add goplugin for exec generators and transformers

pkg/plugins/builtin/executable.go

@@ -0,0 +1,72 @@
+// +build plugin
+
+package main
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/ghodss/yaml"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/pgmconfig"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+)
+
+type plugin struct {
+	name  string
+	input string
+	rf    *resmap.Factory
+}
+
+var KustomizePlugin plugin
+
+func (p *plugin) Config(
+	ldr ifc.Loader, rf *resmap.Factory, k ifc.Kunstructured) error {
+	dir := filepath.Join(pgmconfig.ConfigRoot(), "plugins")
+	id := k.GetGvk()
+	p.name = filepath.Join(dir, id.Group, id.Version, id.Kind)
+	content, err := yaml.Marshal(k)
+	if err != nil {
+		return err
+	}
+	p.input = string(content)
+	p.rf = rf
+	return nil
+}
+
+func (p *plugin) Generate() (resmap.ResMap, error) {
+	return p.run(nil)
+}
+
+func (p *plugin) Transformer(rm resmap.ResMap) error {
+	result, err := p.run(rm)
+	if err != nil {
+		return err
+	}
+	for id := range rm {
+		delete(rm, id)
+	}
+	for id, r := range result {
+		rm[id] = r
+	}
+	return nil
+}
+
+func (p *plugin) run(rm resmap.ResMap) (resmap.ResMap, error) {
+	cmd := exec.Command(p.name, p.input)
+	cmd.Env = os.Environ()
+	if rm != nil {
+		content, err := rm.EncodeAsYaml()
+		if err != nil {
+			return nil, err
+		}
+		cmd.Stdin = bytes.NewReader(content)
+	}
+	output, err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+	return p.rf.NewResMapFromBytes(output)
+}