fix: support non-string values

pkg/rewriter/generated_test.go

@@ -1,6 +1,7 @@
 package rewriter
 
 import (
+	"encoding/json"
 	"fmt"
 	"testing"
 	"time"
@@ -41,7 +42,9 @@ func TestGeneratedValues(t *testing.T) {
 		fieldName := fmt.Sprintf("metadata.%s", k)
 		annotation := annotationForOriginalValue(fieldName)
 		assert.Contains(t, pod.GetAnnotations(), annotation, "annotation %q missing", fieldName)
-		assert.Equal(t, v, pod.GetAnnotations()[annotation], "wrong value stored in %q", fieldName)
+		var unserialized any
+		assert.NoError(t, json.Unmarshal([]byte(pod.GetAnnotations()[annotation]), &unserialized))
+		assert.Equal(t, v, unserialized, "wrong value stored in %q", fieldName)
 	}
 
 	pod = testRewriterBeforeServing(t, r, pod)

pkg/rewriter/rewriter.go

@@ -1,6 +1,7 @@
 package rewriter
 
 import (
+	"encoding/json"
 	"fmt"
 	"strings"
 
@@ -41,7 +42,7 @@ func (r *removeField) annotationName() string {
 }
 
 func (r *removeField) BeforeImport(u *unstructured.Unstructured) error {
-	s, ok, err := unstructured.NestedString(u.Object, r.fieldPath...)
+	value, ok, err := unstructured.NestedFieldCopy(u.Object, r.fieldPath...)
 	if err != nil {
 		return err
 	}
@@ -51,7 +52,12 @@ func (r *removeField) BeforeImport(u *unstructured.Unstructured) error {
 	}
 
 	unstructured.RemoveNestedField(u.Object, r.fieldPath...)
-	return addAnnotation(u, r.annotationName(), s)
+	serialized, err := json.Marshal(value)
+	if err != nil {
+		return err
+	}
+
+	return addAnnotation(u, r.annotationName(), string(serialized))
 }
 
 func (r *removeField) BeforeServing(u *unstructured.Unstructured) error {
@@ -63,7 +69,12 @@ func (r *removeField) BeforeServing(u *unstructured.Unstructured) error {
 		return nil
 	}
 
-	if err := unstructured.SetNestedField(u.Object, value, r.fieldPath...); err != nil {
+	var unserialized any
+	if err := json.Unmarshal([]byte(value), &unserialized); err != nil {
+		return err
+	}
+
+	if err := unstructured.SetNestedField(u.Object, unserialized, r.fieldPath...); err != nil {
 		return err
 	}
 	unstructured.RemoveNestedField(u.Object, "metadata", "annotations", r.annotationName())

pkg/rewriter/rewriter_test.go

@@ -72,3 +72,17 @@ func TestRemoveField_SkipWithoutAnnotation(t *testing.T) {
 	pod = testRewriterBeforeServing(t, removeResourceVersion, pod)
 	assert.Equal(t, "1000", pod.GetResourceVersion())
 }
+
+func TestRemoveField_NilValue(t *testing.T) {
+	pod := &corev1.Pod{
+		ObjectMeta: metav1.ObjectMeta{},
+	}
+	assert.Empty(t, pod.GetCreationTimestamp())
+	removeCreationTimetstamp := RemoveField("metadata", "creationTimestamp")
+	pod = testRewriterBeforeImport(t, removeCreationTimetstamp, pod)
+	assert.Contains(t, pod.GetAnnotations(), annotationForOriginalValue("metadata.creationTimestamp"))
+	assert.Equal(t, pod.GetAnnotations()[annotationForOriginalValue("metadata.creationTimestamp")], "null")
+	pod = testRewriterBeforeServing(t, removeCreationTimetstamp, pod)
+	assert.Empty(t, pod.GetCreationTimestamp())
+	assert.NotContains(t, pod.GetAnnotations(), annotationForOriginalValue("metadata.creationTimestamp"))
+}