Keep empty map in kustomize output

api/krusty/extendedpatch_test.go

@@ -156,7 +156,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -232,7 +233,8 @@ spec:
         - mountPath: /tmp/ps
           name: nginx-persistent-storage
       volumes:
-      - name: nginx-persistent-storage
+      - emptyDir: {}
+        name: nginx-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -258,7 +260,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -332,7 +335,8 @@ spec:
         - mountPath: /tmp/ps
           name: nginx-persistent-storage
       volumes:
-      - name: nginx-persistent-storage
+      - emptyDir: {}
+        name: nginx-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -459,7 +463,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -559,7 +564,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -661,7 +667,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -762,7 +769,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -957,7 +965,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -1171,7 +1180,8 @@ spec:
         - mountPath: /tmp/ps
           name: busybox-persistent-storage
       volumes:
-      - name: busybox-persistent-storage
+      - emptyDir: {}
+        name: busybox-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base

api/krusty/inlinepatch_test.go

@@ -79,7 +79,8 @@ spec:
         - mountPath: /tmp/ps
           name: nginx-persistent-storage
       volumes:
-      - name: nginx-persistent-storage
+      - emptyDir: {}
+        name: nginx-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base
@@ -222,7 +223,8 @@ spec:
         - mountPath: /tmp/ps
           name: nginx-persistent-storage
       volumes:
-      - name: nginx-persistent-storage
+      - emptyDir: {}
+        name: nginx-persistent-storage
       - configMap:
           name: configmap-in-base
         name: configmap-in-base

api/krusty/multiplepatch_test.go

@@ -540,7 +540,8 @@ spec:
         - mountPath: /tmp/ps
           name: nginx-persistent-storage
       volumes:
-      - name: nginx-persistent-storage
+      - emptyDir: {}
+        name: nginx-persistent-storage
       - configMap:
           name: staging-team-foo-configmap-in-base-798k5k7g9f
         name: configmap-in-base

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
+// IsEmpty returns true if the RNode is MissingOrNull
-// no fields.
 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

plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer_test.go

@@ -467,7 +467,6 @@ spec:
   replicas: 1
   template:
     metadata:
-      creationTimestamp: null
       labels:
         workload.sas.com/class: stateless
     spec:
@@ -498,45 +497,6 @@ spec:
         name: tmp
 `
 
-// This is the current (incorrect) result we get with kustomize 3.8.1
-const currentCleanedDeployment = `apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    workload.sas.com/class: stateless
-  name: sas-crunchy-data-postgres-operator
-spec:
-  replicas: 1
-  template:
-    metadata:
-      labels:
-        workload.sas.com/class: stateless
-    spec:
-      containers:
-      - envFrom: []
-        image: sas-crunchy-data-operator-api-server
-        imagePullPolicy: IfNotPresent
-        name: apiserver
-        ports:
-        - containerPort: 8443
-        volumeMounts:
-        - mountPath: /security-ssh
-          name: security-ssh
-        - mountPath: /tmp
-          name: tmp
-      imagePullSecrets: []
-      initContainers: []
-      serviceAccountName: postgres-operator
-      tolerations:
-      - effect: NoSchedule
-        key: workload.sas.com/class
-        operator: Equal
-        value: stateful
-      volumes:
-      - name: security-ssh
-      - name: tmp
-`
-
 func TestPatchStrategicMergeTransformerCleanupItems(t *testing.T) {
 	th := kusttest_test.MakeEnhancedHarness(t).
 		PrepBuiltin("PatchStrategicMergeTransformer")
@@ -571,7 +531,7 @@ paths:
 - patch.yaml
 `,
 		anUncleanDeploymentResource,
-		currentCleanedDeployment) // prefer expectedCleanedDeployment
+		expectedCleanedDeployment) // prefer expectedCleanedDeployment
 }
 
 func TestStrategicMergeTransformerNoSchema(t *testing.T) {

plugin/builtin/patchstrategicmergetransformer/go.mod

@@ -9,4 +9,7 @@ require (
 	sigs.k8s.io/yaml v1.2.0
 )
 
-replace sigs.k8s.io/kustomize/api v0.5.1 => ../../../api
+replace (
+	sigs.k8s.io/kustomize/api v0.5.1 => ../../../api
+	sigs.k8s.io/kustomize/kyaml v0.4.2 => ../../../kyaml
+)