generate configmap for pruning

k8sdeps/transformer/factory.go

@@ -20,8 +20,10 @@ package transformer
 import (
 	"sigs.k8s.io/kustomize/k8sdeps/transformer/hash"
 	"sigs.k8s.io/kustomize/k8sdeps/transformer/patch"
+	"sigs.k8s.io/kustomize/k8sdeps/transformer/prune"
 	"sigs.k8s.io/kustomize/pkg/resource"
 	"sigs.k8s.io/kustomize/pkg/transformers"
+	"sigs.k8s.io/kustomize/pkg/types"
 )
 
 // FactoryImpl makes patch transformer and name hash transformer
@@ -41,3 +43,7 @@ func (p *FactoryImpl) MakePatchTransformer(slice []*resource.Resource, rf *resou
 func (p *FactoryImpl) MakeHashTransformer() transformers.Transformer {
 	return hash.NewNameHashTransformer()
 }
+
+func (p *FactoryImpl) MakePruneTransformer(arg *types.Prune, namespace string, append bool) transformers.Transformer {
+	return prune.NewPruneTransformer(arg, namespace, append)
+}

k8sdeps/transformer/hash/hash.go

@@ -20,6 +20,7 @@ import (
 	"crypto/sha256"
 	"encoding/json"
 	"fmt"
+	"sort"
 
 	"k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
@@ -86,6 +87,21 @@ func SecretHash(sec *v1.Secret) (string, error) {
 	return h, nil
 }
 
+// SortArrayAndComputeHash sorts a string array and
+// returns a hash for it
+func SortArrayAndComputeHash(s []string) (string, error) {
+	sort.Strings(s)
+	data, err := json.Marshal(s)
+	if err != nil {
+		return "", err
+	}
+	h, err := encodeHash(hash(string(data)))
+	if err != nil {
+		return "", err
+	}
+	return h, nil
+}
+
 // encodeConfigMap encodes a ConfigMap.
 // Data, Kind, and Name are taken into account.
 func encodeConfigMap(cm *v1.ConfigMap) (string, error) {

k8sdeps/transformer/hash/hash_test.go

@@ -90,6 +90,28 @@ func TestSecretHash(t *testing.T) {
 	}
 }
 
+func TestArrayHash(t *testing.T) {
+	array1 := []string{"a", "b", "c"}
+	array2 := []string{"c", "b", "a"}
+	h1, err := SortArrayAndComputeHash(array1)
+	if err != nil {
+		t.Errorf("unexpected error %v", err)
+	}
+	if h1 == "" {
+		t.Errorf("failed to hash %v", array1)
+	}
+	h2, err := SortArrayAndComputeHash(array2)
+	if err != nil {
+		t.Errorf("unexpected error %v", err)
+	}
+	if h2 == "" {
+		t.Errorf("failed to hash %v", array2)
+	}
+	if h1 != h2 {
+		t.Errorf("hash is not consistent with reordered list: %s %s", h1, h2)
+	}
+}
+
 func TestEncodeConfigMap(t *testing.T) {
 	cases := []struct {
 		desc   string

k8sdeps/transformer/prune/prune.go

@@ -0,0 +1,110 @@
+/*
+Copyright 2019 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 prune
+
+import (
+	"fmt"
+	"sigs.k8s.io/kustomize/k8sdeps/kunstruct"
+	"sigs.k8s.io/kustomize/k8sdeps/transformer/hash"
+	"sigs.k8s.io/kustomize/pkg/gvk"
+	"sigs.k8s.io/kustomize/pkg/resid"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+	"sigs.k8s.io/kustomize/pkg/resource"
+	"sigs.k8s.io/kustomize/pkg/transformers"
+	"sigs.k8s.io/kustomize/pkg/types"
+)
+
+//const PruneAnnotation = "kustomize.k8s.io/PruneRevision"
+const PruneAnnotation = "current"
+
+// pruneTransformer compute the ConfigMap used in prune
+type pruneTransformer struct {
+	append      bool
+	cmName      string
+	cmNamespace string
+}
+
+var _ transformers.Transformer = &pruneTransformer{}
+
+// NewPruneTransformer makes a pruneTransformer.
+func NewPruneTransformer(p *types.Prune, namespace string, append bool) transformers.Transformer {
+	if p == nil || p.Type != "alphaConfigMap" || p.AlphaConfigMap.Namespace != namespace {
+		return transformers.NewNoOpTransformer()
+	}
+	return &pruneTransformer{
+		append:      append,
+		cmName:      p.AlphaConfigMap.Name,
+		cmNamespace: p.AlphaConfigMap.Namespace,
+	}
+}
+
+// Transform generates a prune ConfigMap based on the input ResMap.
+// this tranformer doesn't change existing resources -
+// it just visits resources and accumulates information to make a new ConfigMap.
+// The prune ConfigMap is used to support the pruning command in the client side tool,
+// which is proposed in https://github.com/kubernetes/enhancements/pull/810
+func (o *pruneTransformer) Transform(m resmap.ResMap) error {
+	keys := []string{}
+	for id, r := range m {
+		s := id.PruneString()
+		keys = append(keys, s)
+		for _, refid := range r.GetRefBy() {
+			keys = append(keys, s+"---"+refid.PruneString())
+		}
+	}
+	h, err := hash.SortArrayAndComputeHash(keys)
+	if err != nil {
+		return err
+	}
+
+	args := &types.ConfigMapArgs{}
+	args.Name = o.cmName
+	args.Namespace = o.cmNamespace
+	for _, key := range keys {
+		args.LiteralSources = append(args.LiteralSources,
+			key+"="+h)
+	}
+	opts := &types.GeneratorOptions{
+		Annotations: make(map[string]string),
+	}
+	opts.Annotations[PruneAnnotation] = h
+
+	kf := kunstruct.NewKunstructuredFactoryImpl()
+	k, err := kf.MakeConfigMap(nil, opts, args)
+	if err != nil {
+		return err
+	}
+
+	if !o.append {
+		for k := range m {
+			delete(m, k)
+		}
+	}
+
+	id := resid.NewResIdWithPrefixNamespace(
+		gvk.Gvk{
+			Version: "v1",
+			Kind:    "ConfigMap",
+		},
+		o.cmName,
+		"", o.cmNamespace)
+	if _, ok := m[id]; ok {
+		return fmt.Errorf("id %v is already used, please use a different name in the prune field", id)
+	}
+	m[id] = resource.NewFactory(kf).FromKunstructured(k)
+	return nil
+}

k8sdeps/transformer/prune/prune_test.go

@@ -0,0 +1,171 @@
+/*
+Copyright 2019 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 prune
+
+import (
+	"reflect"
+	"testing"
+
+	"sigs.k8s.io/kustomize/k8sdeps/kunstruct"
+	"sigs.k8s.io/kustomize/pkg/gvk"
+	"sigs.k8s.io/kustomize/pkg/resid"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+	"sigs.k8s.io/kustomize/pkg/resource"
+	"sigs.k8s.io/kustomize/pkg/types"
+)
+
+var secret = gvk.Gvk{Version: "v1", Kind: "Secret"}
+var cmap = gvk.Gvk{Version: "v1", Kind: "ConfigMap"}
+var deploy = gvk.Gvk{Group: "apps", Version: "v1", Kind: "Deployment"}
+
+func makeResMap() resmap.ResMap {
+	rf := resource.NewFactory(
+		kunstruct.NewKunstructuredFactoryImpl())
+	objs := resmap.ResMap{
+		resid.NewResId(cmap, "cm1"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "ConfigMap",
+				"metadata": map[string]interface{}{
+					"name": "cm1",
+				},
+			}),
+		resid.NewResId(secret, "secret1"): rf.FromMap(
+			map[string]interface{}{
+				"apiVersion": "v1",
+				"kind":       "Secret",
+				"metadata": map[string]interface{}{
+					"name": "secret1",
+				},
+			}),
+		resid.NewResId(deploy, "deploy1"): rf.FromMap(
+			map[string]interface{}{
+				"group":      "apps",
+				"apiVersion": "v1",
+				"kind":       "Deployment",
+				"metadata": map[string]interface{}{
+					"name": "deploy1",
+				},
+				"spec": map[string]interface{}{
+					"template": map[string]interface{}{
+						"spec": map[string]interface{}{
+							"containers": []interface{}{
+								map[string]interface{}{
+									"name":  "nginx",
+									"image": "nginx:1.7.9",
+									"env": []interface{}{
+										map[string]interface{}{
+											"name": "CM_FOO",
+											"valueFrom": map[string]interface{}{
+												"configMapKeyRef": map[string]interface{}{
+													"name": "cm1",
+													"key":  "somekey",
+												},
+											},
+										},
+									},
+									"envFrom": []interface{}{
+										map[string]interface{}{
+											"configMapRef": map[string]interface{}{
+												"name": "cm1",
+												"key":  "somekey",
+											},
+										},
+										map[string]interface{}{
+											"secretRef": map[string]interface{}{
+												"name": "secret1",
+												"key":  "somekey",
+											},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+			}),
+	}
+	objs[resid.NewResId(cmap, "cm1")].AppendRefBy(resid.NewResId(deploy, "deploy1"))
+	objs[resid.NewResId(secret, "secret1")].AppendRefBy(resid.NewResId(deploy, "deploy1"))
+	return objs
+}
+
+func TestPruneTransformer(t *testing.T) {
+	rf := resource.NewFactory(
+		kunstruct.NewKunstructuredFactoryImpl())
+
+	// hash is derived based on all keys in the ConfigMap data field.
+	// It is added to annotations as
+	//   current: hash
+	// When seeing the same annotation, prune binary assumes no
+	// clean up is needed
+	hash := "k777d7h45b"
+	//  This is the root or inventory object which tracks all
+	// the applied resources - this is the thing we expect the transformer to create.
+	pruneMap := rf.FromMap(
+		map[string]interface{}{
+			"apiVersion": "v1",
+			"kind":       "ConfigMap",
+			"metadata": map[string]interface{}{
+				"name":      "pruneCM",
+				"namespace": "default",
+				"annotations": map[string]interface{}{
+					"current": hash,
+				},
+			},
+			"data": map[string]interface{}{
+				"_ConfigMap__cm1":                             hash,
+				"_Secret__secret1":                            hash,
+				"apps_Deployment__deploy1":                    hash,
+				"_ConfigMap__cm1---apps_Deployment__deploy1":  hash,
+				"_Secret__secret1---apps_Deployment__deploy1": hash,
+			},
+		})
+	expected := resmap.ResMap{
+		resid.NewResIdWithPrefixNamespace(cmap, "pruneCM", "", "default"): pruneMap,
+	}
+
+	p := &types.Prune{
+		Type: "alphaConfigMap",
+		AlphaConfigMap: types.NameArgs{
+			Name:      "pruneCM",
+			Namespace: "default",
+		},
+	}
+	objs := makeResMap()
+
+	// include the original resmap; only return the ConfigMap for pruning
+	tran := NewPruneTransformer(p, "default", false)
+	tran.Transform(objs)
+
+	if !reflect.DeepEqual(objs, expected) {
+		err := expected.ErrorIfNotEqual(objs)
+		t.Fatalf("actual doesn't match expected: %v", err)
+	}
+
+	objs = makeResMap()
+	expected = objs.DeepCopy(rf)
+	expected[resid.NewResIdWithPrefixNamespace(cmap, "pruneCM", "", "default")] = pruneMap
+	// append the ConfigMap for pruning to the original resmap
+	tran = NewPruneTransformer(p, "default", true)
+	tran.Transform(objs)
+
+	if !reflect.DeepEqual(objs, expected) {
+		err := expected.ErrorIfNotEqual(objs)
+		t.Fatalf("actual doesn't match expected: %v", err)
+	}
+}

pkg/commands/build/build.go

@@ -84,6 +84,8 @@ func NewCmdBuild(
 		&o.outputPath,
 		"output", "o", "",
 		"If specified, write the build output to this path.")
+
+	cmd.AddCommand(NewCmdBuildPrune(out, fs, rf, ptf, b))
 	return cmd
 }
 
@@ -130,3 +132,55 @@ func (o *Options) RunBuild(
 	_, err = out.Write(res)
 	return err
 }
+
+func (o *Options) RunBuildPrune(
+	out io.Writer, fSys fs.FileSystem,
+	rf *resmap.Factory, ptf transformer.Factory,
+	b bool) error {
+	ldr, err := loader.NewLoader(o.kustomizationPath, fSys)
+	if err != nil {
+		return err
+	}
+	defer ldr.Cleanup()
+	kt, err := target.NewKustTarget(ldr, rf, ptf, b)
+	if err != nil {
+		return err
+	}
+	allResources, err := kt.MakePruneConfigMap()
+	if err != nil {
+		return err
+	}
+	// Output the objects.
+	res, err := allResources.EncodeAsYaml()
+	if err != nil {
+		return err
+	}
+	if o.outputPath != "" {
+		return fSys.WriteFile(o.outputPath, res)
+	}
+	_, err = out.Write(res)
+	return err
+}
+
+func NewCmdBuildPrune(
+	out io.Writer, fs fs.FileSystem,
+	rf *resmap.Factory,
+	ptf transformer.Factory,
+	b bool) *cobra.Command {
+	var o Options
+
+	cmd := &cobra.Command{
+		Use:          "prune [path]",
+		Short:        "Print configmap to prune previous applied objects",
+		Example:      examples,
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			err := o.Validate(args)
+			if err != nil {
+				return err
+			}
+			return o.RunBuildPrune(out, fs, rf, ptf, b)
+		},
+	}
+	return cmd
+}

pkg/commands/kustfile/kustomizationfile.go

@@ -69,6 +69,7 @@ func determineFieldOrder() []string {
 		"Configurations",
 		"Generators",
 		"Transformers",
+		"Prune",
 	}
 
 	// Add deprecated fields here.

pkg/commands/kustfile/kustomizationfile_test.go

@@ -48,6 +48,7 @@ func TestFieldOrder(t *testing.T) {
 		"Configurations",
 		"Generators",
 		"Transformers",
+		"Prune",
 	}
 	actual := determineFieldOrder()
 	if len(expected) != len(actual) {

pkg/ifc/transformer/factory.go

@@ -20,10 +20,12 @@ package transformer
 import (
 	"sigs.k8s.io/kustomize/pkg/resource"
 	"sigs.k8s.io/kustomize/pkg/transformers"
+	"sigs.k8s.io/kustomize/pkg/types"
 )
 
 // Factory makes transformers
 type Factory interface {
 	MakePatchTransformer(slice []*resource.Resource, rf *resource.Factory) (transformers.Transformer, error)
 	MakeHashTransformer() transformers.Transformer
+	MakePruneTransformer(p *types.Prune, namespace string, append bool) transformers.Transformer
 }

pkg/resid/resid.go

@@ -205,3 +205,13 @@ func (n ResId) prefixList() []string {
 func (n ResId) suffixList() []string {
 	return strings.Split(n.suffix, ":")
 }
+
+// PruneString returns a string which can be used
+// as a key in a Prune ConfigMap
+func (n ResId) PruneString() string {
+	name := n.prefix + n.name + n.suffix
+	return n.gvKind.Group +
+		"_" + n.gvKind.Kind +
+		"_" + n.namespace +
+		"_" + name
+}

pkg/resource/resource.go

@@ -30,6 +30,7 @@ import (
 type Resource struct {
 	ifc.Kunstructured
 	options *types.GenArgs
+	refBy   []resid.ResId
 }
 
 // String returns resource as JSON.
@@ -43,10 +44,16 @@ func (r *Resource) String() string {
 
 // DeepCopy returns a new copy of resource
 func (r *Resource) DeepCopy() *Resource {
-	return &Resource{
+	rc := &Resource{
 		Kunstructured: r.Kunstructured.Copy(),
 		options:       r.options,
 	}
+	if len(r.refBy) > 0 {
+		refby := make([]resid.ResId, len(r.refBy))
+		copy(refby, r.refBy)
+		rc.refBy = refby
+	}
+	return rc
 }
 
 // Behavior returns the behavior for the resource.
@@ -65,12 +72,26 @@ func (r *Resource) Id() resid.ResId {
 	return resid.NewResIdWithPrefixNamespace(r.GetGvk(), r.GetName(), "", namespace)
 }
 
+// GetRefBy returns the ResIds that referred to current resource
+func (r *Resource) GetRefBy() []resid.ResId {
+	return r.refBy
+}
+
+// AppendRefBy appends a ResId into the refBy list
+func (r *Resource) AppendRefBy(id resid.ResId) {
+	r.refBy = append(r.refBy, id)
+}
+
 // Merge performs merge with other resource.
 func (r *Resource) Merge(other *Resource) {
 	r.Replace(other)
 	mergeConfigmap(r.Map(), other.Map(), r.Map())
 }
 
+func (r *Resource) PruneString() string {
+	return r.Id().PruneString()
+}
+
 // Replace performs replace with other resource.
 func (r *Resource) Replace(other *Resource) {
 	r.SetLabels(mergeStringMaps(other.GetLabels(), r.GetLabels()))

pkg/resource/resource_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package resource_test
 
 import (
+	"reflect"
 	"testing"
 
 	"sigs.k8s.io/kustomize/k8sdeps/kunstruct"
@@ -94,3 +95,20 @@ func TestResourceId(t *testing.T) {
 		}
 	}
 }
+
+func TestDeepCopy(t *testing.T) {
+	r := factory.FromMap(
+		map[string]interface{}{
+			"apiVersion": "apps/v1",
+			"kind":       "Deployment",
+			"metadata": map[string]interface{}{
+				"name": "pooh",
+			},
+		})
+	r.AppendRefBy(resid.NewResId(gvk.Gvk{Group: "somegroup", Kind: "MyKind"}, "random"))
+
+	cr := r.DeepCopy()
+	if !reflect.DeepEqual(r, cr) {
+		t.Errorf("expected %v\nbut got%v", r, cr)
+	}
+}

pkg/target/kusttarget.go

@@ -143,7 +143,47 @@ func (kt *KustTarget) MakeCustomizedResMap() (resmap.ResMap, error) {
 	}
 	// With all the back references fixed, it's OK to resolve Vars.
 	err = ra.ResolveVars()
-	return ra.ResMap(), err
+	if err != nil {
+		return nil, err
+	}
+
+	rm := ra.ResMap()
+	pt := kt.tFactory.MakePruneTransformer(kt.kustomization.Prune, kt.kustomization.Namespace, true)
+	err = pt.Transform(rm)
+	if err != nil {
+		return nil, err
+	}
+	return rm, nil
+}
+
+func (kt *KustTarget) MakePruneConfigMap() (resmap.ResMap, error) {
+	ra, err := kt.AccumulateTarget()
+	if err != nil {
+		return nil, err
+	}
+	err = ra.Transform(kt.tFactory.MakeHashTransformer())
+	if err != nil {
+		return nil, err
+	}
+	// Given that names have changed (prefixs/suffixes added),
+	// fix all the back references to those names.
+	err = ra.FixBackReferences()
+	if err != nil {
+		return nil, err
+	}
+	// With all the back references fixed, it's OK to resolve Vars.
+	err = ra.ResolveVars()
+	if err != nil {
+		return nil, err
+	}
+
+	rm := ra.ResMap()
+	pt := kt.tFactory.MakePruneTransformer(kt.kustomization.Prune, kt.kustomization.Namespace, false)
+	err = pt.Transform(rm)
+	if err != nil {
+		return nil, err
+	}
+	return rm, nil
 }
 
 func (kt *KustTarget) shouldAddHashSuffixesToGeneratedResources() bool {

pkg/target/pruneconfigmap_test.go

@@ -0,0 +1,180 @@
+/*
+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 target_test
+
+import (
+	"testing"
+)
+
+func TestPruneConfigMap(t *testing.T) {
+	th := NewKustTestHarness(t, "/app/base")
+	th.writeK("/app/base", `
+resources:
+- deployment.yaml
+- service.yaml
+- secret.yaml
+
+prune:
+  type: alphaConfigMap
+  alphaConfigMap:
+    name: haha
+    namespace: default
+
+namePrefix: my-
+namespace: default
+`)
+	th.writeF("/app/base/deployment.yaml", `
+apiVersion: apps/v1beta2
+kind: Deployment
+metadata:
+  name: mysql
+  labels:
+    app: mysql
+spec:
+  selector:
+    matchLabels:
+      app: mysql
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: mysql
+    spec:
+      containers:
+      - image: mysql:5.6
+        name: mysql
+        env:
+        - name: MYSQL_ROOT_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: pass
+              key: password
+        ports:
+        - containerPort: 3306
+          name: mysql
+        volumeMounts:
+        - name: mysql-persistent-storage
+          mountPath: /var/lib/mysql
+      volumes:
+      - name: mysql-persistent-storage
+        emptyDir: {}
+`)
+	th.writeF("/app/base/service.yaml", `
+apiVersion: v1
+kind: Service
+metadata:
+  name: mmmysql
+  labels:
+    app: mysql
+spec:
+  ports:
+    - port: 3306
+  selector:
+    app: mysql
+`)
+	th.writeF("/app/base/secret.yaml", `
+apiVersion: v1
+kind: Secret
+metadata:
+  name: pass
+type: Opaque
+data:
+  # Default password is "admin".
+  password: YWRtaW4=
+  username: jingfang
+`)
+
+	m, err := th.makeKustTarget().MakeCustomizedResMap()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	th.assertActualEqualsExpected(m, `
+apiVersion: v1
+data:
+  _Secret_default_my-pass: 54f87m6fd6
+  _Secret_default_my-pass---apps_Deployment_default_my-mysql: 54f87m6fd6
+  _Service_default_my-mmmysql: 54f87m6fd6
+  apps_Deployment_default_my-mysql: 54f87m6fd6
+kind: ConfigMap
+metadata:
+  annotations:
+    current: 54f87m6fd6
+  name: haha
+  namespace: default
+---
+apiVersion: v1
+data:
+  password: YWRtaW4=
+  username: jingfang
+kind: Secret
+metadata:
+  name: my-pass
+  namespace: default
+type: Opaque
+---
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: mysql
+  name: my-mmmysql
+  namespace: default
+spec:
+  ports:
+  - port: 3306
+  selector:
+    app: mysql
+---
+apiVersion: apps/v1beta2
+kind: Deployment
+metadata:
+  labels:
+    app: mysql
+  name: my-mysql
+  namespace: default
+spec:
+  selector:
+    matchLabels:
+      app: mysql
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: mysql
+    spec:
+      containers:
+      - env:
+        - name: MYSQL_ROOT_PASSWORD
+          valueFrom:
+            secretKeyRef:
+              key: password
+              name: my-pass
+        image: mysql:5.6
+        name: mysql
+        ports:
+        - containerPort: 3306
+          name: mysql
+        volumeMounts:
+        - mountPath: /var/lib/mysql
+          name: mysql-persistent-storage
+      volumes:
+      - emptyDir: {}
+        name: mysql-persistent-storage
+`)
+}

pkg/transformers/namereference.go

@@ -21,6 +21,7 @@ import (
 	"log"
 
 	"sigs.k8s.io/kustomize/pkg/gvk"
+	"sigs.k8s.io/kustomize/pkg/resid"
 	"sigs.k8s.io/kustomize/pkg/resmap"
 	"sigs.k8s.io/kustomize/pkg/transformers/config"
 )
@@ -70,7 +71,7 @@ func (o *nameReferenceTransformer) Transform(m resmap.ResMap) error {
 						m[id].Map(), fSpec.PathSlice(),
 						fSpec.CreateIfNotPresent,
 						o.updateNameReference(
-							backRef.Gvk, m.FilterBy(id)))
+							id, backRef.Gvk, m.FilterBy(id)))
 					if err != nil {
 						return err
 					}
@@ -82,7 +83,7 @@ func (o *nameReferenceTransformer) Transform(m resmap.ResMap) error {
 }
 
 func (o *nameReferenceTransformer) updateNameReference(
-	backRef gvk.Gvk, m resmap.ResMap) func(in interface{}) (interface{}, error) {
+	rid resid.ResId, backRef gvk.Gvk, m resmap.ResMap) func(in interface{}) (interface{}, error) {
 	return func(in interface{}) (interface{}, error) {
 		switch in.(type) {
 		case string:
@@ -98,6 +99,7 @@ func (o *nameReferenceTransformer) updateNameReference(
 					}
 					// Return transformed name of the object,
 					// complete with prefixes, hashes, etc.
+					res.AppendRefBy(rid)
 					return res.GetName(), nil
 				}
 			}
@@ -123,6 +125,7 @@ func (o *nameReferenceTransformer) updateNameReference(
 					for _, index := range indexes {
 						l[index] = res.GetName()
 					}
+					res.AppendRefBy(rid)
 					return l, nil
 				}
 			}

pkg/transformers/namereference_test.go

@@ -618,6 +618,7 @@ func TestNameReferencePersistentVolumeHappyRun(t *testing.T) {
 				},
 			}),
 	}
+	expected[resid.NewResId(pv, "volume1")].AppendRefBy(resid.NewResId(pvc, "claim1"))
 	nrt := NewNameReferenceTransformer(defaultTransformerConfig.NameReference)
 	err := nrt.Transform(m)
 	if err != nil {

pkg/types/kustomization.go

@@ -136,6 +136,9 @@ type Kustomization struct {
 
 	// Transformers is a list of files containing transformers
 	Transformers []string `json:"transformers,omitempty" yaml:"transformers,omitempty"`
+
+	// Name of the ConfigMap used in Prune
+	Prune *Prune `json:"prune,omitempty" yaml:"prune:omitempty"`
 }
 
 // DealWithMissingFields fills the missing fields
@@ -289,3 +292,13 @@ type KVSource struct {
 	Name       string     `json:"name,omitempty" yaml:"name,omitempty"`
 	Args       []string   `json:"args,omitempty" yaml:"args,omitempty"`
 }
+
+type Prune struct {
+	Type           string   `json:"type,omitempty" yaml:"type,omitempty"`
+	AlphaConfigMap NameArgs `json:"alphaConfigMap,omitempty" yaml:"alphaConfigMap,omitempty"`
+}
+
+type NameArgs struct {
+	Name      string `json:"name,omitempty" yaml:"name,omitempty"`
+	Namespace string `json:"namespace,omitempty" yaml:"namespace,omitempty"`
+}