summaryrefslogtreecommitdiff
path: root/vendor/k8s.io/apimachinery/pkg/runtime/scheme.go
blob: 3b254961d7a4615cfb2dbe871e0f98f85b7c53ab (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
/*
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 runtime

import (
	"fmt"
	"net/url"
	"reflect"
	"strings"

	"k8s.io/apimachinery/pkg/conversion"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/util/naming"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/sets"
)

// Scheme defines methods for serializing and deserializing API objects, a type
// registry for converting group, version, and kind information to and from Go
// schemas, and mappings between Go schemas of different versions. A scheme is the
// foundation for a versioned API and versioned configuration over time.
//
// In a Scheme, a Type is a particular Go struct, a Version is a point-in-time
// identifier for a particular representation of that Type (typically backwards
// compatible), a Kind is the unique name for that Type within the Version, and a
// Group identifies a set of Versions, Kinds, and Types that evolve over time. An
// Unversioned Type is one that is not yet formally bound to a type and is promised
// to be backwards compatible (effectively a "v1" of a Type that does not expect
// to break in the future).
//
// Schemes are not expected to change at runtime and are only threadsafe after
// registration is complete.
type Scheme struct {
	// versionMap allows one to figure out the go type of an object with
	// the given version and name.
	gvkToType map[schema.GroupVersionKind]reflect.Type

	// typeToGroupVersion allows one to find metadata for a given go object.
	// The reflect.Type we index by should *not* be a pointer.
	typeToGVK map[reflect.Type][]schema.GroupVersionKind

	// unversionedTypes are transformed without conversion in ConvertToVersion.
	unversionedTypes map[reflect.Type]schema.GroupVersionKind

	// unversionedKinds are the names of kinds that can be created in the context of any group
	// or version
	// TODO: resolve the status of unversioned types.
	unversionedKinds map[string]reflect.Type

	// Map from version and resource to the corresponding func to convert
	// resource field labels in that version to internal version.
	fieldLabelConversionFuncs map[schema.GroupVersionKind]FieldLabelConversionFunc

	// defaulterFuncs is an array of interfaces to be called with an object to provide defaulting
	// the provided object must be a pointer.
	defaulterFuncs map[reflect.Type]func(interface{})

	// converter stores all registered conversion functions. It also has
	// default converting behavior.
	converter *conversion.Converter

	// versionPriority is a map of groups to ordered lists of versions for those groups indicating the
	// default priorities of these versions as registered in the scheme
	versionPriority map[string][]string

	// observedVersions keeps track of the order we've seen versions during type registration
	observedVersions []schema.GroupVersion

	// schemeName is the name of this scheme.  If you don't specify a name, the stack of the NewScheme caller will be used.
	// This is useful for error reporting to indicate the origin of the scheme.
	schemeName string
}

// FieldLabelConversionFunc converts a field selector to internal representation.
type FieldLabelConversionFunc func(label, value string) (internalLabel, internalValue string, err error)

// NewScheme creates a new Scheme. This scheme is pluggable by default.
func NewScheme() *Scheme {
	s := &Scheme{
		gvkToType:                 map[schema.GroupVersionKind]reflect.Type{},
		typeToGVK:                 map[reflect.Type][]schema.GroupVersionKind{},
		unversionedTypes:          map[reflect.Type]schema.GroupVersionKind{},
		unversionedKinds:          map[string]reflect.Type{},
		fieldLabelConversionFuncs: map[schema.GroupVersionKind]FieldLabelConversionFunc{},
		defaulterFuncs:            map[reflect.Type]func(interface{}){},
		versionPriority:           map[string][]string{},
		schemeName:                naming.GetNameFromCallsite(internalPackages...),
	}
	s.converter = conversion.NewConverter(s.nameFunc)

	// Enable couple default conversions by default.
	utilruntime.Must(RegisterEmbeddedConversions(s))
	utilruntime.Must(RegisterStringConversions(s))

	utilruntime.Must(s.RegisterInputDefaults(&map[string][]string{}, JSONKeyMapper, conversion.AllowDifferentFieldTypeNames|conversion.IgnoreMissingFields))
	utilruntime.Must(s.RegisterInputDefaults(&url.Values{}, JSONKeyMapper, conversion.AllowDifferentFieldTypeNames|conversion.IgnoreMissingFields))
	return s
}

// nameFunc returns the name of the type that we wish to use to determine when two types attempt
// a conversion. Defaults to the go name of the type if the type is not registered.
func (s *Scheme) nameFunc(t reflect.Type) string {
	// find the preferred names for this type
	gvks, ok := s.typeToGVK[t]
	if !ok {
		return t.Name()
	}

	for _, gvk := range gvks {
		internalGV := gvk.GroupVersion()
		internalGV.Version = APIVersionInternal // this is hacky and maybe should be passed in
		internalGVK := internalGV.WithKind(gvk.Kind)

		if internalType, exists := s.gvkToType[internalGVK]; exists {
			return s.typeToGVK[internalType][0].Kind
		}
	}

	return gvks[0].Kind
}

// fromScope gets the input version, desired output version, and desired Scheme
// from a conversion.Scope.
func (s *Scheme) fromScope(scope conversion.Scope) *Scheme {
	return s
}

// Converter allows access to the converter for the scheme
func (s *Scheme) Converter() *conversion.Converter {
	return s.converter
}

// AddUnversionedTypes registers the provided types as "unversioned", which means that they follow special rules.
// Whenever an object of this type is serialized, it is serialized with the provided group version and is not
// converted. Thus unversioned objects are expected to remain backwards compatible forever, as if they were in an
// API group and version that would never be updated.
//
// TODO: there is discussion about removing unversioned and replacing it with objects that are manifest into
//   every version with particular schemas. Resolve this method at that point.
func (s *Scheme) AddUnversionedTypes(version schema.GroupVersion, types ...Object) {
	s.addObservedVersion(version)
	s.AddKnownTypes(version, types...)
	for _, obj := range types {
		t := reflect.TypeOf(obj).Elem()
		gvk := version.WithKind(t.Name())
		s.unversionedTypes[t] = gvk
		if old, ok := s.unversionedKinds[gvk.Kind]; ok && t != old {
			panic(fmt.Sprintf("%v.%v has already been registered as unversioned kind %q - kind name must be unique in scheme %q", old.PkgPath(), old.Name(), gvk, s.schemeName))
		}
		s.unversionedKinds[gvk.Kind] = t
	}
}

// AddKnownTypes registers all types passed in 'types' as being members of version 'version'.
// All objects passed to types should be pointers to structs. The name that go reports for
// the struct becomes the "kind" field when encoding. Version may not be empty - use the
// APIVersionInternal constant if you have a type that does not have a formal version.
func (s *Scheme) AddKnownTypes(gv schema.GroupVersion, types ...Object) {
	s.addObservedVersion(gv)
	for _, obj := range types {
		t := reflect.TypeOf(obj)
		if t.Kind() != reflect.Ptr {
			panic("All types must be pointers to structs.")
		}
		t = t.Elem()
		s.AddKnownTypeWithName(gv.WithKind(t.Name()), obj)
	}
}

// AddKnownTypeWithName is like AddKnownTypes, but it lets you specify what this type should
// be encoded as. Useful for testing when you don't want to make multiple packages to define
// your structs. Version may not be empty - use the APIVersionInternal constant if you have a
// type that does not have a formal version.
func (s *Scheme) AddKnownTypeWithName(gvk schema.GroupVersionKind, obj Object) {
	s.addObservedVersion(gvk.GroupVersion())
	t := reflect.TypeOf(obj)
	if len(gvk.Version) == 0 {
		panic(fmt.Sprintf("version is required on all types: %s %v", gvk, t))
	}
	if t.Kind() != reflect.Ptr {
		panic("All types must be pointers to structs.")
	}
	t = t.Elem()
	if t.Kind() != reflect.Struct {
		panic("All types must be pointers to structs.")
	}

	if oldT, found := s.gvkToType[gvk]; found && oldT != t {
		panic(fmt.Sprintf("Double registration of different types for %v: old=%v.%v, new=%v.%v in scheme %q", gvk, oldT.PkgPath(), oldT.Name(), t.PkgPath(), t.Name(), s.schemeName))
	}

	s.gvkToType[gvk] = t

	for _, existingGvk := range s.typeToGVK[t] {
		if existingGvk == gvk {
			return
		}
	}
	s.typeToGVK[t] = append(s.typeToGVK[t], gvk)

	// if the type implements DeepCopyInto(<obj>), register a self-conversion
	if m := reflect.ValueOf(obj).MethodByName("DeepCopyInto"); m.IsValid() && m.Type().NumIn() == 1 && m.Type().NumOut() == 0 && m.Type().In(0) == reflect.TypeOf(obj) {
		if err := s.AddGeneratedConversionFunc(obj, obj, func(a, b interface{}, scope conversion.Scope) error {
			// copy a to b
			reflect.ValueOf(a).MethodByName("DeepCopyInto").Call([]reflect.Value{reflect.ValueOf(b)})
			// clear TypeMeta to match legacy reflective conversion
			b.(Object).GetObjectKind().SetGroupVersionKind(schema.GroupVersionKind{})
			return nil
		}); err != nil {
			panic(err)
		}
	}
}

// KnownTypes returns the types known for the given version.
func (s *Scheme) KnownTypes(gv schema.GroupVersion) map[string]reflect.Type {
	types := make(map[string]reflect.Type)
	for gvk, t := range s.gvkToType {
		if gv != gvk.GroupVersion() {
			continue
		}

		types[gvk.Kind] = t
	}
	return types
}

// AllKnownTypes returns the all known types.
func (s *Scheme) AllKnownTypes() map[schema.GroupVersionKind]reflect.Type {
	return s.gvkToType
}

// ObjectKinds returns all possible group,version,kind of the go object, true if the
// object is considered unversioned, or an error if it's not a pointer or is unregistered.
func (s *Scheme) ObjectKinds(obj Object) ([]schema.GroupVersionKind, bool, error) {
	// Unstructured objects are always considered to have their declared GVK
	if _, ok := obj.(Unstructured); ok {
		// we require that the GVK be populated in order to recognize the object
		gvk := obj.GetObjectKind().GroupVersionKind()
		if len(gvk.Kind) == 0 {
			return nil, false, NewMissingKindErr("unstructured object has no kind")
		}
		if len(gvk.Version) == 0 {
			return nil, false, NewMissingVersionErr("unstructured object has no version")
		}
		return []schema.GroupVersionKind{gvk}, false, nil
	}

	v, err := conversion.EnforcePtr(obj)
	if err != nil {
		return nil, false, err
	}
	t := v.Type()

	gvks, ok := s.typeToGVK[t]
	if !ok {
		return nil, false, NewNotRegisteredErrForType(s.schemeName, t)
	}
	_, unversionedType := s.unversionedTypes[t]

	return gvks, unversionedType, nil
}

// Recognizes returns true if the scheme is able to handle the provided group,version,kind
// of an object.
func (s *Scheme) Recognizes(gvk schema.GroupVersionKind) bool {
	_, exists := s.gvkToType[gvk]
	return exists
}

func (s *Scheme) IsUnversioned(obj Object) (bool, bool) {
	v, err := conversion.EnforcePtr(obj)
	if err != nil {
		return false, false
	}
	t := v.Type()

	if _, ok := s.typeToGVK[t]; !ok {
		return false, false
	}
	_, ok := s.unversionedTypes[t]
	return ok, true
}

// New returns a new API object of the given version and name, or an error if it hasn't
// been registered. The version and kind fields must be specified.
func (s *Scheme) New(kind schema.GroupVersionKind) (Object, error) {
	if t, exists := s.gvkToType[kind]; exists {
		return reflect.New(t).Interface().(Object), nil
	}

	if t, exists := s.unversionedKinds[kind.Kind]; exists {
		return reflect.New(t).Interface().(Object), nil
	}
	return nil, NewNotRegisteredErrForKind(s.schemeName, kind)
}

// Log sets a logger on the scheme. For test purposes only
func (s *Scheme) Log(l conversion.DebugLogger) {
	s.converter.Debug = l
}

// AddIgnoredConversionType identifies a pair of types that should be skipped by
// conversion (because the data inside them is explicitly dropped during
// conversion).
func (s *Scheme) AddIgnoredConversionType(from, to interface{}) error {
	return s.converter.RegisterIgnoredConversion(from, to)
}

// AddConversionFunc registers a function that converts between a and b by passing objects of those
// types to the provided function. The function *must* accept objects of a and b - this machinery will not enforce
// any other guarantee.
func (s *Scheme) AddConversionFunc(a, b interface{}, fn conversion.ConversionFunc) error {
	return s.converter.RegisterUntypedConversionFunc(a, b, fn)
}

// AddGeneratedConversionFunc registers a function that converts between a and b by passing objects of those
// types to the provided function. The function *must* accept objects of a and b - this machinery will not enforce
// any other guarantee.
func (s *Scheme) AddGeneratedConversionFunc(a, b interface{}, fn conversion.ConversionFunc) error {
	return s.converter.RegisterGeneratedUntypedConversionFunc(a, b, fn)
}

// AddFieldLabelConversionFunc adds a conversion function to convert field selectors
// of the given kind from the given version to internal version representation.
func (s *Scheme) AddFieldLabelConversionFunc(gvk schema.GroupVersionKind, conversionFunc FieldLabelConversionFunc) error {
	s.fieldLabelConversionFuncs[gvk] = conversionFunc
	return nil
}

// RegisterInputDefaults sets the provided field mapping function and field matching
// as the defaults for the provided input type.  The fn may be nil, in which case no
// mapping will happen by default. Use this method to register a mechanism for handling
// a specific input type in conversion, such as a map[string]string to structs.
func (s *Scheme) RegisterInputDefaults(in interface{}, fn conversion.FieldMappingFunc, defaultFlags conversion.FieldMatchingFlags) error {
	return s.converter.RegisterInputDefaults(in, fn, defaultFlags)
}

// AddTypeDefaultingFunc registers a function that is passed a pointer to an
// object and can default fields on the object. These functions will be invoked
// when Default() is called. The function will never be called unless the
// defaulted object matches srcType. If this function is invoked twice with the
// same srcType, the fn passed to the later call will be used instead.
func (s *Scheme) AddTypeDefaultingFunc(srcType Object, fn func(interface{})) {
	s.defaulterFuncs[reflect.TypeOf(srcType)] = fn
}

// Default sets defaults on the provided Object.
func (s *Scheme) Default(src Object) {
	if fn, ok := s.defaulterFuncs[reflect.TypeOf(src)]; ok {
		fn(src)
	}
}

// Convert will attempt to convert in into out. Both must be pointers. For easy
// testing of conversion functions. Returns an error if the conversion isn't
// possible. You can call this with types that haven't been registered (for example,
// a to test conversion of types that are nested within registered types). The
// context interface is passed to the convertor. Convert also supports Unstructured
// types and will convert them intelligently.
func (s *Scheme) Convert(in, out interface{}, context interface{}) error {
	unstructuredIn, okIn := in.(Unstructured)
	unstructuredOut, okOut := out.(Unstructured)
	switch {
	case okIn && okOut:
		// converting unstructured input to an unstructured output is a straight copy - unstructured
		// is a "smart holder" and the contents are passed by reference between the two objects
		unstructuredOut.SetUnstructuredContent(unstructuredIn.UnstructuredContent())
		return nil

	case okOut:
		// if the output is an unstructured object, use the standard Go type to unstructured
		// conversion. The object must not be internal.
		obj, ok := in.(Object)
		if !ok {
			return fmt.Errorf("unable to convert object type %T to Unstructured, must be a runtime.Object", in)
		}
		gvks, unversioned, err := s.ObjectKinds(obj)
		if err != nil {
			return err
		}
		gvk := gvks[0]

		// if no conversion is necessary, convert immediately
		if unversioned || gvk.Version != APIVersionInternal {
			content, err := DefaultUnstructuredConverter.ToUnstructured(in)
			if err != nil {
				return err
			}
			unstructuredOut.SetUnstructuredContent(content)
			unstructuredOut.GetObjectKind().SetGroupVersionKind(gvk)
			return nil
		}

		// attempt to convert the object to an external version first.
		target, ok := context.(GroupVersioner)
		if !ok {
			return fmt.Errorf("unable to convert the internal object type %T to Unstructured without providing a preferred version to convert to", in)
		}
		// Convert is implicitly unsafe, so we don't need to perform a safe conversion
		versioned, err := s.UnsafeConvertToVersion(obj, target)
		if err != nil {
			return err
		}
		content, err := DefaultUnstructuredConverter.ToUnstructured(versioned)
		if err != nil {
			return err
		}
		unstructuredOut.SetUnstructuredContent(content)
		return nil

	case okIn:
		// converting an unstructured object to any type is modeled by first converting
		// the input to a versioned type, then running standard conversions
		typed, err := s.unstructuredToTyped(unstructuredIn)
		if err != nil {
			return err
		}
		in = typed
	}

	flags, meta := s.generateConvertMeta(in)
	meta.Context = context
	if flags == 0 {
		flags = conversion.AllowDifferentFieldTypeNames
	}
	return s.converter.Convert(in, out, flags, meta)
}

// ConvertFieldLabel alters the given field label and value for an kind field selector from
// versioned representation to an unversioned one or returns an error.
func (s *Scheme) ConvertFieldLabel(gvk schema.GroupVersionKind, label, value string) (string, string, error) {
	conversionFunc, ok := s.fieldLabelConversionFuncs[gvk]
	if !ok {
		return DefaultMetaV1FieldSelectorConversion(label, value)
	}
	return conversionFunc(label, value)
}

// ConvertToVersion attempts to convert an input object to its matching Kind in another
// version within this scheme. Will return an error if the provided version does not
// contain the inKind (or a mapping by name defined with AddKnownTypeWithName). Will also
// return an error if the conversion does not result in a valid Object being
// returned. Passes target down to the conversion methods as the Context on the scope.
func (s *Scheme) ConvertToVersion(in Object, target GroupVersioner) (Object, error) {
	return s.convertToVersion(true, in, target)
}

// UnsafeConvertToVersion will convert in to the provided target if such a conversion is possible,
// but does not guarantee the output object does not share fields with the input object. It attempts to be as
// efficient as possible when doing conversion.
func (s *Scheme) UnsafeConvertToVersion(in Object, target GroupVersioner) (Object, error) {
	return s.convertToVersion(false, in, target)
}

// convertToVersion handles conversion with an optional copy.
func (s *Scheme) convertToVersion(copy bool, in Object, target GroupVersioner) (Object, error) {
	var t reflect.Type

	if u, ok := in.(Unstructured); ok {
		typed, err := s.unstructuredToTyped(u)
		if err != nil {
			return nil, err
		}

		in = typed
		// unstructuredToTyped returns an Object, which must be a pointer to a struct.
		t = reflect.TypeOf(in).Elem()

	} else {
		// determine the incoming kinds with as few allocations as possible.
		t = reflect.TypeOf(in)
		if t.Kind() != reflect.Ptr {
			return nil, fmt.Errorf("only pointer types may be converted: %v", t)
		}
		t = t.Elem()
		if t.Kind() != reflect.Struct {
			return nil, fmt.Errorf("only pointers to struct types may be converted: %v", t)
		}
	}

	kinds, ok := s.typeToGVK[t]
	if !ok || len(kinds) == 0 {
		return nil, NewNotRegisteredErrForType(s.schemeName, t)
	}

	gvk, ok := target.KindForGroupVersionKinds(kinds)
	if !ok {
		// try to see if this type is listed as unversioned (for legacy support)
		// TODO: when we move to server API versions, we should completely remove the unversioned concept
		if unversionedKind, ok := s.unversionedTypes[t]; ok {
			if gvk, ok := target.KindForGroupVersionKinds([]schema.GroupVersionKind{unversionedKind}); ok {
				return copyAndSetTargetKind(copy, in, gvk)
			}
			return copyAndSetTargetKind(copy, in, unversionedKind)
		}
		return nil, NewNotRegisteredErrForTarget(s.schemeName, t, target)
	}

	// target wants to use the existing type, set kind and return (no conversion necessary)
	for _, kind := range kinds {
		if gvk == kind {
			return copyAndSetTargetKind(copy, in, gvk)
		}
	}

	// type is unversioned, no conversion necessary
	if unversionedKind, ok := s.unversionedTypes[t]; ok {
		if gvk, ok := target.KindForGroupVersionKinds([]schema.GroupVersionKind{unversionedKind}); ok {
			return copyAndSetTargetKind(copy, in, gvk)
		}
		return copyAndSetTargetKind(copy, in, unversionedKind)
	}

	out, err := s.New(gvk)
	if err != nil {
		return nil, err
	}

	if copy {
		in = in.DeepCopyObject()
	}

	flags, meta := s.generateConvertMeta(in)
	meta.Context = target
	if err := s.converter.Convert(in, out, flags, meta); err != nil {
		return nil, err
	}

	setTargetKind(out, gvk)
	return out, nil
}

// unstructuredToTyped attempts to transform an unstructured object to a typed
// object if possible. It will return an error if conversion is not possible, or the versioned
// Go form of the object. Note that this conversion will lose fields.
func (s *Scheme) unstructuredToTyped(in Unstructured) (Object, error) {
	// the type must be something we recognize
	gvks, _, err := s.ObjectKinds(in)
	if err != nil {
		return nil, err
	}
	typed, err := s.New(gvks[0])
	if err != nil {
		return nil, err
	}
	if err := DefaultUnstructuredConverter.FromUnstructured(in.UnstructuredContent(), typed); err != nil {
		return nil, fmt.Errorf("unable to convert unstructured object to %v: %v", gvks[0], err)
	}
	return typed, nil
}

// generateConvertMeta constructs the meta value we pass to Convert.
func (s *Scheme) generateConvertMeta(in interface{}) (conversion.FieldMatchingFlags, *conversion.Meta) {
	return s.converter.DefaultMeta(reflect.TypeOf(in))
}

// copyAndSetTargetKind performs a conditional copy before returning the object, or an error if copy was not successful.
func copyAndSetTargetKind(copy bool, obj Object, kind schema.GroupVersionKind) (Object, error) {
	if copy {
		obj = obj.DeepCopyObject()
	}
	setTargetKind(obj, kind)
	return obj, nil
}

// setTargetKind sets the kind on an object, taking into account whether the target kind is the internal version.
func setTargetKind(obj Object, kind schema.GroupVersionKind) {
	if kind.Version == APIVersionInternal {
		// internal is a special case
		// TODO: look at removing the need to special case this
		obj.GetObjectKind().SetGroupVersionKind(schema.GroupVersionKind{})
		return
	}
	obj.GetObjectKind().SetGroupVersionKind(kind)
}

// SetVersionPriority allows specifying a precise order of priority. All specified versions must be in the same group,
// and the specified order overwrites any previously specified order for this group
func (s *Scheme) SetVersionPriority(versions ...schema.GroupVersion) error {
	groups := sets.String{}
	order := []string{}
	for _, version := range versions {
		if len(version.Version) == 0 || version.Version == APIVersionInternal {
			return fmt.Errorf("internal versions cannot be prioritized: %v", version)
		}

		groups.Insert(version.Group)
		order = append(order, version.Version)
	}
	if len(groups) != 1 {
		return fmt.Errorf("must register versions for exactly one group: %v", strings.Join(groups.List(), ", "))
	}

	s.versionPriority[groups.List()[0]] = order
	return nil
}

// PrioritizedVersionsForGroup returns versions for a single group in priority order
func (s *Scheme) PrioritizedVersionsForGroup(group string) []schema.GroupVersion {
	ret := []schema.GroupVersion{}
	for _, version := range s.versionPriority[group] {
		ret = append(ret, schema.GroupVersion{Group: group, Version: version})
	}
	for _, observedVersion := range s.observedVersions {
		if observedVersion.Group != group {
			continue
		}
		found := false
		for _, existing := range ret {
			if existing == observedVersion {
				found = true
				break
			}
		}
		if !found {
			ret = append(ret, observedVersion)
		}
	}

	return ret
}

// PrioritizedVersionsAllGroups returns all known versions in their priority order.  Groups are random, but
// versions for a single group are prioritized
func (s *Scheme) PrioritizedVersionsAllGroups() []schema.GroupVersion {
	ret := []schema.GroupVersion{}
	for group, versions := range s.versionPriority {
		for _, version := range versions {
			ret = append(ret, schema.GroupVersion{Group: group, Version: version})
		}
	}
	for _, observedVersion := range s.observedVersions {
		found := false
		for _, existing := range ret {
			if existing == observedVersion {
				found = true
				break
			}
		}
		if !found {
			ret = append(ret, observedVersion)
		}
	}
	return ret
}

// PreferredVersionAllGroups returns the most preferred version for every group.
// group ordering is random.
func (s *Scheme) PreferredVersionAllGroups() []schema.GroupVersion {
	ret := []schema.GroupVersion{}
	for group, versions := range s.versionPriority {
		for _, version := range versions {
			ret = append(ret, schema.GroupVersion{Group: group, Version: version})
			break
		}
	}
	for _, observedVersion := range s.observedVersions {
		found := false
		for _, existing := range ret {
			if existing.Group == observedVersion.Group {
				found = true
				break
			}
		}
		if !found {
			ret = append(ret, observedVersion)
		}
	}

	return ret
}

// IsGroupRegistered returns true if types for the group have been registered with the scheme
func (s *Scheme) IsGroupRegistered(group string) bool {
	for _, observedVersion := range s.observedVersions {
		if observedVersion.Group == group {
			return true
		}
	}
	return false
}

// IsVersionRegistered returns true if types for the version have been registered with the scheme
func (s *Scheme) IsVersionRegistered(version schema.GroupVersion) bool {
	for _, observedVersion := range s.observedVersions {
		if observedVersion == version {
			return true
		}
	}

	return false
}

func (s *Scheme) addObservedVersion(version schema.GroupVersion) {
	if len(version.Version) == 0 || version.Version == APIVersionInternal {
		return
	}
	for _, observedVersion := range s.observedVersions {
		if observedVersion == version {
			return
		}
	}

	s.observedVersions = append(s.observedVersions, version)
}

func (s *Scheme) Name() string {
	return s.schemeName
}

// internalPackages are packages that ignored when creating a default reflector name. These packages are in the common
// call chains to NewReflector, so they'd be low entropy names for reflectors
var internalPackages = []string{"k8s.io/apimachinery/pkg/runtime/scheme.go"}