move strategic merge patch transformer to a builtin transformer

plugin/builtin/patchstrategicmergetransformer/PatchStrategicMergeTransformer.go

@@ -0,0 +1,76 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+//go:generate go run sigs.k8s.io/kustomize/v3/cmd/pluginator
+package main
+
+import (
+	"fmt"
+	"sigs.k8s.io/kustomize/v3/pkg/ifc"
+	"sigs.k8s.io/kustomize/v3/pkg/resmap"
+	"sigs.k8s.io/kustomize/v3/pkg/resource"
+	"sigs.k8s.io/kustomize/v3/pkg/types"
+	"sigs.k8s.io/yaml"
+)
+
+type plugin struct {
+	ldr           ifc.Loader
+	rf            *resmap.Factory
+	loadedPatches []*resource.Resource
+	Paths         []types.PatchStrategicMerge `json:"paths,omitempty" yaml:"paths,omitempty"`
+	Patches       string                      `json:patches,omitempty" yaml:"patches,omitempty"`
+}
+
+//noinspection GoUnusedGlobalVariable
+var KustomizePlugin plugin
+
+func (p *plugin) Config(
+	ldr ifc.Loader, rf *resmap.Factory, c []byte) (err error) {
+	p.ldr = ldr
+	p.rf = rf
+	err = yaml.Unmarshal(c, p)
+	if err != nil {
+		return err
+	}
+	if len(p.Paths) == 0 && p.Patches == "" {
+		return fmt.Errorf("empty file path and empty patch content")
+	}
+	if len(p.Paths) != 0 {
+		res, err := p.rf.RF().SliceFromPatches(ldr, p.Paths)
+		if err != nil {
+			return err
+		}
+		p.loadedPatches = res
+	}
+	if p.Patches != "" {
+		res, err := p.rf.RF().SliceFromBytes([]byte(p.Patches))
+		if err != nil {
+			return err
+		}
+		p.loadedPatches = append(p.loadedPatches, res...)
+	}
+
+	if len(p.loadedPatches) == 0 {
+		return fmt.Errorf(
+			"patch appears to be empty; files=%v, Patch=%s", p.Paths, p.Patches)
+	}
+	return err
+}
+
+func (p *plugin) Transform(m resmap.ResMap) error {
+	patches, err := p.rf.MergePatches(p.loadedPatches)
+	if err != nil {
+		return err
+	}
+	for _, patch := range patches.Resources() {
+		target, err := m.GetById(patch.OrgId())
+		if err != nil {
+			return err
+		}
+		err = target.Patch(patch.Kunstructured)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}