fix(plugins): handle nil intermediate values in JSON path traversal

Uses go-openapi/jsonpointer@v0.21.2 fix to improve handling of intermediate nil values.

Signed-off-by: Matthew F Leader <mleader@redhat.com>

Author: mfleader

go.mod

@@ -4,10 +4,10 @@ go 1.23.0
 
 require (
 	github.com/go-logr/logr v1.4.1
+	github.com/go-openapi/jsonpointer v0.21.2
 	github.com/google/go-cmp v0.7.0
-	github.com/onsi/ginkgo/v2 v2.17.1
-	github.com/onsi/gomega v1.32.0
 	github.com/stretchr/testify v1.10.0
+	go.uber.org/zap v1.26.0
 	gopkg.in/yaml.v2 v2.4.0
 	gopkg.in/yaml.v3 v3.0.1
 	k8s.io/api v0.29.2
@@ -31,10 +31,8 @@ require (
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/go-errors/errors v1.4.2 // indirect
 	github.com/go-logr/zapr v1.3.0 // indirect
-	github.com/go-openapi/jsonpointer v0.21.1 // indirect
 	github.com/go-openapi/jsonreference v0.21.0 // indirect
 	github.com/go-openapi/swag v0.23.1 // indirect
-	github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
@@ -52,6 +50,8 @@ require (
 	github.com/modern-go/reflect2 v1.0.2 // indirect
 	github.com/monochromegane/go-gitignore v0.0.0-20200626010858-205db1a8cc00 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/onsi/ginkgo/v2 v2.17.1 // indirect
+	github.com/onsi/gomega v1.32.0 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/client_golang v1.18.0 // indirect
@@ -61,15 +61,13 @@ require (
 	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/xlab/treeprint v1.2.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
-	go.uber.org/zap v1.26.0 // indirect
 	golang.org/x/exp v0.0.0-20250506013437-ce4c2cf36ca6 // indirect
 	golang.org/x/net v0.40.0 // indirect
 	golang.org/x/oauth2 v0.30.0 // indirect
 	golang.org/x/sys v0.33.0 // indirect
 	golang.org/x/term v0.32.0 // indirect
 	golang.org/x/text v0.25.0 // indirect
 	golang.org/x/time v0.11.0 // indirect
-	golang.org/x/tools v0.33.0 // indirect
 	gomodules.xyz/jsonpatch/v2 v2.5.0 // indirect
 	google.golang.org/protobuf v1.36.6 // indirect
 	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect

go.sum

@@ -23,8 +23,8 @@ github.com/go-logr/logr v1.4.1 h1:pKouT5E8xu9zeFC39JXRDukb6JFQPXM5p5I91188VAQ=
 github.com/go-logr/logr v1.4.1/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/zapr v1.3.0 h1:XGdV8XW8zdwFiwOA2Dryh1gj2KRQyOOoNmBy4EplIcQ=
 github.com/go-logr/zapr v1.3.0/go.mod h1:YKepepNBd1u/oyhd/yQmtjVXmm9uML4IXUgMOwR8/Gg=
-github.com/go-openapi/jsonpointer v0.21.1 h1:whnzv/pNXtK2FbX/W9yJfRmE2gsmkfahjMKB0fZvcic=
-github.com/go-openapi/jsonpointer v0.21.1/go.mod h1:50I1STOfbY1ycR8jGz8DaMeLCdXiI6aDteEdRNNzpdk=
+github.com/go-openapi/jsonpointer v0.21.2 h1:AqQaNADVwq/VnkCmQg6ogE+M3FOsKTytwges0JdwVuA=
+github.com/go-openapi/jsonpointer v0.21.2/go.mod h1:50I1STOfbY1ycR8jGz8DaMeLCdXiI6aDteEdRNNzpdk=
 github.com/go-openapi/jsonreference v0.21.0 h1:Rs+Y7hSXT83Jacb7kFyjn4ijOuVGSvOdF2+tg1TRrwQ=
 github.com/go-openapi/jsonreference v0.21.0/go.mod h1:LmZmgsrTkVg9LG4EaHeY8cBDslNPMo06cago5JNLkm4=
 github.com/go-openapi/swag v0.23.1 h1:lpsStH0n2ittzTnbaSloVZLuB5+fvSY/+hnagBjSNZU=
@@ -103,7 +103,6 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
 github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
 github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
-github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=

pkg/deploy/plugins/field_mutator.go

@@ -1,6 +1,7 @@
 package plugins
 
 import (
+	"encoding/json"
 	"fmt"
 	"strings"
 
@@ -126,53 +127,60 @@ func setTargetField(res *resource.Resource, value any, mapping FieldMapping) err
 }
 
 func setWithPathCreation(data any, ptr jsonpointer.Pointer, value any) (any, error) {
-	// try setting value if the path already exists
-	if updatedData, err := ptr.Set(data, value); err == nil {
-		return updatedData, nil
+	// try direct set first
+	if result, err := ptr.Set(data, value); err == nil {
+		return result, nil
 	}
 
-	// otherwise, we need to create the path first
+	// create missing path structure
 	tokens := ptr.DecodedTokens()
 	if len(tokens) == 0 {
 		return value, nil
 	}
-	result := data
 
-	// JSON Pointer Set() fails if intermediate paths don't exist, so we must
-	// build the path incrementally from root to target, creating missing containers
-	for i := 1; i <= len(tokens)-1; i++ {
-		partialPath := "/" + strings.Join(tokens[:i], "/")
-		partialPtr, err := jsonpointer.New(partialPath)
-		if err != nil {
-			return nil, fmt.Errorf("failed to create partial pointer: %w", err)
+	result := deepCopyData(data)
+
+	// create each missing parent container
+	for i := 0; i < len(tokens)-1; i++ {
+		parentPath := "/" + strings.Join(tokens[:i+1], "/")
+		parentPtr, _ := jsonpointer.New(parentPath)
+
+		// skip if parent already exists and is not nil
+		if parent, _, err := parentPtr.Get(result); err == nil && parent != nil {
+			continue
 		}
-		// Get() is used as existence test - error means path doesn't exist and needs creation
-		_, _, err = partialPtr.Get(result)
-		if err != nil {
-			nextToken := tokens[i]
-			var newContainer any
-			// create array if next token is numeric (e.g., "/ports/0")
-			if isNumericString(nextToken) {
-				newContainer = make([]any, 0)
-			} else {
-				// create map otherwise (e.g., "/spec/strategy")
-				newContainer = make(map[string]any)
-			}
 
-			// create the missing path segment
-			result, err = partialPtr.Set(result, newContainer)
-			if err != nil {
-				return nil, fmt.Errorf("failed to create intermediate path %q: %w", partialPath, err)
-			}
+		// create container based on next token type
+		var container any
+		if isNumericString(tokens[i+1]) {
+			container = make([]any, 0)
+		} else {
+			container = make(map[string]any)
+		}
+
+		// set the container (jsonpointer handles the rest)
+		var err error
+		if result, err = parentPtr.Set(result, container); err != nil {
+			return nil, fmt.Errorf("failed to create path at %q: %w", parentPath, err)
 		}
 	}
 
-	result, err := ptr.Set(result, value)
+	// final set should now succeed
+	return ptr.Set(result, value)
+}
+
+// deepCopyData creates a deep copy of the data structure using JSON marshal/unmarshal.
+func deepCopyData(data any) any {
+	jsonBytes, err := json.Marshal(data)
 	if err != nil {
-		return nil, fmt.Errorf("failed to set final value: %w", err)
+		return data // fallback to original if copy fails
 	}
 
-	return result, nil
+	var result any
+	if err := json.Unmarshal(jsonBytes, &result); err != nil {
+		return data // fallback to original if copy fails
+	}
+	return result
 }
 
 func updateResource(res *resource.Resource, updatedData any) error {

pkg/deploy/plugins/field_mutator_test.go

@@ -293,3 +293,60 @@ func TestTransform(t *testing.T) {
 		})
 	}
 }
+
+// TestJsonPointerNilTraversalPanic reproduces the panic when jsonpointer encounters nil intermediate values.
+func TestJsonPointerNilTraversalPanic(t *testing.T) {
+	t.Run("panic when traversing through nil intermediate value", func(t *testing.T) {
+		// create a data structure with nil intermediate value that causes jsonpointer to panic
+		testData := map[string]any{
+			"apiVersion": "v1",
+			"kind":       "TestResource",
+			"metadata": map[string]any{
+				"name": "test-resource",
+			},
+			"spec": map[string]any{
+				"container": map[string]any{
+					"properties": nil, // this nil causes the panic when traversed
+				},
+			},
+		}
+
+		rf := resource.NewFactory(nil)
+		res, err := rf.FromMap(testData)
+		require.NoError(t, err)
+
+		resMap := resmap.New()
+		require.NoError(t, resMap.Append(res))
+
+		// field mapping that attempts to traverse through the nil intermediate value
+		transformer := CreateFieldMutator(FieldMutatorConfig{
+			Mappings: []FieldMapping{
+				{
+					SourceValue:       nil,
+					DefaultValue:      "test-value",
+					TargetField:       "/spec/container/properties/name", // this path goes through nil
+					TargetKind:        "TestResource",
+					CreateIfNotExists: true,
+				},
+			},
+		})
+
+		err = transformer.Transform(resMap)
+		require.NoError(t, err, "Transform should succeed after the fix")
+
+		// nil properties should be replaced with a proper map
+		updatedRes := resMap.GetByIndex(0)
+		resMap2, err := updatedRes.Map()
+		require.NoError(t, err)
+
+		spec, ok := resMap2["spec"].(map[string]any)
+		require.True(t, ok, "spec should be a map")
+		container, ok := spec["container"].(map[string]any)
+		require.True(t, ok, "container should be a map")
+		properties, ok := container["properties"].(map[string]any)
+		require.True(t, ok, "properties should be a map")
+
+		require.Equal(t, "test-value", properties["name"], "name should be set correctly")
+		require.NotNil(t, properties, "properties should no longer be nil")
+	})
+}