Switch namespace and patch transformers to kyaml.

plugin/builtin/namespacetransformer/NamespaceTransformer.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"sigs.k8s.io/kustomize/api/filters/namespace"
 	"sigs.k8s.io/kustomize/api/resid"
@@ -35,6 +36,11 @@ func (p *plugin) Config(
 	_ *resmap.PluginHelpers, c []byte) (err error) {
 	p.Namespace = ""
 	p.FieldSpecs = nil
+	if !strings.Contains(string(c), "yamlSupport") {
+		// If not explicitly denied,
+		// activate kyaml-based transformation.
+		p.YAMLSupport = true
+	}
 	return yaml.Unmarshal(c, p)
 }
 

plugin/builtin/patchjson6902transformer/PatchJson6902Transformer.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	jsonpatch "github.com/evanphx/json-patch"
 	"github.com/pkg/errors"
@@ -38,6 +39,11 @@ func (p *plugin) Config(
 	if err != nil {
 		return err
 	}
+	if !strings.Contains(string(c), "yamlSupport") {
+		// If not explicitly denied,
+		// activate kyaml-based transformation.
+		p.YAMLSupport = true
+	}
 	if p.Target.Name == "" {
 		return fmt.Errorf("must specify the target name")
 	}

plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"sigs.k8s.io/kustomize/api/filters/patchstrategicmerge"
 	"sigs.k8s.io/kustomize/api/resmap"
@@ -34,6 +35,11 @@ func (p *plugin) Config(
 	if err != nil {
 		return err
 	}
+	if !strings.Contains(string(c), "yamlSupport") {
+		// If not explicitly denied,
+		// activate kyaml-based transformation.
+		p.YAMLSupport = true
+	}
 	if len(p.Paths) == 0 && p.Patches == "" {
 		return fmt.Errorf("empty file path and empty patch content")
 	}
@@ -79,17 +85,6 @@ func (p *plugin) Transform(m resmap.ResMap) error {
 		}
 		if !p.YAMLSupport {
 			err = target.Patch(patch.Copy())
-			if err != nil {
-				return err
-			}
-			// remove the resource from resmap
-			// when the patch is to $patch: delete that target
-			if len(target.Map()) == 0 {
-				err = m.Remove(target.CurId())
-				if err != nil {
-					return err
-				}
-			}
 		} else {
 			patchCopy := patch.DeepCopy()
 			patchCopy.SetName(target.GetName())
@@ -103,6 +98,19 @@ func (p *plugin) Transform(m resmap.ResMap) error {
 				Patch: node,
 			}, target)
 		}
+		if err != nil {
+			return err
+		}
+		if len(target.Map()) == 0 {
+			// This means all fields have been removed from the object.
+			// This can happen if a patch required deletion of the
+			// entire resource (not just a part of it).  This means
+			// the overall resmap must shrink by one.
+			err = m.Remove(target.CurId())
+			if err != nil {
+				return err
+			}
+		}
 	}
 	return nil
 }

plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer_test.go

@@ -1208,9 +1208,89 @@ func TestMultipleNamespaces(t *testing.T) {
 	}
 }
 
-// We don't run this for the kyaml implementation since we don't support
-// the strategic merge patch directives (yet).
-func TestPatchStrategicMergeTransformerPatchDelete(t *testing.T) {
+func TestPatchStrategicMergeTransformerPatchDelete1(t *testing.T) {
+	th := kusttest_test.MakeEnhancedHarness(t).
+		PrepBuiltin("PatchStrategicMergeTransformer")
+	defer th.Reset()
+
+	th.WriteF("patch.yaml", `
+apiVersion: apps/v1
+metadata:
+  name: myDeploy
+kind: Deployment
+spec:
+  replica: 2
+  template:
+    $patch: delete
+    metadata:
+      labels:
+        old-label: old-value
+    spec:
+      containers:
+      - name: nginx
+        image: nginx
+`)
+
+	rm := th.LoadAndRunTransformer(`
+apiVersion: builtin
+kind: PatchStrategicMergeTransformer
+metadata:
+  name: notImportantHere
+paths:
+- patch.yaml
+`, target)
+
+	th.AssertActualEqualsExpected(rm, `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: myDeploy
+spec:
+  replica: 2
+`)
+}
+
+func TestPatchStrategicMergeTransformerPatchDelete2(t *testing.T) {
+	th := kusttest_test.MakeEnhancedHarness(t).
+		PrepBuiltin("PatchStrategicMergeTransformer")
+	defer th.Reset()
+
+	th.WriteF("patch.yaml", `
+apiVersion: apps/v1
+metadata:
+  name: myDeploy
+kind: Deployment
+spec:
+  $patch: delete
+  replica: 2
+  template:
+    metadata:
+      labels:
+        old-label: old-value
+    spec:
+      containers:
+      - name: nginx
+        image: nginx
+`)
+
+	rm := th.LoadAndRunTransformer(`
+apiVersion: builtin
+kind: PatchStrategicMergeTransformer
+metadata:
+  name: notImportantHere
+paths:
+- patch.yaml
+`, target)
+
+	th.AssertActualEqualsExpected(rm, `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: myDeploy
+`)
+}
+
+func TestPatchStrategicMergeTransformerPatchDelete3(t *testing.T) {
 	th := kusttest_test.MakeEnhancedHarness(t).
 		PrepBuiltin("PatchStrategicMergeTransformer")
 	defer th.Reset()
@@ -1234,3 +1314,4 @@ paths:
 
 	th.AssertActualEqualsExpected(rm, ``)
 }
+

plugin/builtin/patchtransformer/PatchTransformer.go

@@ -38,6 +38,11 @@ func (p *plugin) Config(
 	if err != nil {
 		return err
 	}
+	if !strings.Contains(string(c), "yamlSupport") {
+		// If not explicitly denied,
+		// activate kyaml-based transformation.
+		p.YAMLSupport = true
+	}
 	p.Patch = strings.TrimSpace(p.Patch)
 	if p.Patch == "" && p.Path == "" {
 		return fmt.Errorf(