Keep empty map in kustomize output

kyaml/yaml/fns.go

@@ -67,14 +67,15 @@ func (e ElementSetter) Filter(rn *RNode) (*RNode, error) {
 	matchingElementFound := false
 	for i := range rn.YNode().Content {
 		elem := rn.Content()[i]
+		newNode := NewRNode(elem)
 
 		// empty elements are not valid -- they at least need an associative key
-		if IsEmpty(NewRNode(elem)) {
+		if IsEmpty(newNode) || IsEmptyMap(newNode) {
 			continue
 		}
 
 		// check if this is the element we are matching
-		val, err := NewRNode(elem).Pipe(FieldMatcher{Name: e.Key, StringValue: e.Value})
+		val, err := newNode.Pipe(FieldMatcher{Name: e.Key, StringValue: e.Value})
 		if err != nil {
 			return nil, err
 		}

kyaml/yaml/merge2/element_test.go

@@ -302,7 +302,7 @@ kind: Deployment
 spec:
   template:
     spec:
-      containers: {}
+      containers: []
 `,
 		dest: `
 apiVersion: apps/v1

kyaml/yaml/merge2/list_test.go

@@ -262,7 +262,7 @@ kind: Deployment
 	{description: `remove list -- empty in src`,
 		source: `
 kind: Deployment
-items: {}
+items: []
 `,
 		dest: `
 kind: Deployment
@@ -273,7 +273,7 @@ items:
 `,
 		expected: `
 kind: Deployment
-items: {}
+items: []
 `,
 	},
 }

kyaml/yaml/merge2/map_test.go

@@ -167,8 +167,8 @@ spec: {}
 		expected: `
 kind: Deployment
 spec:
-  foo: bar1
   baz: buz
+  foo: bar1
 `,
 	},
 

kyaml/yaml/merge2/scalar_test.go

@@ -91,7 +91,7 @@ kind: Deployment
 	{description: `remove scalar -- empty in src`,
 		source: `
 kind: Deployment
-field: {}
+field: null
 `,
 		dest: `
 kind: Deployment
@@ -99,7 +99,6 @@ field: value1
 `,
 		expected: `
 kind: Deployment
-field: {}
 `,
 	},
 

kyaml/yaml/merge3/element_test.go

@@ -371,7 +371,7 @@ kind: Deployment
 spec:
   template:
     spec:
-      containers: {}
+      containers: null
 `,
 		update: `
 apiVersion: apps/v1
@@ -379,7 +379,7 @@ kind: Deployment
 spec:
   template:
     spec:
-      containers: {}
+      containers: null
 `,
 		local: `
 apiVersion: apps/v1
@@ -584,7 +584,7 @@ kind: Deployment
 spec:
   template:
     spec:
-      containers: {}
+      containers: null
 `,
 		local: `
 apiVersion: apps/v1

kyaml/yaml/types.go

@@ -44,16 +44,17 @@ func IsMissingOrNull(node *RNode) bool {
 	return node == nil || node.YNode() == nil || node.YNode().Tag == NullNodeTag
 }
 
-// IsEmpty returns true if the RNode is MissingOrNull, or is either a MappingNode with
-// no fields.
+// IsEmpty returns true if the RNode is MissingOrNull
 func IsEmpty(node *RNode) bool {
-	if IsMissingOrNull(node) {
+	return IsMissingOrNull(node)
+}
+
+// IsEmptyMap returns true if the RNode is an empty node or an empty map
+func IsEmptyMap(node *RNode) bool {
+	if IsEmpty(node) {
 		return true
 	}
 
-	// Empty sequence is a special case and temporarily not considered as empty here.
-	// Some users may want to keep empty sequence for compatibility reason.
-	// For example, use JSON 6902 patch.
 	return node.YNode().Kind == yaml.MappingNode && len(node.YNode().Content) == 0
 }
 

kyaml/yaml/types_test.go

@@ -221,19 +221,19 @@ func TestIsEmpty_Arrays(t *testing.T) {
 func TestIsEmpty_Maps(t *testing.T) {
 	node := NewMapRNode(nil)
 	// empty map
-	if !IsEmpty(node) {
+	if !IsEmptyMap(node) {
 		t.Fatalf("input: empty map")
 	}
 	// map with 1 item
 	node = NewMapRNode(&map[string]string{
 		"foo": "bar",
 	})
-	if IsEmpty(node) {
+	if IsEmptyMap(node) {
 		t.Fatalf("input: map with 1 item")
 	}
 	// delete the item in map
 	node.value.Content = nil
-	if !IsEmpty(node) {
+	if !IsEmptyMap(node) {
 		t.Fatalf("input: empty map")
 	}
 }

kyaml/yaml/walk/associative_sequence.go

@@ -51,7 +51,7 @@ func (l *Walker) walkAssociativeSequence() (*yaml.RNode, error) {
 			if err != nil {
 				return nil, err
 			}
-			if yaml.IsEmpty(val) {
+			if yaml.IsEmpty(val) || yaml.IsEmptyMap(val) {
 				_, err = dest.Pipe(yaml.ElementSetter{Key: key, Value: value})
 				if err != nil {
 					return nil, err