kustomize transformers to create fields if they are null

api/filters/annotations/annotations.go

@@ -32,6 +32,7 @@ func (f Filter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
 					FsSlice:    f.FsSlice,
 					SetValue:   fsslice.SetEntry(k, f.Annotations[k], yaml.StringTag),
 					CreateKind: yaml.MappingNode, // Annotations are MappingNodes.
+					CreateTag:  "!!map",
 				}); err != nil {
 					return nil, err
 				}

api/filters/annotations/annotations_test.go

@@ -186,6 +186,30 @@ metadata:
 				"f": "true1",
 			}},
 		},
+
+		// test quoting of values which are not considered strings in yaml 1.1
+		"null_annotations": {
+			input: `
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+  annotations: null
+`,
+			expectedOutput: `
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+  annotations:
+    a: a1
+    b: b1
+`,
+			filter: Filter{Annotations: annoMap{
+				"a": "a1",
+				"b": "b1",
+			}},
+		},
 	}
 
 	for tn, tc := range testCases {

api/filters/fsslice/fieldspec_filter.go

@@ -23,6 +23,8 @@ type fieldSpecFilter struct {
 	// CreateKind defines the type of node to create if the field is not found
 	CreateKind yaml.Kind
 
+	CreateTag string
+
 	// path keeps internal state about the current path
 	path []string
 }
@@ -63,6 +65,8 @@ func (fltr fieldSpecFilter) field(obj *yaml.RNode) error {
 
 	// lookup the field matching the next path element
 	var lookupField yaml.Filter
+	var kind yaml.Kind
+	var tag string
 	switch {
 	case !fltr.FieldSpec.CreateIfNotPresent || fltr.CreateKind == 0 || isSeq:
 		// dont' create the field if we don't find it
@@ -70,9 +74,13 @@ func (fltr fieldSpecFilter) field(obj *yaml.RNode) error {
 	case len(fltr.path) <= 1:
 		// create the field if it is missing: use the provided node kind
 		lookupField = yaml.LookupCreate(fltr.CreateKind, fieldName)
+		kind = fltr.CreateKind
+		tag = fltr.CreateTag
 	default:
 		// create the field if it is missing: must be a mapping node
 		lookupField = yaml.LookupCreate(yaml.MappingNode, fieldName)
+		kind = yaml.MappingNode
+		tag = "!!map"
 	}
 
 	// locate (or maybe create) the field
@@ -81,6 +89,13 @@ func (fltr fieldSpecFilter) field(obj *yaml.RNode) error {
 		return errors.WrapPrefixf(err, "fieldName: %s", fieldName)
 	}
 
+	// if the value exists, but is null, then change it to the creation type
+	// TODO: update yaml.LookupCreate to support this
+	if field.YNode().Tag == "!!null" {
+		field.YNode().Kind = kind
+		field.YNode().Tag = tag
+	}
+
 	// copy the current fltr and change the path on the copy
 	var next = fltr
 	// call filter for the next path element on the matching field

api/filters/fsslice/fsslice.go

@@ -49,6 +49,9 @@ type Filter struct {
 
 	// CreateKind is used to create fields that do not exist
 	CreateKind yaml.Kind
+
+	// CreateTag is used to set the tag if encountering a null field
+	CreateTag string
 }
 
 func (fltr Filter) Filter(obj *yaml.RNode) (*yaml.RNode, error) {
@@ -60,6 +63,7 @@ func (fltr Filter) Filter(obj *yaml.RNode) (*yaml.RNode, error) {
 			FieldSpec:  fltr.FsSlice[i],
 			SetValue:   fltr.SetValue,
 			CreateKind: fltr.CreateKind,
+			CreateTag:  fltr.CreateTag,
 		}).Filter(obj)
 		if err != nil {
 			return nil, err

api/filters/labels/labels.go

@@ -33,6 +33,7 @@ func (f Filter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
 					FsSlice:    f.FsSlice,
 					SetValue:   fsslice.SetEntry(k, f.Labels[k], yaml.StringTag),
 					CreateKind: yaml.MappingNode, // Labels are MappingNodes.
+					CreateTag:  "!!map",
 				}); err != nil {
 					return nil, err
 				}

api/filters/labels/labels_test.go

@@ -370,6 +370,35 @@ metadata:
 				},
 			},
 		},
+
+		"null_labels": {
+			input: `
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+  labels: null
+`,
+			expectedOutput: `
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+  labels:
+    a: a1
+`,
+			filter: Filter{
+				Labels: labelMap{
+					"a": "a1",
+				},
+				FsSlice: []types.FieldSpec{
+					{
+						Path:               "metadata/labels",
+						CreateIfNotPresent: true,
+					},
+				},
+			},
+		},
 	}
 
 	for tn, tc := range testCases {

api/filters/namespace/namespace.go

@@ -44,6 +44,7 @@ func (ns Filter) run(node *yaml.RNode) (*yaml.RNode, error) {
 		FsSlice:    ns.FsSlice,
 		SetValue:   fsslice.SetScalar(ns.Namespace),
 		CreateKind: yaml.ScalarNode, // Namespace is a ScalarNode
+		CreateTag:  yaml.StringTag,
 	})
 	return node, err
 }

api/filters/namespace/namespace_test.go

@@ -44,6 +44,37 @@ metadata:
 		filter: namespace.Filter{Namespace: "foo"},
 	},
 
+	{
+		name: "null_ns",
+		input: `
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+  namespace: null
+---
+apiVersion: example.com/v1
+kind: Bar
+metadata:
+  name: instance
+  namespace: null
+`,
+		expected: `
+apiVersion: example.com/v1
+kind: Foo
+metadata:
+  name: instance
+  namespace: foo
+---
+apiVersion: example.com/v1
+kind: Bar
+metadata:
+  name: instance
+  namespace: foo
+`,
+		filter: namespace.Filter{Namespace: "foo"},
+	},
+
 	{
 		name: "add-recurse",
 		input: `

api/filters/prefixsuffix/prefixsuffix.go

@@ -33,6 +33,7 @@ func (ns Filter) run(node *yaml.RNode) (*yaml.RNode, error) {
 		FsSlice:    ns.FsSlice,
 		SetValue:   ns.set,
 		CreateKind: yaml.ScalarNode, // Name is a ScalarNode
+		CreateTag:  yaml.StringTag,
 	})
 	return node, err
 }

api/filters/replicacount/replicacount.go

@@ -39,6 +39,7 @@ func (rc Filter) run(node *yaml.RNode) (*yaml.RNode, error) {
 		FsSlice:    rc.FsSlice,
 		SetValue:   rc.set,
 		CreateKind: yaml.ScalarNode, // replicas is a ScalarNode
+		CreateTag:  yaml.IntTag,
 	})
 	return node, err
 }

api/filters/replicacount/replicacount_test.go

@@ -61,6 +61,41 @@ spec:
 			expected: `
 apiVersion: custom/v1
 kind: Custom
+metadata:
+  name: cus
+spec:
+  template:
+    other: something
+    replicas: 42
+`,
+			filter: Filter{
+				Replica: types.Replica{
+					Name:  "cus",
+					Count: 42,
+				},
+			},
+			fsslice: types.FsSlice{
+				{
+					Path:               "spec/template/replicas",
+					CreateIfNotPresent: true,
+				},
+			},
+		},
+
+		"add_field_null": {
+			input: `
+apiVersion: custom/v1
+kind: Custom
+metadata:
+  name: cus
+spec:
+  template:
+    other: something
+    replicas: null
+`,
+			expected: `
+apiVersion: custom/v1
+kind: Custom
 metadata:
   name: cus
 spec: