Merge pull request #1532 from monopole/runBuiltinSansFlag

Ease configuring and running the builtin plugins.

cmd/pluginator/main.go

@@ -16,6 +16,15 @@ import (
 	"sigs.k8s.io/kustomize/v3/pkg/plugins"
 )
 
+//go:generate stringer -type=pluginType
+type pluginType int
+
+const (
+	unknown pluginType = iota
+	Transformer
+	Generator
+)
+
 func main() {
 	root := inputFileRoot()
 	file, err := os.Open(root + ".go")
@@ -34,24 +43,41 @@ func main() {
 		fmt.Sprintf(
 			"// Code generated by pluginator on %s; DO NOT EDIT.",
 			root))
-	w.write("package builtin")
+	w.write("package " + plugins.BuiltinPluginPackage)
+
+	pType := unknown
 
 	for scanner.Scan() {
 		l := scanner.Text()
 		if strings.HasPrefix(l, "//go:generate") {
 			continue
 		}
-		if l == "var "+plugins.PluginSymbol+" plugin" {
-			w.write("func New" + root + "Plugin() *" + root + "Plugin {")
-			w.write("  return &" + root + "Plugin{}")
-			w.write("}")
+		if strings.HasPrefix(l, "//noinspection") {
 			continue
 		}
+		if l == "var "+plugins.PluginSymbol+" plugin" {
+			continue
+		}
+		if strings.Contains(l, " Transform(") {
+			if pType != unknown {
+				log.Fatal("unexpected Transform(")
+			}
+			pType = Transformer
+		} else if strings.Contains(l, " Generate(") {
+			if pType != unknown {
+				log.Fatal("unexpected Generate(")
+			}
+			pType = Generator
+		}
 		w.write(l)
 	}
 	if err := scanner.Err(); err != nil {
 		log.Fatal(err)
 	}
+	w.write("")
+	w.write("func New" + root + "Plugin() resmap." + pType.String() + "Plugin {")
+	w.write("  return &" + root + "Plugin{}")
+	w.write("}")
 }
 
 func inputFileRoot() string {
@@ -93,7 +119,7 @@ func makeOutputFileName(root string) string {
 		pgmconfig.DomainName,
 		pgmconfig.ProgramName,
 		pgmconfig.PluginRoot,
-		"builtin",
+		plugins.BuiltinPluginPackage,
 		root+".go")
 }
 

cmd/pluginator/plugintype_string.go

@@ -0,0 +1,25 @@
+// Code generated by "stringer -type=pluginType"; DO NOT EDIT.
+
+package main
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[unknown-0]
+	_ = x[Transformer-1]
+	_ = x[Generator-2]
+}
+
+const _pluginType_name = "unknownTransformerGenerator"
+
+var _pluginType_index = [...]uint8{0, 7, 18, 27}
+
+func (i pluginType) String() string {
+	if i < 0 || i >= pluginType(len(_pluginType_index)-1) {
+		return "pluginType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _pluginType_name[_pluginType_index[i]:_pluginType_index[i+1]]
+}

pkg/accumulator/resaccumulator.go

@@ -135,7 +135,7 @@ func (ra *ResAccumulator) makeVarReplacementMap() (map[string]interface{}, error
 	return result, nil
 }
 
-func (ra *ResAccumulator) Transform(t transformers.Transformer) error {
+func (ra *ResAccumulator) Transform(t resmap.Transformer) error {
 	return t.Transform(ra.resMap)
 }
 

pkg/plugins/builtinplugintype_string.go

@@ -0,0 +1,37 @@
+// Code generated by "stringer -type=BuiltinPluginType"; DO NOT EDIT.
+
+package plugins
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Unknown-0]
+	_ = x[SecretGenerator-1]
+	_ = x[ConfigMapGenerator-2]
+	_ = x[ReplicaCountTransformer-3]
+	_ = x[NamespaceTransformer-4]
+	_ = x[PatchJson6902Transformer-5]
+	_ = x[PatchStrategicMergeTransformer-6]
+	_ = x[PatchTransformer-7]
+	_ = x[LabelTransformer-8]
+	_ = x[AnnotationsTransformer-9]
+	_ = x[PrefixSuffixTransformer-10]
+	_ = x[ImageTagTransformer-11]
+	_ = x[HashTransformer-12]
+	_ = x[InventoryTransformer-13]
+	_ = x[LegacyOrderTransformer-14]
+}
+
+const _BuiltinPluginType_name = "UnknownSecretGeneratorConfigMapGeneratorReplicaCountTransformerNamespaceTransformerPatchJson6902TransformerPatchStrategicMergeTransformerPatchTransformerLabelTransformerAnnotationsTransformerPrefixSuffixTransformerImageTagTransformerHashTransformerInventoryTransformerLegacyOrderTransformer"
+
+var _BuiltinPluginType_index = [...]uint16{0, 7, 22, 40, 63, 83, 107, 137, 153, 169, 191, 214, 233, 248, 268, 290}
+
+func (i BuiltinPluginType) String() string {
+	if i < 0 || i >= BuiltinPluginType(len(_BuiltinPluginType_index)-1) {
+		return "BuiltinPluginType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _BuiltinPluginType_name[_BuiltinPluginType_index[i]:_BuiltinPluginType_index[i+1]]
+}

pkg/plugins/builtins.go

@@ -0,0 +1,75 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package plugins
+
+import (
+	"sigs.k8s.io/kustomize/v3/pkg/resmap"
+	"sigs.k8s.io/kustomize/v3/plugin/builtin"
+)
+
+//go:generate stringer -type=BuiltinPluginType
+type BuiltinPluginType int
+
+const (
+	Unknown BuiltinPluginType = iota
+	SecretGenerator
+	ConfigMapGenerator
+	ReplicaCountTransformer
+	NamespaceTransformer
+	PatchJson6902Transformer
+	PatchStrategicMergeTransformer
+	PatchTransformer
+	LabelTransformer
+	AnnotationsTransformer
+	PrefixSuffixTransformer
+	ImageTagTransformer
+	HashTransformer
+	InventoryTransformer
+	LegacyOrderTransformer
+)
+
+var stringToBuiltinPluginTypeMap map[string]BuiltinPluginType
+
+func init() {
+	stringToBuiltinPluginTypeMap = makeStringToBuiltinPluginTypeMap()
+}
+
+func makeStringToBuiltinPluginTypeMap() (result map[string]BuiltinPluginType) {
+	result = make(map[string]BuiltinPluginType, 23)
+	for k := range GeneratorFactories {
+		result[k.String()] = k
+	}
+	for k := range TransformerFactories {
+		result[k.String()] = k
+	}
+	return
+}
+
+func GetBuiltinPluginType(n string) BuiltinPluginType {
+	result, ok := stringToBuiltinPluginTypeMap[n]
+	if ok {
+		return result
+	}
+	return Unknown
+}
+
+var GeneratorFactories = map[BuiltinPluginType]func() resmap.GeneratorPlugin{
+	SecretGenerator:    builtin.NewSecretGeneratorPlugin,
+	ConfigMapGenerator: builtin.NewConfigMapGeneratorPlugin,
+}
+
+var TransformerFactories = map[BuiltinPluginType]func() resmap.TransformerPlugin{
+	NamespaceTransformer:           builtin.NewNamespaceTransformerPlugin,
+	ReplicaCountTransformer:        builtin.NewReplicaCountTransformerPlugin,
+	PatchJson6902Transformer:       builtin.NewPatchJson6902TransformerPlugin,
+	PatchStrategicMergeTransformer: builtin.NewPatchStrategicMergeTransformerPlugin,
+	PatchTransformer:               builtin.NewPatchTransformerPlugin,
+	LabelTransformer:               builtin.NewLabelTransformerPlugin,
+	AnnotationsTransformer:         builtin.NewAnnotationsTransformerPlugin,
+	PrefixSuffixTransformer:        builtin.NewPrefixSuffixTransformerPlugin,
+	ImageTagTransformer:            builtin.NewImageTagTransformerPlugin,
+	HashTransformer:                builtin.NewHashTransformerPlugin,
+	InventoryTransformer:           builtin.NewInventoryTransformerPlugin,
+	LegacyOrderTransformer:         builtin.NewLegacyOrderTransformerPlugin,
+}

pkg/plugins/config.go

@@ -12,13 +12,15 @@ import (
 )
 
 const (
-	PluginSymbol          = "KustomizePlugin"
-	flagEnablePluginsName = "enable_alpha_plugins"
-	flagEnablePluginsHelp = `enable plugins, an alpha feature.
+	PluginSymbol            = "KustomizePlugin"
+	BuiltinPluginPackage    = "builtin"
+	BuiltinPluginApiVersion = BuiltinPluginPackage
+	flagEnablePluginsName   = "enable_alpha_plugins"
+	flagEnablePluginsHelp   = `enable plugins, an alpha feature.
 See https://github.com/kubernetes-sigs/kustomize/blob/master/docs/plugins.md
 `
 	flagErrorFmt = `
-unable to load plugin %s because plugins disabled
+unable to load external plugin %s because plugins disabled
 specify the flag
   --%s
 to %s`

pkg/plugins/loader.go

@@ -11,18 +11,14 @@ import (
 	"strings"
 
 	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/v3/pkg/gvk"
 	"sigs.k8s.io/kustomize/v3/pkg/ifc"
 	"sigs.k8s.io/kustomize/v3/pkg/resid"
 	"sigs.k8s.io/kustomize/v3/pkg/resmap"
 	"sigs.k8s.io/kustomize/v3/pkg/resource"
-	"sigs.k8s.io/kustomize/v3/pkg/transformers"
 	"sigs.k8s.io/kustomize/v3/pkg/types"
 )
 
-type Configurable interface {
-	Config(ldr ifc.Loader, rf *resmap.Factory, config []byte) error
-}
-
 type Loader struct {
 	pc *types.PluginConfig
 	rf *resmap.Factory
@@ -34,8 +30,8 @@ func NewLoader(
 }
 
 func (l *Loader) LoadGenerators(
-	ldr ifc.Loader, rm resmap.ResMap) ([]transformers.Generator, error) {
-	var result []transformers.Generator
+	ldr ifc.Loader, rm resmap.ResMap) ([]resmap.Generator, error) {
+	var result []resmap.Generator
 	for _, res := range rm.Resources() {
 		g, err := l.LoadGenerator(ldr, res)
 		if err != nil {
@@ -47,12 +43,12 @@ func (l *Loader) LoadGenerators(
 }
 
 func (l *Loader) LoadGenerator(
-	ldr ifc.Loader, res *resource.Resource) (transformers.Generator, error) {
+	ldr ifc.Loader, res *resource.Resource) (resmap.Generator, error) {
 	c, err := l.loadAndConfigurePlugin(ldr, res)
 	if err != nil {
 		return nil, err
 	}
-	g, ok := c.(transformers.Generator)
+	g, ok := c.(resmap.Generator)
 	if !ok {
 		return nil, fmt.Errorf("plugin %s not a generator", res.OrgId())
 	}
@@ -60,8 +56,8 @@ func (l *Loader) LoadGenerator(
 }
 
 func (l *Loader) LoadTransformers(
-	ldr ifc.Loader, rm resmap.ResMap) ([]transformers.Transformer, error) {
-	var result []transformers.Transformer
+	ldr ifc.Loader, rm resmap.ResMap) ([]resmap.Transformer, error) {
+	var result []resmap.Transformer
 	for _, res := range rm.Resources() {
 		t, err := l.LoadTransformer(ldr, res)
 		if err != nil {
@@ -73,12 +69,12 @@ func (l *Loader) LoadTransformers(
 }
 
 func (l *Loader) LoadTransformer(
-	ldr ifc.Loader, res *resource.Resource) (transformers.Transformer, error) {
+	ldr ifc.Loader, res *resource.Resource) (resmap.Transformer, error) {
 	c, err := l.loadAndConfigurePlugin(ldr, res)
 	if err != nil {
 		return nil, err
 	}
-	t, ok := c.(transformers.Transformer)
+	t, ok := c.(resmap.Transformer)
 	if !ok {
 		return nil, fmt.Errorf("plugin %s not a transformer", res.OrgId())
 	}
@@ -101,13 +97,25 @@ func (l *Loader) absolutePluginPath(id resid.ResId) string {
 	return AbsolutePluginPath(l.pc, id)
 }
 
-// TODO: https://github.com/kubernetes-sigs/kustomize/issues/1164
+func isBuiltinPlugin(res *resource.Resource) bool {
+	// TODO: the special string should appear in Group, not Version.
+	return res.GetGvk().Group == "" &&
+		res.GetGvk().Version == BuiltinPluginApiVersion
+}
+
 func (l *Loader) loadAndConfigurePlugin(
-	ldr ifc.Loader, res *resource.Resource) (Configurable, error) {
-	if !l.pc.Enabled {
-		return nil, NotEnabledErr(res.OrgId().Kind)
+	ldr ifc.Loader, res *resource.Resource) (c resmap.Configurable, err error) {
+	if isBuiltinPlugin(res) {
+		// Instead of looking for and loading a .so file, just
+		// instantiate the plugin from a generated factory
+		// function (see "pluginator").  Being able to do this
+		// is what makes a plugin "builtin".
+		c, err = l.makeBuiltinPlugin(res.GetGvk())
+	} else if l.pc.Enabled {
+		c, err = l.loadPlugin(res.OrgId())
+	} else {
+		err = NotEnabledErr(res.OrgId().Kind)
 	}
-	c, err := l.loadPlugin(res.OrgId())
 	if err != nil {
 		return nil, err
 	}
@@ -123,7 +131,18 @@ func (l *Loader) loadAndConfigurePlugin(
 	return c, nil
 }
 
-func (l *Loader) loadPlugin(resId resid.ResId) (Configurable, error) {
+func (l *Loader) makeBuiltinPlugin(r gvk.Gvk) (resmap.Configurable, error) {
+	bpt := GetBuiltinPluginType(r.Kind)
+	if f, ok := GeneratorFactories[bpt]; ok {
+		return f(), nil
+	}
+	if f, ok := TransformerFactories[bpt]; ok {
+		return f(), nil
+	}
+	return nil, errors.Errorf("unable to load builtin %s", r)
+}
+
+func (l *Loader) loadPlugin(resId resid.ResId) (resmap.Configurable, error) {
 	p := NewExecPlugin(l.absolutePluginPath(resId))
 	if p.isAvailable() {
 		return p, nil
@@ -141,9 +160,9 @@ func (l *Loader) loadPlugin(resId resid.ResId) (Configurable, error) {
 // but the loaded .so files are in shared memory, so one will get
 // "this plugin already loaded" errors if the registry is maintained
 // as a Loader instance variable.  So make it a package variable.
-var registry = make(map[string]Configurable)
+var registry = make(map[string]resmap.Configurable)
 
-func (l *Loader) loadGoPlugin(id resid.ResId) (Configurable, error) {
+func (l *Loader) loadGoPlugin(id resid.ResId) (resmap.Configurable, error) {
 	regId := relativePluginPath(id)
 	if c, ok := registry[regId]; ok {
 		return copyPlugin(c), nil
@@ -159,7 +178,7 @@ func (l *Loader) loadGoPlugin(id resid.ResId) (Configurable, error) {
 			err, "plugin %s doesn't have symbol %s",
 			regId, PluginSymbol)
 	}
-	c, ok := symbol.(Configurable)
+	c, ok := symbol.(resmap.Configurable)
 	if !ok {
 		return nil, fmt.Errorf("plugin %s not configurable", regId)
 	}
@@ -167,10 +186,10 @@ func (l *Loader) loadGoPlugin(id resid.ResId) (Configurable, error) {
 	return copyPlugin(c), nil
 }
 
-func copyPlugin(c Configurable) Configurable {
+func copyPlugin(c resmap.Configurable) resmap.Configurable {
 	indirect := reflect.Indirect(reflect.ValueOf(c))
 	newIndirect := reflect.New(indirect.Type())
 	newIndirect.Elem().Set(reflect.ValueOf(indirect.Interface()))
 	newNamed := newIndirect.Interface()
-	return newNamed.(Configurable)
+	return newNamed.(resmap.Configurable)
 }

pkg/resmap/resmap.go

@@ -11,13 +11,45 @@ import (
 	"regexp"
 
 	"github.com/pkg/errors"
-
+	"sigs.k8s.io/kustomize/v3/pkg/ifc"
 	"sigs.k8s.io/kustomize/v3/pkg/resid"
 	"sigs.k8s.io/kustomize/v3/pkg/resource"
 	"sigs.k8s.io/kustomize/v3/pkg/types"
 	"sigs.k8s.io/yaml"
 )
 
+// A Transformer modifies an instance of ResMap.
+type Transformer interface {
+	// Transform modifies data in the argument,
+	// e.g. adding labels to resources that can be labelled.
+	Transform(m ResMap) error
+}
+
+// A Generator creates an instance of ResMap.
+type Generator interface {
+	Generate() (ResMap, error)
+}
+
+// Something that's configurable accepts a config
+// object (typically YAML in []byte form), and an
+// ifc.Loader to possible read more configuration
+// from the file system (e.g. patch files) and
+// a resource factory to build any type-sensitive
+// parts.  The factory could probably be factored out.
+type Configurable interface {
+	Config(ldr ifc.Loader, rf *Factory, config []byte) error
+}
+
+type GeneratorPlugin interface {
+	Generator
+	Configurable
+}
+
+type TransformerPlugin interface {
+	Transformer
+	Configurable
+}
+
 // ResMap is an interface describing operations on the
 // core kustomize data structure, a list of Resources.
 //

pkg/target/kusttarget.go

@@ -160,7 +160,7 @@ func (kt *KustTarget) makeCustomizedResMap(
 func (kt *KustTarget) addHashesToNames(
 	ra *accumulator.ResAccumulator) error {
 	p := builtin.NewHashTransformerPlugin()
-	err := kt.configureBuiltinPlugin(p, nil, "hash")
+	err := kt.configureBuiltinPlugin(p, nil, plugins.HashTransformer)
 	if err != nil {
 		return err
 	}
@@ -181,7 +181,6 @@ func (kt *KustTarget) computeInventory(
 		return fmt.Errorf("namespace mismatch")
 	}
 
-	p := builtin.NewInventoryTransformerPlugin()
 	var c struct {
 		Policy           string
 		types.ObjectMeta `json:"metadata,omitempty" yaml:"metadata,omitempty"`
@@ -189,8 +188,8 @@ func (kt *KustTarget) computeInventory(
 	c.Name = inv.ConfigMap.Name
 	c.Namespace = inv.ConfigMap.Namespace
 	c.Policy = garbagePolicy.String()
-
-	err := kt.configureBuiltinPlugin(p, c, "inventory")
+	p := builtin.NewInventoryTransformerPlugin()
+	err := kt.configureBuiltinPlugin(p, c, plugins.InventoryTransformer)
 	if err != nil {
 		return err
 	}
@@ -283,7 +282,7 @@ func (kt *KustTarget) runGenerators(
 	return nil
 }
 
-func (kt *KustTarget) configureExternalGenerators() ([]transformers.Generator, error) {
+func (kt *KustTarget) configureExternalGenerators() ([]resmap.Generator, error) {
 	ra := accumulator.MakeEmptyAccumulator()
 	err := kt.accumulateResources(ra, kt.kustomization.Generators)
 	if err != nil {
@@ -293,7 +292,7 @@ func (kt *KustTarget) configureExternalGenerators() ([]transformers.Generator, e
 }
 
 func (kt *KustTarget) runTransformers(ra *accumulator.ResAccumulator) error {
-	var r []transformers.Transformer
+	var r []resmap.Transformer
 	tConfig := ra.GetTransformerConfig()
 	lts, err := kt.configureBuiltinTransformers(tConfig)
 	if err != nil {
@@ -309,7 +308,7 @@ func (kt *KustTarget) runTransformers(ra *accumulator.ResAccumulator) error {
 	return ra.Transform(t)
 }
 
-func (kt *KustTarget) configureExternalTransformers() ([]transformers.Transformer, error) {
+func (kt *KustTarget) configureExternalTransformers() ([]resmap.Transformer, error) {
 	ra := accumulator.MakeEmptyAccumulator()
 	err := kt.accumulateResources(ra, kt.kustomization.Transformers)
 	if err != nil {
@@ -374,3 +373,20 @@ func (kt *KustTarget) accumulateFile(
 	}
 	return nil
 }
+
+func (kt *KustTarget) configureBuiltinPlugin(
+	p resmap.Configurable, c interface{}, bpt plugins.BuiltinPluginType) (err error) {
+	var y []byte
+	if c != nil {
+		y, err = yaml.Marshal(c)
+		if err != nil {
+			return errors.Wrapf(
+				err, "builtin %s marshal", bpt)
+		}
+	}
+	err = p.Config(kt.ldr, kt.rFactory, y)
+	if err != nil {
+		return errors.Wrapf(err, "builtin %s config: %v", bpt, y)
+	}
+	return nil
+}

pkg/target/kusttarget_configplugin.go

@@ -4,50 +4,36 @@
 package target
 
 import (
-	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/v3/pkg/image"
 	"sigs.k8s.io/kustomize/v3/pkg/plugins"
-	"sigs.k8s.io/kustomize/v3/pkg/transformers"
+	"sigs.k8s.io/kustomize/v3/pkg/resmap"
 	"sigs.k8s.io/kustomize/v3/pkg/transformers/config"
 	"sigs.k8s.io/kustomize/v3/pkg/types"
-	"sigs.k8s.io/kustomize/v3/plugin/builtin"
-	"sigs.k8s.io/yaml"
 )
 
 // Functions dedicated to configuring the builtin
 // transformer and generator plugins using config data
-// read from a kustomization file.
+// read from a kustomization file and from the
+// config.TransformerConfig, whose data may be a
+// mix of hardcoded values and data read from file.
 //
 // Non-builtin plugins will get their configuration
-// from their own dedicated structs and yaml files.
+// from their own dedicated structs and YAML files.
 //
 // There are some loops in the functions below because
-// the kustomization file would, say, allow one to
+// the kustomization file would, say, allow someone to
 // request multiple secrets be made, or run multiple
-// image tag transforms, so we need to run the plugins
-// N times (plugins are easier to write, configure and
-// test if they do just one thing).
-//
-// TODO: Push code down into the plugins, as the first pass
-//     at this writes plugins as thin layers over calls
-//     into existing packages.  The builtin plugins should
-//     be viewed as examples, and the packages they access
-//     directory should be public, while everything else
-//     should go into internal.
-
-type generatorConfigurator func() ([]transformers.Generator, error)
-type transformerConfigurator func(
-	tConfig *config.TransformerConfig) ([]transformers.Transformer, error)
+// image tag transforms.  In these cases, we'll need
+// N plugin instances with differing configurations.
 
 func (kt *KustTarget) configureBuiltinGenerators() (
-	[]transformers.Generator, error) {
-	configurators := []generatorConfigurator{
-		kt.configureBuiltinConfigMapGenerator,
-		kt.configureBuiltinSecretGenerator,
-	}
-	var result []transformers.Generator
-	for _, f := range configurators {
-		r, err := f()
+	result []resmap.Generator, err error) {
+	for _, bpt := range []plugins.BuiltinPluginType{
+		plugins.ConfigMapGenerator,
+		plugins.SecretGenerator,
+	} {
+		r, err := generatorConfigurators[bpt](
+			kt, bpt, plugins.GeneratorFactories[bpt])
 		if err != nil {
 			return nil, err
 		}
@@ -57,270 +43,256 @@ func (kt *KustTarget) configureBuiltinGenerators() (
 }
 
 func (kt *KustTarget) configureBuiltinTransformers(
-	tConfig *config.TransformerConfig) (
-	[]transformers.Transformer, error) {
-	// TODO: Convert remaining legacy transformers to plugins
-	//   with tests:
-	//   - patch SMP
-	configurators := []transformerConfigurator{
-		kt.configureBuiltinPatchStrategicMergeTransformer,
-		kt.configureBuiltinPatchTransformer,
-		kt.configureBuiltinNamespaceTransformer,
-		kt.configureBuiltinNameTransformer,
-		kt.configureBuiltinLabelTransformer,
-		kt.configureBuiltinAnnotationsTransformer,
-		kt.configureBuiltinPatchJson6902Transformer,
-		kt.configureBuiltinReplicaCountTransformer,
-		kt.configureBuiltinImageTagTransformer,
-	}
-	var result []transformers.Transformer
-	for _, f := range configurators {
-		r, err := f(tConfig)
+	tc *config.TransformerConfig) (
+	result []resmap.Transformer, err error) {
+	for _, bpt := range []plugins.BuiltinPluginType{
+		plugins.PatchStrategicMergeTransformer,
+		plugins.PatchTransformer,
+		plugins.NamespaceTransformer,
+		plugins.PrefixSuffixTransformer,
+		plugins.LabelTransformer,
+		plugins.AnnotationsTransformer,
+		plugins.PatchJson6902Transformer,
+		plugins.ReplicaCountTransformer,
+		plugins.ImageTagTransformer,
+	} {
+		r, err := transformerConfigurators[bpt](
+			kt, bpt, plugins.TransformerFactories[bpt], tc)
 		if err != nil {
 			return nil, err
 		}
 		result = append(result, r...)
 	}
-
 	return result, nil
 }
 
-func (kt *KustTarget) configureBuiltinSecretGenerator() (
-	result []transformers.Generator, err error) {
-	var c struct {
-		types.GeneratorOptions
-		types.SecretArgs
-	}
-	if kt.kustomization.GeneratorOptions != nil {
-		c.GeneratorOptions = *kt.kustomization.GeneratorOptions
-	}
-	for _, args := range kt.kustomization.SecretGenerator {
-		c.SecretArgs = args
-		p := builtin.NewSecretGeneratorPlugin()
-		err = kt.configureBuiltinPlugin(p, c, "secret")
-		if err != nil {
-			return nil, err
+type gFactory func() resmap.GeneratorPlugin
+
+var generatorConfigurators = map[plugins.BuiltinPluginType]func(
+	kt *KustTarget,
+	bpt plugins.BuiltinPluginType,
+	factory gFactory) (result []resmap.Generator, err error){
+	plugins.SecretGenerator: func(kt *KustTarget, bpt plugins.BuiltinPluginType, f gFactory) (
+		result []resmap.Generator, err error) {
+		var c struct {
+			types.GeneratorOptions
+			types.SecretArgs
 		}
-		result = append(result, p)
-	}
-	return
-}
-
-func (kt *KustTarget) configureBuiltinConfigMapGenerator() (
-	result []transformers.Generator, err error) {
-	var c struct {
-		types.GeneratorOptions
-		types.ConfigMapArgs
-	}
-	if kt.kustomization.GeneratorOptions != nil {
-		c.GeneratorOptions = *kt.kustomization.GeneratorOptions
-	}
-	for _, args := range kt.kustomization.ConfigMapGenerator {
-		c.ConfigMapArgs = args
-		p := builtin.NewConfigMapGeneratorPlugin()
-		err = kt.configureBuiltinPlugin(p, c, "configmap")
-		if err != nil {
-			return nil, err
+		if kt.kustomization.GeneratorOptions != nil {
+			c.GeneratorOptions = *kt.kustomization.GeneratorOptions
 		}
-		result = append(result, p)
-	}
-	return
-}
-
-func (kt *KustTarget) configureBuiltinNamespaceTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		types.ObjectMeta `json:"metadata,omitempty" yaml:"metadata,omitempty"`
-		FieldSpecs       []config.FieldSpec
-	}
-	c.Namespace = kt.kustomization.Namespace
-	c.FieldSpecs = tConfig.NameSpace
-	p := builtin.NewNamespaceTransformerPlugin()
-	err = kt.configureBuiltinPlugin(p, c, "namespace")
-	if err != nil {
-		return nil, err
-	}
-	result = append(result, p)
-	return
-}
-
-func (kt *KustTarget) configureBuiltinPatchJson6902Transformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		Target types.PatchTarget `json:"target,omitempty" yaml:"target,omitempty"`
-		Path   string            `json:"path,omitempty" yaml:"path,omitempty"`
-		JsonOp string            `json:"jsonOp,omitempty" yaml:"jsonOp,omitempty"`
-	}
-	for _, args := range kt.kustomization.PatchesJson6902 {
-		c.Target = *args.Target
-		c.Path = args.Path
-		c.JsonOp = args.Patch
-		p := builtin.NewPatchJson6902TransformerPlugin()
-		err = kt.configureBuiltinPlugin(p, c, "patchJson6902")
-		if err != nil {
-			return nil, err
+		for _, args := range kt.kustomization.SecretGenerator {
+			c.SecretArgs = args
+			p := f()
+			err := kt.configureBuiltinPlugin(p, c, bpt)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, p)
 		}
-		result = append(result, p)
-	}
-	return
-}
-
-func (kt *KustTarget) configureBuiltinPatchStrategicMergeTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	if len(kt.kustomization.PatchesStrategicMerge) == 0 {
 		return
-	}
-	var c struct {
-		Paths   []types.PatchStrategicMerge `json:"paths,omitempty" yaml:"paths,omitempty"`
-		Patches string                      `json:"patches,omitempty" yaml:"patches,omitempty"`
-	}
-	c.Paths = kt.kustomization.PatchesStrategicMerge
-	p := builtin.NewPatchStrategicMergeTransformerPlugin()
-	err = kt.configureBuiltinPlugin(p, c, "patchStrategicMerge")
-	if err != nil {
-		return nil, err
-	}
-	result = append(result, p)
-	return
-}
+	},
 
-func (kt *KustTarget) configureBuiltinPatchTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	if len(kt.kustomization.Patches) == 0 {
+	plugins.ConfigMapGenerator: func(kt *KustTarget, bpt plugins.BuiltinPluginType, f gFactory) (
+		result []resmap.Generator, err error) {
+		var c struct {
+			types.GeneratorOptions
+			types.ConfigMapArgs
+		}
+		if kt.kustomization.GeneratorOptions != nil {
+			c.GeneratorOptions = *kt.kustomization.GeneratorOptions
+		}
+		for _, args := range kt.kustomization.ConfigMapGenerator {
+			c.ConfigMapArgs = args
+			p := f()
+			err := kt.configureBuiltinPlugin(p, c, bpt)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, p)
+		}
 		return
-	}
-	var c struct {
-		Path   string          `json:"path,omitempty" yaml:"path,omitempty"`
-		Patch  string          `json:"patch,omitempty" yaml:"patch,omitempty"`
-		Target *types.Selector `json:"target,omitempty" yaml:"target,omitempty"`
-	}
-	for _, patch := range kt.kustomization.Patches {
-		c.Target = patch.Target
-		c.Patch = patch.Patch
-		c.Path = patch.Path
-		p := builtin.NewPatchTransformerPlugin()
-		err = kt.configureBuiltinPlugin(p, c, "patch")
+	},
+}
+
+type tFactory func() resmap.TransformerPlugin
+
+var transformerConfigurators = map[plugins.BuiltinPluginType]func(
+	kt *KustTarget,
+	bpt plugins.BuiltinPluginType,
+	f tFactory,
+	tc *config.TransformerConfig) (result []resmap.Transformer, err error){
+	plugins.NamespaceTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, tc *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			types.ObjectMeta `json:"metadata,omitempty" yaml:"metadata,omitempty"`
+			FieldSpecs       []config.FieldSpec
+		}
+		c.Namespace = kt.kustomization.Namespace
+		c.FieldSpecs = tc.NameSpace
+		p := f()
+		err = kt.configureBuiltinPlugin(p, c, bpt)
 		if err != nil {
 			return nil, err
 		}
 		result = append(result, p)
-	}
-	return
-}
+		return
+	},
 
-func (kt *KustTarget) configureBuiltinLabelTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		Labels     map[string]string
-		FieldSpecs []config.FieldSpec
-	}
-	c.Labels = kt.kustomization.CommonLabels
-	c.FieldSpecs = tConfig.CommonLabels
-	p := builtin.NewLabelTransformerPlugin()
-	err = kt.configureBuiltinPlugin(p, c, "label")
-	if err != nil {
-		return nil, err
-	}
-	result = append(result, p)
-	return
-}
-
-func (kt *KustTarget) configureBuiltinAnnotationsTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		Annotations map[string]string
-		FieldSpecs  []config.FieldSpec
-	}
-	c.Annotations = kt.kustomization.CommonAnnotations
-	c.FieldSpecs = tConfig.CommonAnnotations
-	p := builtin.NewAnnotationsTransformerPlugin()
-	err = kt.configureBuiltinPlugin(p, c, "annotations")
-	if err != nil {
-		return nil, err
-	}
-	result = append(result, p)
-	return
-}
-
-func (kt *KustTarget) configureBuiltinNameTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		Prefix     string
-		Suffix     string
-		FieldSpecs []config.FieldSpec
-	}
-	c.Prefix = kt.kustomization.NamePrefix
-	c.Suffix = kt.kustomization.NameSuffix
-	c.FieldSpecs = tConfig.NamePrefix
-	p := builtin.NewPrefixSuffixTransformerPlugin()
-	err = kt.configureBuiltinPlugin(p, c, "prefixsuffix")
-	if err != nil {
-		return nil, err
-	}
-	result = append(result, p)
-	return
-}
-
-func (kt *KustTarget) configureBuiltinImageTagTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		ImageTag   image.Image
-		FieldSpecs []config.FieldSpec
-	}
-	for _, args := range kt.kustomization.Images {
-		c.ImageTag = args
-		c.FieldSpecs = tConfig.Images
-		p := builtin.NewImageTagTransformerPlugin()
-		err = kt.configureBuiltinPlugin(p, c, "imageTag")
+	plugins.PatchJson6902Transformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, _ *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			Target types.PatchTarget `json:"target,omitempty" yaml:"target,omitempty"`
+			Path   string            `json:"path,omitempty" yaml:"path,omitempty"`
+			JsonOp string            `json:"jsonOp,omitempty" yaml:"jsonOp,omitempty"`
+		}
+		for _, args := range kt.kustomization.PatchesJson6902 {
+			c.Target = *args.Target
+			c.Path = args.Path
+			c.JsonOp = args.Patch
+			p := f()
+			err = kt.configureBuiltinPlugin(p, c, bpt)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, p)
+		}
+		return
+	},
+	plugins.PatchStrategicMergeTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, _ *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		if len(kt.kustomization.PatchesStrategicMerge) == 0 {
+			return
+		}
+		var c struct {
+			Paths   []types.PatchStrategicMerge `json:"paths,omitempty" yaml:"paths,omitempty"`
+			Patches string                      `json:"patches,omitempty" yaml:"patches,omitempty"`
+		}
+		c.Paths = kt.kustomization.PatchesStrategicMerge
+		p := f()
+		err = kt.configureBuiltinPlugin(p, c, bpt)
 		if err != nil {
 			return nil, err
 		}
 		result = append(result, p)
-	}
-	return
-}
-
-func (kt *KustTarget) configureBuiltinReplicaCountTransformer(
-	tConfig *config.TransformerConfig) (
-	result []transformers.Transformer, err error) {
-	var c struct {
-		Replica    types.Replica
-		FieldSpecs []config.FieldSpec
-	}
-	for _, args := range kt.kustomization.Replicas {
-		c.Replica = args
-		c.FieldSpecs = tConfig.Replicas
-		p := builtin.NewReplicaCountTransformerPlugin()
-		err = kt.configureBuiltinPlugin(p, c, "replica")
+		return
+	},
+	plugins.PatchTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, _ *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		if len(kt.kustomization.Patches) == 0 {
+			return
+		}
+		var c struct {
+			Path   string          `json:"path,omitempty" yaml:"path,omitempty"`
+			Patch  string          `json:"patch,omitempty" yaml:"patch,omitempty"`
+			Target *types.Selector `json:"target,omitempty" yaml:"target,omitempty"`
+		}
+		for _, pc := range kt.kustomization.Patches {
+			c.Target = pc.Target
+			c.Patch = pc.Patch
+			c.Path = pc.Path
+			p := f()
+			err = kt.configureBuiltinPlugin(p, c, bpt)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, p)
+		}
+		return
+	},
+	plugins.LabelTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, tc *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			Labels     map[string]string
+			FieldSpecs []config.FieldSpec
+		}
+		c.Labels = kt.kustomization.CommonLabels
+		c.FieldSpecs = tc.CommonLabels
+		p := f()
+		err = kt.configureBuiltinPlugin(p, c, bpt)
 		if err != nil {
 			return nil, err
 		}
 		result = append(result, p)
-	}
-	return
-}
-
-func (kt *KustTarget) configureBuiltinPlugin(
-	p plugins.Configurable, c interface{}, id string) (err error) {
-	var y []byte
-	if c != nil {
-		y, err = yaml.Marshal(c)
-		if err != nil {
-			return errors.Wrapf(
-				err, "builtin %s marshal", id)
+		return
+	},
+	plugins.AnnotationsTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, tc *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			Annotations map[string]string
+			FieldSpecs  []config.FieldSpec
 		}
-	}
-	err = p.Config(kt.ldr, kt.rFactory, y)
-	if err != nil {
-		return errors.Wrapf(err, "builtin %s config: %v", id, y)
-	}
-	return nil
+		c.Annotations = kt.kustomization.CommonAnnotations
+		c.FieldSpecs = tc.CommonAnnotations
+		p := f()
+		err = kt.configureBuiltinPlugin(p, c, bpt)
+		if err != nil {
+			return nil, err
+		}
+		result = append(result, p)
+		return
+	},
+	plugins.PrefixSuffixTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, tc *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			Prefix     string
+			Suffix     string
+			FieldSpecs []config.FieldSpec
+		}
+		c.Prefix = kt.kustomization.NamePrefix
+		c.Suffix = kt.kustomization.NameSuffix
+		c.FieldSpecs = tc.NamePrefix
+		p := f()
+		err = kt.configureBuiltinPlugin(p, c, bpt)
+		if err != nil {
+			return nil, err
+		}
+		result = append(result, p)
+		return
+	},
+	plugins.ImageTagTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, tc *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			ImageTag   image.Image
+			FieldSpecs []config.FieldSpec
+		}
+		for _, args := range kt.kustomization.Images {
+			c.ImageTag = args
+			c.FieldSpecs = tc.Images
+			p := f()
+			err = kt.configureBuiltinPlugin(p, c, bpt)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, p)
+		}
+		return
+	},
+	plugins.ReplicaCountTransformer: func(
+		kt *KustTarget, bpt plugins.BuiltinPluginType, f tFactory, tc *config.TransformerConfig) (
+		result []resmap.Transformer, err error) {
+		var c struct {
+			Replica    types.Replica
+			FieldSpecs []config.FieldSpec
+		}
+		for _, args := range kt.kustomization.Replicas {
+			c.Replica = args
+			c.FieldSpecs = tc.Replicas
+			p := f()
+			err = kt.configureBuiltinPlugin(p, c, bpt)
+			if err != nil {
+				return nil, err
+			}
+			result = append(result, p)
+		}
+		return
+	},
 }

pkg/target/transformerplugin_test.go

@@ -113,7 +113,7 @@ transformers:
 	if err == nil {
 		t.Fatalf("expected error")
 	}
-	if !strings.Contains(err.Error(), "unable to load plugin StringPrefixer") {
+	if !strings.Contains(err.Error(), "unable to load external plugin StringPrefixer") {
 		t.Fatalf("unexpected err: %v", err)
 	}
 }

pkg/transformers/doc.go

@@ -0,0 +1,9 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+// Utilities to aid transformer plugins.
+//
+// TODO: Push remaining code down into the plugins
+// or into an appropriately named utility package.
+// This package made more sense in the pre-plugin days.
+package transformers

pkg/transformers/labelsandannotations.go

@@ -30,23 +30,23 @@ type mapTransformer struct {
 	fieldSpecs []config.FieldSpec
 }
 
-var _ Transformer = &mapTransformer{}
+var _ resmap.Transformer = &mapTransformer{}
 
 // NewLabelsMapTransformer constructs a mapTransformer.
 func NewLabelsMapTransformer(
-	m map[string]string, fs []config.FieldSpec) (Transformer, error) {
+	m map[string]string, fs []config.FieldSpec) (resmap.Transformer, error) {
 	return NewMapTransformer(fs, m)
 }
 
 // NewAnnotationsMapTransformer construct a mapTransformer.
 func NewAnnotationsMapTransformer(
-	m map[string]string, fs []config.FieldSpec) (Transformer, error) {
+	m map[string]string, fs []config.FieldSpec) (resmap.Transformer, error) {
 	return NewMapTransformer(fs, m)
 }
 
 // NewMapTransformer construct a mapTransformer.
 func NewMapTransformer(
-	pc []config.FieldSpec, m map[string]string) (Transformer, error) {
+	pc []config.FieldSpec, m map[string]string) (resmap.Transformer, error) {
 	if m == nil {
 		return NewNoOpTransformer(), nil
 	}

pkg/transformers/multitransformer.go

@@ -24,25 +24,25 @@ import (
 
 // multiTransformer contains a list of transformers.
 type multiTransformer struct {
-	transformers         []Transformer
+	transformers         []resmap.Transformer
 	checkConflictEnabled bool
 }
 
-var _ Transformer = &multiTransformer{}
+var _ resmap.Transformer = &multiTransformer{}
 
 // NewMultiTransformer constructs a multiTransformer.
-func NewMultiTransformer(t []Transformer) Transformer {
+func NewMultiTransformer(t []resmap.Transformer) resmap.Transformer {
 	r := &multiTransformer{
-		transformers:         make([]Transformer, len(t)),
+		transformers:         make([]resmap.Transformer, len(t)),
 		checkConflictEnabled: false}
 	copy(r.transformers, t)
 	return r
 }
 
 // NewMultiTransformerWithConflictCheck constructs a multiTransformer with checking of conflicts.
-func NewMultiTransformerWithConflictCheck(t []Transformer) Transformer {
+func NewMultiTransformerWithConflictCheck(t []resmap.Transformer) resmap.Transformer {
 	r := &multiTransformer{
-		transformers:         make([]Transformer, len(t)),
+		transformers:         make([]resmap.Transformer, len(t)),
 		checkConflictEnabled: true}
 	copy(r.transformers, t)
 	return r

pkg/transformers/namereference.go

@@ -18,11 +18,11 @@ type nameReferenceTransformer struct {
 	backRefs []config.NameBackReferences
 }
 
-var _ Transformer = &nameReferenceTransformer{}
+var _ resmap.Transformer = &nameReferenceTransformer{}
 
 // NewNameReferenceTransformer constructs a nameReferenceTransformer
 // with a given slice of NameBackReferences.
-func NewNameReferenceTransformer(br []config.NameBackReferences) Transformer {
+func NewNameReferenceTransformer(br []config.NameBackReferences) resmap.Transformer {
 	if br == nil {
 		log.Fatal("backrefs not expected to be nil")
 	}

pkg/transformers/nooptransformer.go

@@ -21,10 +21,10 @@ import "sigs.k8s.io/kustomize/v3/pkg/resmap"
 // noOpTransformer contains a no-op transformer.
 type noOpTransformer struct{}
 
-var _ Transformer = &noOpTransformer{}
+var _ resmap.Transformer = &noOpTransformer{}
 
 // NewNoOpTransformer constructs a noOpTransformer.
-func NewNoOpTransformer() Transformer {
+func NewNoOpTransformer() resmap.Transformer {
 	return &noOpTransformer{}
 }
 

pkg/transformers/transformer.go

@@ -1,33 +0,0 @@
-/*
-Copyright 2018 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 transformers has implementations of resmap.ResMap transformers.
-package transformers
-
-import (
-	"sigs.k8s.io/kustomize/v3/pkg/resmap"
-)
-
-// A Transformer modifies an instance of resmap.ResMap.
-type Transformer interface {
-	// Transform modifies data in the argument, e.g. adding labels to resources that can be labelled.
-	Transform(m resmap.ResMap) error
-}
-
-// A Generator creates an instance of resmap.ResMap.
-type Generator interface {
-	Generate() (resmap.ResMap, error)
-}

plugin/builtin/AnnotationsTransformer.go

@@ -15,11 +15,6 @@ type AnnotationsTransformerPlugin struct {
 	FieldSpecs  []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewAnnotationsTransformerPlugin() *AnnotationsTransformerPlugin {
-	return &AnnotationsTransformerPlugin{}
-}
-
 func (p *AnnotationsTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.Annotations = nil
@@ -37,3 +32,7 @@ func (p *AnnotationsTransformerPlugin) Transform(m resmap.ResMap) error {
 	}
 	return t.Transform(m)
 }
+
+func NewAnnotationsTransformerPlugin() resmap.TransformerPlugin {
+	return &AnnotationsTransformerPlugin{}
+}

plugin/builtin/ConfigMapGenerator.go

@@ -16,11 +16,6 @@ type ConfigMapGeneratorPlugin struct {
 	types.ConfigMapArgs
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewConfigMapGeneratorPlugin() *ConfigMapGeneratorPlugin {
-	return &ConfigMapGeneratorPlugin{}
-}
-
 func (p *ConfigMapGeneratorPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, config []byte) (err error) {
 	p.GeneratorOptions = types.GeneratorOptions{}
@@ -40,3 +35,7 @@ func (p *ConfigMapGeneratorPlugin) Config(
 func (p *ConfigMapGeneratorPlugin) Generate() (resmap.ResMap, error) {
 	return p.rf.FromConfigMapArgs(p.ldr, &p.GeneratorOptions, p.ConfigMapArgs)
 }
+
+func NewConfigMapGeneratorPlugin() resmap.GeneratorPlugin {
+	return &ConfigMapGeneratorPlugin{}
+}

plugin/builtin/HashTransformer.go

@@ -12,11 +12,6 @@ type HashTransformerPlugin struct {
 	hasher ifc.KunstructuredHasher
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewHashTransformerPlugin() *HashTransformerPlugin {
-	return &HashTransformerPlugin{}
-}
-
 func (p *HashTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, config []byte) (err error) {
 	p.hasher = rf.RF().Hasher()
@@ -36,3 +31,7 @@ func (p *HashTransformerPlugin) Transform(m resmap.ResMap) error {
 	}
 	return nil
 }
+
+func NewHashTransformerPlugin() resmap.TransformerPlugin {
+	return &HashTransformerPlugin{}
+}

plugin/builtin/ImageTagTransformer.go

@@ -21,11 +21,6 @@ type ImageTagTransformerPlugin struct {
 	FieldSpecs []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewImageTagTransformerPlugin() *ImageTagTransformerPlugin {
-	return &ImageTagTransformerPlugin{}
-}
-
 func (p *ImageTagTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.ImageTag = image.Image{}
@@ -183,3 +178,7 @@ func split(imageName string) (name string, tag string) {
 	tag = imageName[i:]
 	return
 }
+
+func NewImageTagTransformerPlugin() resmap.TransformerPlugin {
+	return &ImageTagTransformerPlugin{}
+}

plugin/builtin/InventoryTransformer.go

@@ -22,11 +22,6 @@ type InventoryTransformerPlugin struct {
 	Policy           string `json:"policy,omitempty" yaml:"policy,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewInventoryTransformerPlugin() *InventoryTransformerPlugin {
-	return &InventoryTransformerPlugin{}
-}
-
 func (p *InventoryTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.ldr = ldr
@@ -127,3 +122,7 @@ func computeRefs(
 	}
 	return
 }
+
+func NewInventoryTransformerPlugin() resmap.TransformerPlugin {
+	return &InventoryTransformerPlugin{}
+}

plugin/builtin/LabelTransformer.go

@@ -15,11 +15,6 @@ type LabelTransformerPlugin struct {
 	FieldSpecs []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewLabelTransformerPlugin() *LabelTransformerPlugin {
-	return &LabelTransformerPlugin{}
-}
-
 func (p *LabelTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.Labels = nil
@@ -37,3 +32,7 @@ func (p *LabelTransformerPlugin) Transform(m resmap.ResMap) error {
 	}
 	return t.Transform(m)
 }
+
+func NewLabelTransformerPlugin() resmap.TransformerPlugin {
+	return &LabelTransformerPlugin{}
+}

plugin/builtin/LegacyOrderTransformer.go

@@ -16,11 +16,6 @@ import (
 // (like ValidatingWebhookConfiguration) last.
 type LegacyOrderTransformerPlugin struct{}
 
-//noinspection GoUnusedGlobalVariable
-func NewLegacyOrderTransformerPlugin() *LegacyOrderTransformerPlugin {
-	return &LegacyOrderTransformerPlugin{}
-}
-
 // Nothing needed for configuration.
 func (p *LegacyOrderTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
@@ -43,3 +38,7 @@ func (p *LegacyOrderTransformerPlugin) Transform(m resmap.ResMap) (err error) {
 	}
 	return nil
 }
+
+func NewLegacyOrderTransformerPlugin() resmap.TransformerPlugin {
+	return &LegacyOrderTransformerPlugin{}
+}

plugin/builtin/NamespaceTransformer.go

@@ -20,11 +20,6 @@ type NamespaceTransformerPlugin struct {
 	FieldSpecs       []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewNamespaceTransformerPlugin() *NamespaceTransformerPlugin {
-	return &NamespaceTransformerPlugin{}
-}
-
 func (p *NamespaceTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.Namespace = ""
@@ -129,3 +124,7 @@ func (o *NamespaceTransformerPlugin) changeNamespace(
 		}
 	}
 }
+
+func NewNamespaceTransformerPlugin() resmap.TransformerPlugin {
+	return &NamespaceTransformerPlugin{}
+}

plugin/builtin/PatchJson6902Transformer.go

@@ -21,11 +21,6 @@ type PatchJson6902TransformerPlugin struct {
 	JsonOp       string            `json:"jsonOp,omitempty" yaml:"jsonOp,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewPatchJson6902TransformerPlugin() *PatchJson6902TransformerPlugin {
-	return &PatchJson6902TransformerPlugin{}
-}
-
 func (p *PatchJson6902TransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.ldr = ldr
@@ -97,3 +92,7 @@ func (p *PatchJson6902TransformerPlugin) Transform(m resmap.ResMap) error {
 	}
 	return obj.UnmarshalJSON(modifiedObj)
 }
+
+func NewPatchJson6902TransformerPlugin() resmap.TransformerPlugin {
+	return &PatchJson6902TransformerPlugin{}
+}

plugin/builtin/PatchStrategicMergeTransformer.go

@@ -18,11 +18,6 @@ type PatchStrategicMergeTransformerPlugin struct {
 	Patches       string                      `json:"patches,omitempty" yaml:"patches,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewPatchStrategicMergeTransformerPlugin() *PatchStrategicMergeTransformerPlugin {
-	return &PatchStrategicMergeTransformerPlugin{}
-}
-
 func (p *PatchStrategicMergeTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.ldr = ldr
@@ -88,3 +83,7 @@ func (p *PatchStrategicMergeTransformerPlugin) Transform(m resmap.ResMap) error
 	}
 	return nil
 }
+
+func NewPatchStrategicMergeTransformerPlugin() resmap.TransformerPlugin {
+	return &PatchStrategicMergeTransformerPlugin{}
+}

plugin/builtin/PatchTransformer.go

@@ -22,11 +22,6 @@ type PatchTransformerPlugin struct {
 	Target       *types.Selector `json:"target,omitempty", yaml:"target,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewPatchTransformerPlugin() *PatchTransformerPlugin {
-	return &PatchTransformerPlugin{}
-}
-
 func (p *PatchTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 	p.ldr = ldr
@@ -146,3 +141,7 @@ func jsonPatchFromBytes(
 	}
 	return jsonpatch.DecodePatch([]byte(ops))
 }
+
+func NewPatchTransformerPlugin() resmap.TransformerPlugin {
+	return &PatchTransformerPlugin{}
+}

plugin/builtin/PrefixSuffixTransformer.go

@@ -21,11 +21,6 @@ type PrefixSuffixTransformerPlugin struct {
 	FieldSpecs []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewPrefixSuffixTransformerPlugin() *PrefixSuffixTransformerPlugin {
-	return &PrefixSuffixTransformerPlugin{}
-}
-
 // Not placed in a file yet due to lack of demand.
 var prefixSuffixFieldSpecsToSkip = []config.FieldSpec{
 	{
@@ -118,3 +113,7 @@ func (p *PrefixSuffixTransformerPlugin) addPrefixSuffix(
 	}
 	return fmt.Sprintf("%s%s%s", p.Prefix, s, p.Suffix), nil
 }
+
+func NewPrefixSuffixTransformerPlugin() resmap.TransformerPlugin {
+	return &PrefixSuffixTransformerPlugin{}
+}

plugin/builtin/ReplicaCountTransformer.go

@@ -20,11 +20,6 @@ type ReplicaCountTransformerPlugin struct {
 	FieldSpecs []config.FieldSpec `json:"fieldSpecs,omitempty" yaml:"fieldSpecs,omitempty"`
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewReplicaCountTransformerPlugin() *ReplicaCountTransformerPlugin {
-	return &ReplicaCountTransformerPlugin{}
-}
-
 func (p *ReplicaCountTransformerPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
 
@@ -88,3 +83,7 @@ func (p *ReplicaCountTransformerPlugin) addReplicas(in interface{}) (interface{}
 	}
 	return p.Replica.Count, nil
 }
+
+func NewReplicaCountTransformerPlugin() resmap.TransformerPlugin {
+	return &ReplicaCountTransformerPlugin{}
+}

plugin/builtin/SecretGenerator.go

@@ -16,11 +16,6 @@ type SecretGeneratorPlugin struct {
 	types.SecretArgs
 }
 
-//noinspection GoUnusedGlobalVariable
-func NewSecretGeneratorPlugin() *SecretGeneratorPlugin {
-	return &SecretGeneratorPlugin{}
-}
-
 func (p *SecretGeneratorPlugin) Config(
 	ldr ifc.Loader, rf *resmap.Factory, config []byte) (err error) {
 	p.GeneratorOptions = types.GeneratorOptions{}
@@ -40,3 +35,7 @@ func (p *SecretGeneratorPlugin) Config(
 func (p *SecretGeneratorPlugin) Generate() (resmap.ResMap, error) {
 	return p.rf.FromSecretArgs(p.ldr, &p.GeneratorOptions, p.SecretArgs)
 }
+
+func NewSecretGeneratorPlugin() resmap.GeneratorPlugin {
+	return &SecretGeneratorPlugin{}
+}

plugin/someteam.example.com/v1/dateprefixer/DatePrefixer.go

@@ -7,7 +7,6 @@ import (
 	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/v3/pkg/ifc"
 	"sigs.k8s.io/kustomize/v3/pkg/resmap"
-	"sigs.k8s.io/kustomize/v3/pkg/transformers"
 	"sigs.k8s.io/kustomize/v3/pkg/transformers/config"
 	"sigs.k8s.io/kustomize/v3/plugin/builtin"
 	"sigs.k8s.io/yaml"
@@ -16,7 +15,7 @@ import (
 // Add a date prefix to the name.
 // A plugin that adapts another plugin.
 type plugin struct {
-	t transformers.Transformer
+	t resmap.Transformer
 }
 
 //nolint: golint

plugin/someteam.example.com/v1/stringprefixer/StringPrefixer.go

@@ -7,7 +7,6 @@ import (
 	"github.com/pkg/errors"
 	"sigs.k8s.io/kustomize/v3/pkg/ifc"
 	"sigs.k8s.io/kustomize/v3/pkg/resmap"
-	"sigs.k8s.io/kustomize/v3/pkg/transformers"
 	"sigs.k8s.io/kustomize/v3/pkg/transformers/config"
 	"sigs.k8s.io/kustomize/v3/pkg/types"
 	"sigs.k8s.io/kustomize/v3/plugin/builtin"
@@ -18,7 +17,7 @@ import (
 // A plugin that adapts another plugin.
 type plugin struct {
 	types.ObjectMeta `json:"metadata,omitempty" yaml:"metadata,omitempty" protobuf:"bytes,1,opt,name=metadata"`
-	t                transformers.Transformer
+	t                resmap.Transformer
 }
 
 //nolint: golint