Helm chart generator exec plugin

pkg/plugins/execplugin.go

@@ -0,0 +1,185 @@
+/*
+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"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/ghodss/yaml"
+	"sigs.k8s.io/kustomize/k8sdeps/kv/plugin"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/pgmconfig"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+)
+
+const (
+	ArgsOneLiner = "argsOneLiner"
+	ArgsFromFile = "argsFromFile"
+)
+
+// 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
+
+	// Optional command line arguments to the executable
+	// pulled from specially named fields in cfg.
+	// This is for executables that don't want to parse YAML.
+	args []string
+
+	// Plugin configuration data.
+	cfg []byte
+
+	// 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(), plugin.PluginRoot)
+	id := k.GetGvk()
+	p.name = filepath.Join(dir, id.Group, id.Version, id.Kind)
+	p.rf = rf
+	p.ldr = ldr
+
+	var err error
+	p.cfg, err = yaml.Marshal(k)
+	if err != nil {
+		return err
+	}
+	err = p.processOptionalArgsFields(k)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (p *ExecPlugin) processOptionalArgsFields(k ifc.Kunstructured) error {
+	args, err := k.GetFieldValue(ArgsOneLiner)
+	if err == nil && args != "" {
+		p.args = strings.Split(args, " ")
+	}
+	fileName, err := k.GetFieldValue(ArgsFromFile)
+	if err == nil && fileName != "" {
+		content, err := p.ldr.Load(fileName)
+		if err != nil {
+			return err
+		}
+		for _, x := range strings.Split(string(content), "\n") {
+			x := strings.TrimLeft(x, " ")
+			if x != "" {
+				p.args = append(p.args, x)
+			}
+		}
+	}
+	return nil
+}
+
+func (p *ExecPlugin) writeConfig() (string, error) {
+	tmpFile, err := ioutil.TempFile("", "kust-pipe")
+	if err != nil {
+		return "", err
+	}
+	syscall.Mkfifo(tmpFile.Name(), 0600)
+	stdout, err := os.OpenFile(tmpFile.Name(), os.O_RDWR, 0600)
+	if err != nil {
+		return "", err
+	}
+	_, err = stdout.Write(p.cfg)
+	if err != nil {
+		return "", err
+	}
+	err = stdout.Close()
+	if err != nil {
+		return "", err
+	}
+	return tmpFile.Name(), 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 = p.getEnv()
+	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 = p.getEnv()
+		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
+}
+
+// The first arg is always the absolute path to a temporary file
+// holding the YAML form of the plugin config.
+func (p *ExecPlugin) getArgs() ([]string, error) {
+	configFileName, err := p.writeConfig()
+	if err != nil {
+		return nil, err
+	}
+	return append([]string{configFileName}, p.args...), nil
+}
+
+func (p *ExecPlugin) getEnv() []string {
+	env := os.Environ()
+	env = append(env, "KUSTOMIZE_PLUGIN_CONFIG_STRING="+string(p.cfg))
+	return env
+}