kyaml: initial support for yaml and resource manipulation

kyaml/kio/byteio_writer.go

@@ -0,0 +1,122 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package kio
+
+import (
+	"io"
+
+	"sigs.k8s.io/kustomize/kyaml/kio/kioutil"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// Writer writes ResourceNodes to bytes.
+type ByteWriter struct {
+	// Writer is where ResourceNodes are encoded.
+	Writer io.Writer
+
+	// KeepReaderAnnotations if set will keep the Reader specific annotations when writing
+	// the Resources, otherwise they will be cleared.
+	KeepReaderAnnotations bool
+
+	// ClearAnnotations is a list of annotations to clear when writing the Resources.
+	ClearAnnotations []string
+
+	// Style is a style that is set on the Resource Node Document.
+	Style yaml.Style
+
+	// FunctionConfig is the function config for an ResourceList.  If non-nil
+	// wrap the results in an ResourceList.
+	FunctionConfig *yaml.RNode
+
+	// WrappingKind if set will cause ByteWriter to wrap the Resources in
+	// an 'items' field in this kind.  e.g. if WrappingKind is 'List',
+	// ByteWriter will wrap the Resources in a List .items field.
+	WrappingKind string
+
+	// WrappingApiVersion is the apiVersion for WrappingKind
+	WrappingApiVersion string
+
+	// Sort if set, will cause ByteWriter to sort the the nodes before writing them.
+	Sort bool
+}
+
+var _ Writer = ByteWriter{}
+
+func (w ByteWriter) Write(nodes []*yaml.RNode) error {
+	if w.Sort {
+		if err := kioutil.SortNodes(nodes); err != nil {
+			return err
+		}
+	}
+
+	encoder := yaml.NewEncoder(w.Writer)
+	defer encoder.Close()
+	for i := range nodes {
+
+		// clean resources by removing annotations set by the Reader
+		if !w.KeepReaderAnnotations {
+			_, err := nodes[i].Pipe(yaml.ClearAnnotation(kioutil.IndexAnnotation))
+			if err != nil {
+				return err
+			}
+		}
+		for _, a := range w.ClearAnnotations {
+			_, err := nodes[i].Pipe(yaml.ClearAnnotation(a))
+			if err != nil {
+				return err
+			}
+		}
+
+		// TODO(pwittrock): factor this into a a common module for pruning empty values
+		_, err := nodes[i].Pipe(yaml.Lookup("metadata"), yaml.FieldClearer{
+			Name: "annotations", IfEmpty: true})
+		if err != nil {
+			return err
+		}
+		_, err = nodes[i].Pipe(yaml.FieldClearer{Name: "metadata", IfEmpty: true})
+		if err != nil {
+			return err
+		}
+
+		if w.Style != 0 {
+			nodes[i].YNode().Style = w.Style
+		}
+	}
+
+	// don't wrap the elements
+	if w.WrappingKind == "" {
+		for i := range nodes {
+			err := encoder.Encode(nodes[i].Document())
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+	// wrap the elements in a list
+	items := &yaml.Node{Kind: yaml.SequenceNode}
+	list := &yaml.Node{
+		Kind:  yaml.MappingNode,
+		Style: w.Style,
+		Content: []*yaml.Node{
+			{Kind: yaml.ScalarNode, Value: "apiVersion"},
+			{Kind: yaml.ScalarNode, Value: w.WrappingApiVersion},
+			{Kind: yaml.ScalarNode, Value: "kind"},
+			{Kind: yaml.ScalarNode, Value: w.WrappingKind},
+			{Kind: yaml.ScalarNode, Value: "items"}, items,
+		}}
+	if w.FunctionConfig != nil {
+		list.Content = append(list.Content,
+			&yaml.Node{Kind: yaml.ScalarNode, Value: "functionConfig"},
+			w.FunctionConfig.YNode())
+	}
+	doc := &yaml.Node{
+		Kind:    yaml.DocumentNode,
+		Style:   yaml.FoldedStyle,
+		Content: []*yaml.Node{list}}
+	for i := range nodes {
+		items.Content = append(items.Content, nodes[i].YNode())
+	}
+	return encoder.Encode(doc)
+}