetResourceVersion(),
    93  	}, nil
    94  }
    95  
    96  // GetPartialReference is exactly like GetReference, but allows you to set the FieldPath.
    97  func GetPartialReference(obj runtime.Object, fieldPath string) (*ObjectReference, error) {
    98  	ref, err := GetReference(obj)
    99  	if err != nil {
   100  		return nil, err
   101  	}
   102  	ref.FieldPath = fieldPath
   103  	return ref, nil
   104  }
   105  
   106  // IsAnAPIObject allows clients to preemptively get a reference to an API object and pass it to places that
   107  // intend only to get a reference to that object. This simplifies the event recording interface.
   108  func (obj *ObjectReference) SetGroupVersionKind(gvk unversioned.GroupVersionKind) {
   109  	obj.APIVersion, obj.Kind = gvk.ToAPIVersionAndKind()
   110  }
   111  func (obj *ObjectReference) GroupVersionKind() unversioned.GroupVersionKind {
   112  	return unversioned.FromAPIVersionAndKind(obj.APIVersion, obj.Kind)
   113  }