Utilities for working with map[string]interface{} + yaml.Node

kyaml/filtersutil/filtersutil.go

@@ -0,0 +1,83 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package filtersutil
+
+import (
+	"encoding/json"
+
+	"sigs.k8s.io/kustomize/kyaml/errors"
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// ApplyToJSON applies the filter to the json objects.
+//
+// ApplyToJSON marshals the objects into a slice of yaml.RNodes, runs
+// the filter on the slice, and then unmarshals the values back.
+//
+// The filter must not create or delete objects because the objects
+// are updated in place.
+func ApplyToJSON(filter kio.Filter, objs ...marshalerUnmarshaler) error {
+	var nodes []*yaml.RNode
+
+	// convert the json objects to rnodes
+	for i := range objs {
+		node, err := getRNode(objs[i])
+		if err != nil {
+			return err
+		}
+		nodes = append(nodes, node)
+	}
+
+	// apply the filter
+	nodes, err := filter.Filter(nodes)
+	if err != nil {
+		return err
+	}
+	if len(nodes) != len(objs) {
+		return errors.Errorf("filter cannot create or delete objects")
+	}
+
+	// convert the rnodes to json objects
+	for i := range nodes {
+		err = setRNode(objs[i], nodes[0])
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+type marshalerUnmarshaler interface {
+	json.Unmarshaler
+	json.Marshaler
+}
+
+// getRNode converts k into an RNode
+func getRNode(k json.Marshaler) (*yaml.RNode, error) {
+	j, err := k.MarshalJSON()
+	if err != nil {
+		return nil, err
+	}
+	return yaml.Parse(string(j))
+}
+
+// setRNode marshals node into k
+func setRNode(k json.Unmarshaler, node *yaml.RNode) error {
+	s, err := node.String()
+	if err != nil {
+		return err
+	}
+	m := map[string]interface{}{}
+	if err := yaml.Unmarshal([]byte(s), &m); err != nil {
+		return err
+	}
+
+	b, err := json.Marshal(m)
+	if err != nil {
+		return err
+	}
+	return k.UnmarshalJSON(b)
+}