kptdev · kispaljr · Sep 18, 2025
@@ -53,6 +53,7 @@ const (
 
 	// UnknownNamespace is the special char for cluster-scoped or unknown-scoped resources. This is only used in upstream-identifier
 	UnknownNamespace = "~C"
+
 	// DefaultNamespace is the actual namespace value if a namespace-scoped resource has its namespace field unspecified.
 	DefaultNamespace = "default"
 )

@@ -5,18 +5,18 @@ go 1.24.3
 require (
 	github.com/go-errors/errors v1.5.1
 	github.com/google/go-cmp v0.7.0
+	github.com/kptdev/kpt v1.0.0-beta.57.0.20250625181933-26ae79c92ed2
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/stretchr/testify v1.10.0
+	gotest.tools v2.2.0+incompatible
 	k8s.io/apimachinery v0.33.1
 	// We must not include any core k8s APIs (e.g. k8s.io/api) in
 	// the dependencies, depending on them will likely to cause version skew for
 	// consumers. The dependencies for tests and examples should be isolated.
 	k8s.io/klog/v2 v2.130.1
 	sigs.k8s.io/kustomize/kyaml v0.19.0
-
 )
 
-require github.com/kptdev/kpt v1.0.0-beta.57.0.20250625181933-26ae79c92ed2
-
 require (
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/go-logr/logr v1.4.2 // indirect

@@ -32,6 +32,8 @@ github.com/mailru/easyjson v0.9.0 h1:PrnmzHw7262yW8sTBwxi1PdJA3Iw/EKBa8psRf7d9a4
 github.com/mailru/easyjson v0.9.0/go.mod h1:1+xMtQp2MRNVL/V1bOzuP3aP8VNwRW55fQUto+XFtTU=
 github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00 h1:n6/2gBQ3RWajuToeY6ZtZTIKv2v7ThUy5KKusIT0yc0=
 github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00/go.mod h1:Pm3mSP3c5uWn86xMLZ5Sa7JB9GsEZySvHYXCTK4E9q4=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
@@ -82,6 +84,8 @@ gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EV
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gotest.tools v2.2.0+incompatible h1:VsBPFP1AI068pPrMxtb/S8Zkgf9xEmTLJjfM+P5UIEo=
+gotest.tools v2.2.0+incompatible/go.mod h1:DsYFclhRJ6vuDpmuTbkuFWG+y2sxOXAzmJt81HFBacw=
 k8s.io/apimachinery v0.33.1 h1:mzqXWV8tW9Rw4VeW9rEkqvnxj59k1ezDUl20tFK/oM4=
 k8s.io/apimachinery v0.33.1/go.mod h1:BHW0YOu7n22fFv/JkYOEfkUYNRN0fj0BlvMFWA7b+SM=
 k8s.io/klog/v2 v2.130.1 h1:n9Xl7H1Xvksem4KFG4PYbdQCQxqc/tTUyrgXaOhHSzk=

@@ -46,14 +46,23 @@ type MapVariant struct {
 	node *yaml.Node
 }
 
-func (o *MapVariant) GetKind() variantKind {
-	return variantKindMap
+func (o *MapVariant) GetKind() VariantKind {
+	return VariantKindMap
 }
 
 func (o *MapVariant) Node() *yaml.Node {
 	return o.node
 }
 
+func (o *MapVariant) IsEmpty() bool {
+	return o == nil || o.node == nil || len(o.node.Content) == 0
+}
+
+func (o *MapVariant) HasKey(key string) bool {
+	_, found := o.getVariant(key)
+	return found
+}
+
 func (o *MapVariant) Entries() (map[string]variant, error) {
 	entries := make(map[string]variant)
 
@@ -85,13 +94,6 @@ func (o *MapVariant) Entries() (map[string]variant, error) {
 	return entries, nil
 }
 
-func asString(node *yaml.Node) (string, bool) {
-	if node.Kind == yaml.ScalarNode && (node.Tag == "!!str" || node.Tag == "") {
-		return node.Value, true
-	}
-	return "", false
-}
-
 func (o *MapVariant) getVariant(key string) (variant, bool) {
 	valueNode, found := getValueNode(o.node, key)
 	if !found {
@@ -102,58 +104,31 @@ func (o *MapVariant) getVariant(key string) (variant, bool) {
 	return v, true
 }
 
-func getValueNode(m *yaml.Node, key string) (*yaml.Node, bool) {
-	children := m.Content
-	if len(children)%2 != 0 {
-		log.Fatalf("unexpected number of children for map %d", len(children))
-	}
-
-	for i := 0; i < len(children); i += 2 {
-		keyNode := children[i]
-
-		k, ok := asString(keyNode)
-		if ok && k == key {
-			valueNode := children[i+1]
-			return valueNode, true
-		}
+func (o *MapVariant) setField(key string, val variant) {
+	newNode := val.Node()
+	i := findMapKey(o.node, key)
+	if i >= 0 {
+		// update existing field
+		deepCopyFormatting(o.node.Content[i+1], newNode)
+		o.node.Content[i+1] = newNode
+	} else {
+		// insert new field at the end
+		o.node.Content = append(o.node.Content, buildStringNode(key), newNode)
 	}
-	return nil, false
 }
 
-func (o *MapVariant) set(key string, val variant) {
-	o.setYAMLNode(key, val.Node())
+func (o *MapVariant) Set(newValue *MapVariant) {
+	newNode := newValue.Node()
+	deepCopyFormatting(o.node, newNode)
+	o.node.Content = newNode.Content
 }
 
-func (o *MapVariant) setYAMLNode(key string, node *yaml.Node) {
-	children := o.node.Content
-	if len(children)%2 != 0 {
-		log.Fatalf("unexpected number of children for map %d", len(children))
-	}
-
-	for i := 0; i < len(children); i += 2 {
-		keyNode := children[i]
-
-		k, ok := asString(keyNode)
-		if ok && k == key {
-			// TODO: Copy comments?
-			oldNode := children[i+1]
-			children[i+1] = node
-			children[i+1].FootComment = oldNode.FootComment
-			children[i+1].HeadComment = oldNode.HeadComment
-			children[i+1].LineComment = oldNode.LineComment
-			return
-		}
-	}
-
-	o.node.Content = append(o.node.Content, buildStringNode(key), node)
-}
-
-func (o *MapVariant) remove(key string) (bool, error) {
+func (o *MapVariant) remove(key string) bool {
 	removed := false
 
 	children := o.node.Content
 	if len(children)%2 != 0 {
-		return false, fmt.Errorf("unexpected number of children for map %d", len(children))
+		log.Fatalf("couldn't remove field %q from map node: unexpected odd number of children (%d)", key, len(children))
 	}
 
 	var keep []*yaml.Node
@@ -171,7 +146,7 @@ func (o *MapVariant) remove(key string) (bool, error) {
 
 	o.node.Content = keep
 
-	return removed, nil
+	return removed
 }
 
 // remove field metadata.creationTimestamp when it's null.
@@ -275,11 +250,26 @@ func (nodes yamlKeyValuePairs) Swap(i, j int) { nodes[i], nodes[j] = nodes[j], n
 // otherwise it will insert a map at the specified field.
 // Note that if the value exists but is not a map, it will be replaced with a map.
 func (o *MapVariant) UpsertMap(field string) *MapVariant {
-	m := o.GetMap(field)
-	if m != nil {
-		return m
+	node, found := o.getVariant(field)
+
+	if found {
+		switch node := node.(type) {
+		case *MapVariant:
+			// field was found and it is a map
+			if !node.IsEmpty() {
+				return node
+			}
+			// if the map is empty, replace it with a new map
+			// this supposed to result in better formatting if the map value is specified as {}
+			_ = o.remove(field)
+
+		default:
+			// field was found and it is NOT a map
+			_ = o.remove(field)
+		}
 	}
 
+	// insert map at field
 	keyNode := &yaml.Node{
 		Kind:  yaml.ScalarNode,
 		Value: field,

@@ -57,7 +57,7 @@ func (o *MapVariant) SetNestedValue(val variant, fields ...string) error {
 	var err error
 	for i := 0; i < n; i++ {
 		if i == n-1 {
-			current.set(fields[i], val)
+			current.setField(fields[i], val)
 		} else {
 			current, _, err = current.getMap(fields[i], true)
 			if err != nil {
@@ -180,19 +180,19 @@ func (o *MapVariant) SetNestedFloat(f float64, fields ...string) error {
 	return o.SetNestedValue(newFloatScalarVariant(f), fields...)
 }
 
-func (o *MapVariant) GetNestedSlice(fields ...string) (*sliceVariant, bool, error) {
+func (o *MapVariant) GetNestedSlice(fields ...string) (*SliceVariant, bool, error) {
 	node, found, err := o.GetNestedValue(fields...)
 	if err != nil || !found {
 		return nil, found, err
 	}
-	nodeS, ok := node.(*sliceVariant)
+	nodeS, ok := node.(*SliceVariant)
 	if !ok {
 		return nil, found, fmt.Errorf("incorrect type, was %T", node)
 	}
 	return nodeS, found, err
 }
 
-func (o *MapVariant) SetNestedSlice(s *sliceVariant, fields ...string) error {
+func (o *MapVariant) SetNestedSlice(s *SliceVariant, fields ...string) error {
 	return o.SetNestedValue(s, fields...)
 }
 
@@ -206,13 +206,13 @@ func (o *MapVariant) RemoveNestedField(fields ...string) (bool, error) {
 		}
 
 		if i == n-1 {
-			return current.remove(fields[i])
+			return current.remove(fields[i]), nil
 		}
 		switch entry := entry.(type) {
 		case *MapVariant:
 			current = entry
 		default:
-			return false, fmt.Errorf("value is of unexpected type %T", entry)
+			return false, fmt.Errorf("removeNestedField: value is expected to be map, but is of unexpected type %T", entry)
 		}
 	}
 	return false, fmt.Errorf("unexpected code reached")

@@ -32,8 +32,8 @@ type scalarVariant struct {
 	node *yaml.Node
 }
 
-func (v *scalarVariant) GetKind() variantKind {
-	return variantKindScalar
+func (v *scalarVariant) GetKind() VariantKind {
+	return VariantKindScalar
 }
 
 func newStringScalarVariant(s string) *scalarVariant {

@@ -18,34 +18,34 @@ import (
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
-type sliceVariant struct {
+type SliceVariant struct {
 	node *yaml.Node
 }
 
-func NewSliceVariant(s ...variant) *sliceVariant {
+func NewSliceVariant(s ...variant) *SliceVariant {
 	node := buildSequenceNode()
 	for _, v := range s {
 		node.Content = append(node.Content, v.Node())
 	}
-	return &sliceVariant{node: node}
+	return &SliceVariant{node: node}
 }
 
-func (v *sliceVariant) GetKind() variantKind {
-	return variantKindSlice
+func (v *SliceVariant) GetKind() VariantKind {
+	return VariantKindSlice
 }
 
-func (v *sliceVariant) Node() *yaml.Node {
+func (v *SliceVariant) Node() *yaml.Node {
 	return v.node
 }
 
-func (v *sliceVariant) Clear() {
+func (v *SliceVariant) Clear() {
 	v.node.Content = nil
 }
 
-func (v *sliceVariant) Elements() ([]*MapVariant, error) {
+func (v *SliceVariant) Elements() ([]*MapVariant, error) {
 	return ExtractObjects(v.node.Content...)
 }
 
-func (v *sliceVariant) Add(node variant) {
+func (v *SliceVariant) Add(node variant) {
 	v.node.Content = append(v.node.Content, node.Node())
 }
@@ -23,16 +23,16 @@ import (
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
-type variantKind string
+type VariantKind string
 
 const (
-	variantKindMap    variantKind = "Map"
-	variantKindSlice  variantKind = "Slice"
-	variantKindScalar variantKind = "Scalar"
+	VariantKindMap    VariantKind = "Map"
+	VariantKindSlice  VariantKind = "Slice"
+	VariantKindScalar VariantKind = "Scalar"
 )
 
 type variant interface {
-	GetKind() variantKind
+	GetKind() VariantKind
 	Node() *yaml.Node
 }
 
@@ -90,7 +90,7 @@ func toVariant(n *yaml.Node) variant {
 	case yaml.MappingNode:
 		return &MapVariant{node: n}
 	case yaml.SequenceNode:
-		return &sliceVariant{node: n}
+		return &SliceVariant{node: n}
 
 	default:
 		panic("unhandled yaml node kind")
@@ -150,7 +150,7 @@ func TypedObjectToMapVariant(v interface{}) (*MapVariant, error) {
 	return mv, err
 }
 
-func TypedObjectToSliceVariant(v interface{}) (*sliceVariant, error) {
+func TypedObjectToSliceVariant(v interface{}) (*SliceVariant, error) {
 	// The built-in types only have json tags. We can't simply do ynode.Encode(v),
 	// since it use the lowercased field name by default if no yaml tag is specified.
 	// This affects both k8s built-in types (e.g. appsv1.Deployment) and any types
@@ -177,7 +177,7 @@ func TypedObjectToSliceVariant(v interface{}) (*sliceVariant, error) {
 		return nil, fmt.Errorf("unable to convert strong typed object to yaml node: %w", err)
 	}
 
-	return &sliceVariant{node: node}, nil
+	return &SliceVariant{node: node}, nil
 }
 
 func MapVariantToTypedObject(mv *MapVariant, ptr interface{}) error {