github.com/timstclair/heapster@v0.20.0-alpha1/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/runtime" 27 ) 28 29 var ( 30 // Errors that could be returned by GetReference. 31 ErrNilObject = errors.New("can't reference a nil object") 32 ErrNoSelfLink = errors.New("selfLink was empty, can't make reference") 33 ) 34 35 // GetReference returns an ObjectReference which refers to the given 36 // object, or an error if the object doesn't follow the conventions 37 // that would allow this. 38 // TODO: should take a meta.Interface see http://issue.k8s.io/7127 39 func GetReference(obj runtime.Object) (*ObjectReference, error) { 40 if obj == nil { 41 return nil, ErrNilObject 42 } 43 if ref, ok := obj.(*ObjectReference); ok { 44 // Don't make a reference to a reference. 45 return ref, nil 46 } 47 meta, err := meta.Accessor(obj) 48 if err != nil { 49 return nil, err 50 } 51 52 // if the object referenced is actually persisted, we can just get kind from meta 53 // if we are building an object reference to something not yet persisted, we should fallback to scheme 54 kind := meta.Kind() 55 if kind == "" { 56 _, kind, err = Scheme.ObjectVersionAndKind(obj) 57 if err != nil { 58 return nil, err 59 } 60 } 61 62 // if the object referenced is actually persisted, we can also get version from meta 63 version := meta.APIVersion() 64 if version == "" { 65 selfLink := meta.SelfLink() 66 if selfLink == "" { 67 return nil, ErrNoSelfLink 68 } else { 69 selfLinkUrl, err := url.Parse(selfLink) 70 if err != nil { 71 return nil, err 72 } 73 // example paths: /<prefix>/<version>/* 74 parts := strings.Split(selfLinkUrl.Path, "/") 75 if len(parts) < 3 { 76 return nil, fmt.Errorf("unexpected self link format: '%v'; got version '%v'", selfLink, version) 77 } 78 version = parts[2] 79 } 80 } 81 82 return &ObjectReference{ 83 Kind: kind, 84 APIVersion: version, 85 Name: meta.Name(), 86 Namespace: meta.Namespace(), 87 UID: meta.UID(), 88 ResourceVersion: meta.ResourceVersion(), 89 }, nil 90 } 91 92 // GetPartialReference is exactly like GetReference, but allows you to set the FieldPath. 93 func GetPartialReference(obj runtime.Object, fieldPath string) (*ObjectReference, error) { 94 ref, err := GetReference(obj) 95 if err != nil { 96 return nil, err 97 } 98 ref.FieldPath = fieldPath 99 return ref, nil 100 } 101 102 // IsAnAPIObject allows clients to preemptively get a reference to an API object and pass it to places that 103 // intend only to get a reference to that object. This simplifies the event recording interface. 104 func (*ObjectReference) IsAnAPIObject() {}