move files into internal

cmd/pluginator/internal/krmfunction/converter.go

@@ -0,0 +1,165 @@
+package krmfunction
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/rakyll/statik/fs"
+	// load embedded func wrapper
+	_ "sigs.k8s.io/kustomize/cmd/pluginator/v2/internal/krmfunction/funcwrapper"
+)
+
+// Converter is a converter to convert the
+// plugin file to KRM function
+type Converter struct {
+	// Path to the output directory
+	outputDir string
+	// Path to the input file
+	inputFile       string
+	wrapperFileName string
+	pluginFileName  string
+	goModFileName   string
+	dockerFileName  string
+}
+
+// NewConverter return a pointer to a new converter
+func NewConverter(outputDir, inputFile string) *Converter {
+	return &Converter{
+		outputDir:       outputDir,
+		inputFile:       inputFile,
+		wrapperFileName: "main.go",
+		pluginFileName:  "plugin.go",
+		goModFileName:   "go.mod",
+		dockerFileName:  "Dockerfile",
+	}
+}
+
+// Convert converts the input file to a executable
+// KRM function and writes to destination directory
+func (c *Converter) Convert() error {
+	// read and process executable wrapper
+	wrapper, err := c.readEmbeddedFile(c.wrapperFileName)
+	if err != nil {
+		return err
+	}
+	wrapper = c.prepareWrapper(wrapper)
+
+	if !strings.HasSuffix(c.inputFile, ".go") {
+		return fmt.Errorf("input file %s is not a Go file", c.inputFile)
+	}
+
+	// read and process plugin code
+	pluginCode, err := c.readDiskFile(c.inputFile)
+	if err != nil {
+		return err
+	}
+	_, c.pluginFileName = filepath.Split(c.inputFile)
+
+	// go.mod file
+	goMod, err := c.readEmbeddedFile(c.goModFileName + ".src")
+	if err != nil {
+		return err
+	}
+
+	// prepare destination directory
+	err = c.mkDstDir()
+	if err != nil {
+		return err
+	}
+
+	// write
+	return c.write(map[string]string{
+		c.wrapperFileName: wrapper,
+		c.pluginFileName:  pluginCode,
+		c.goModFileName:   goMod,
+		c.dockerFileName:  c.getDockerfile(),
+	})
+}
+
+func (c *Converter) getDockerfile() string {
+	return `FROM golang:1.13-stretch
+ENV CGO_ENABLED=0
+WORKDIR /go/src/
+COPY . .
+RUN go build -v -o /usr/local/bin/function ./
+FROM alpine:latest
+COPY --from=0 /usr/local/bin/function /usr/local/bin/function
+CMD ["function"]
+`
+}
+
+func (c *Converter) prepareWrapper(content string) string {
+	b := bytes.NewBufferString(content)
+	o := &bytes.Buffer{}
+	scanner := bufio.NewScanner(b)
+	for scanner.Scan() {
+		line := scanner.Text()
+		// Set the package name to main
+		if strings.TrimSpace(line) == "package funcwrappersrc" {
+			line = "package main"
+		}
+		// assign to plugin variable
+		if strings.TrimSpace(line) == "var plugin resmap.Configurable" {
+			line = line + `
+	// KustomizePlugin is a global variable defined in every plugin
+	plugin = &KustomizePlugin
+`
+		}
+		o.WriteString(line + "\n")
+	}
+	return o.String()
+}
+
+// readEmbeddedFile read the file from embedded files with filename
+// name. Return the file content if it's successful.
+func (c *Converter) readEmbeddedFile(name string) (string, error) {
+	statikFS, err := fs.New()
+	if err != nil {
+		return "", err
+	}
+	r, err := statikFS.Open("/" + name)
+	if err != nil {
+		return "", err
+	}
+	defer r.Close()
+	contents, err := ioutil.ReadAll(r)
+	if err != nil {
+		return "", err
+	}
+
+	return string(contents), nil
+}
+
+func (c *Converter) readDiskFile(path string) (string, error) {
+	f, err := ioutil.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	return string(f), nil
+}
+
+func (c *Converter) mkDstDir() error {
+	p := c.outputDir
+	f, err := os.Open(p)
+	if err == nil || f != nil {
+		return fmt.Errorf("directory %s has already existed", p)
+	}
+
+	return os.MkdirAll(p, 0755)
+}
+
+func (c *Converter) write(m map[string]string) error {
+	for k, v := range m {
+		p := filepath.Join(c.outputDir, k)
+		err := ioutil.WriteFile(p, []byte(v), 0644)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}