Ease doing custom configuration of 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 strings.HasPrefix(l, "//noinspection") {
+			continue
+		}
 		if l == "var "+plugins.PluginSymbol+" plugin" {
-			w.write("func New" + root + "Plugin() *" + root + "Plugin {")
-			w.write("  return &" + root + "Plugin{}")
-			w.write("}")
 			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")
 }
 

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/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 {
@@ -47,21 +43,21 @@ 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())
 	}
 	return g, nil
 }
 
 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
@@ -159,18 +178,18 @@ 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)
 	}
 	registry[regId] = c
 	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)
 }