add support for exec plugins

pkg/plugins/executable.go

@@ -0,0 +1,140 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package plugins
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sigs.k8s.io/kustomize/pkg/types"
+	"strings"
+
+	"github.com/ghodss/yaml"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/pgmconfig"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+)
+
+// ExecPlugin record the name and args of an executable
+// It triggers the executable generator and transformer
+type ExecPlugin struct {
+	// name of the executable
+	name string
+
+	// one line of arguments for the executable
+	argOneLiner string
+
+	// relative file path to a file
+	// Each line of this file is treated as one argument
+	argsFromFile string
+
+	// resmap Factory to make resources
+	rf *resmap.Factory
+
+	// loader to load files
+	ldr ifc.Loader
+}
+
+func (p *ExecPlugin) 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)
+	p.rf = rf
+	p.ldr = ldr
+
+	var err error
+	p.argOneLiner, err = k.GetFieldValue("arg")
+	if err != nil && !isNoFieldError(err) {
+		return err
+	}
+	p.argsFromFile, err = k.GetFieldValue("file")
+	if err != nil && !isNoFieldError(err) {
+		return err
+	}
+	return nil
+}
+
+func (p *ExecPlugin) Generate() (resmap.ResMap, error) {
+	args, err := p.getArgs()
+	if err != nil {
+		return nil, err
+	}
+	cmd := exec.Command(p.name, args...)
+	cmd.Env = os.Environ()
+	cmd.Stderr = os.Stderr
+	output, err := cmd.Output()
+	if err != nil {
+		return nil, err
+	}
+	return p.rf.NewResMapFromBytes(output)
+}
+
+func (p *ExecPlugin) Transform(rm resmap.ResMap) error {
+	args, err := p.getArgs()
+	if err != nil {
+		return err
+	}
+
+	for id, r := range rm {
+		content, err := yaml.Marshal(r.Kunstructured)
+		if err != nil {
+			return err
+		}
+		cmd := exec.Command(p.name, args...)
+		cmd.Env = os.Environ()
+		cmd.Stdin = bytes.NewReader(content)
+		cmd.Stderr = os.Stderr
+		output, err := cmd.Output()
+		if err != nil {
+			return err
+		}
+		tmpMap, err := p.rf.NewResMapFromBytes(output)
+		if err != nil {
+			return err
+		}
+		if len(tmpMap) != 1 {
+			return fmt.Errorf("Unable to put two resources into one")
+		}
+		for _, v := range tmpMap {
+			rm[id].Kunstructured = v.Kunstructured
+		}
+	}
+	return nil
+}
+
+func (p *ExecPlugin) getArgs() ([]string, error) {
+	args := strings.Split(p.argOneLiner, " ")
+	if p.argsFromFile != "" {
+		content, err := p.ldr.Load(p.argsFromFile)
+		if err != nil {
+			return nil, err
+		}
+		args = append(args, strings.Split(string(content), "\n")...)
+	}
+	return args, nil
+}
+
+func isNoFieldError(e error) bool {
+	_, ok := e.(types.NoFieldError)
+	if ok {
+		return true
+	}
+	return false
+}