runtime/builder with golang implementation (#2003)

runtime/builder/golang/golang.go

@@ -0,0 +1,189 @@
+package golang
+
+import (
+	"archive/tar"
+	"archive/zip"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/micro/go-micro/v3/runtime/builder"
+	"github.com/micro/go-micro/v3/runtime/local"
+)
+
+// NewBuilder returns a golang builder which can build a go binary given some source
+func NewBuilder() (builder.Builder, error) {
+	path, err := locateGo()
+	if err != nil {
+		return nil, fmt.Errorf("Error locating go binary: %v", err)
+	}
+
+	return &golang{
+		cmdPath: path,
+		tmpDir:  os.TempDir(),
+	}, nil
+}
+
+type golang struct {
+	cmdPath string
+	tmpDir  string
+}
+
+// Build a binary using source. If an archive was used, e.g. tar, this should be specified in the
+// options. If no archive option is passed, the builder will treat the source as a single file.
+func (g *golang) Build(src io.Reader, opts ...builder.Option) (io.Reader, error) {
+	// parse the options
+	var options builder.Options
+	for _, o := range opts {
+		o(&options)
+	}
+
+	// create a tmp dir to contain the source
+	dir, err := ioutil.TempDir(g.tmpDir, "src")
+	if err != nil {
+		return nil, err
+	}
+	defer os.RemoveAll(dir)
+
+	// decode the source and write to the tmp directory
+	switch options.Archive {
+	case "":
+		err = writeFile(src, dir)
+	case "tar":
+		err = unarchiveTar(src, dir)
+	case "zip":
+		err = unarchiveZip(src, dir)
+	default:
+		return nil, errors.New("Invalid Archive")
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	// determine the entrypoint if one wasn't provided
+	if len(options.Entrypoint) == 0 {
+		ep, err := local.Entrypoint(dir)
+		if err != nil {
+			return nil, err
+		}
+		options.Entrypoint = ep
+	}
+
+	// build the binary
+	cmd := exec.Command(g.cmdPath, "build", "-o", "micro_build", filepath.Dir(options.Entrypoint))
+	cmd.Env = append(os.Environ(), "GO111MODULE=auto")
+	cmd.Dir = dir
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+
+	// read the bytes from the file
+	dst, err := ioutil.ReadFile(filepath.Join(dir, "micro_build"))
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes.NewBuffer(dst), nil
+}
+
+// writeFile takes a single file to a directory
+func writeFile(src io.Reader, dir string) error {
+	// copy the source to the temp file
+	bytes, err := ioutil.ReadAll(src)
+	if err != nil {
+		return err
+	}
+
+	// write the file, note: in order for the golang builder to access the file, it cannot be
+	// os.ModeTemp. This is okay because we delete all the files in the tmp dir at the end of this
+	// function.
+	return ioutil.WriteFile(filepath.Join(dir, "main.go"), bytes, os.ModePerm)
+}
+
+// unarchiveTar decodes the source in a tar and writes it to a directory
+func unarchiveTar(src io.Reader, dir string) error {
+	tr := tar.NewReader(src)
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return err
+		}
+
+		path := filepath.Join(dir, hdr.Name)
+		bytes, err := ioutil.ReadAll(tr)
+		if err != nil {
+			return err
+		}
+
+		if err := ioutil.WriteFile(path, bytes, os.ModePerm); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// unarchiveZip decodes the source in a zip and writes it to a directory
+func unarchiveZip(src io.Reader, dir string) error {
+	// create a new buffer with the source, this is required because zip.NewReader takes a io.ReaderAt
+	// and not an io.Reader
+	buff := bytes.NewBuffer([]byte{})
+	size, err := io.Copy(buff, src)
+	if err != nil {
+		return err
+	}
+
+	// create the zip
+	reader := bytes.NewReader(buff.Bytes())
+	zip, err := zip.NewReader(reader, size)
+	if err != nil {
+		return err
+	}
+
+	// write the files in the zip to our tmp dir
+	for _, f := range zip.File {
+		rc, err := f.Open()
+		if err != nil {
+			return err
+		}
+
+		bytes, err := ioutil.ReadAll(rc)
+		if err != nil {
+			return err
+		}
+
+		path := filepath.Join(dir, f.Name)
+		if err := ioutil.WriteFile(path, bytes, os.ModePerm); err != nil {
+			return err
+		}
+
+		if err := rc.Close(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// locateGo locates the go command
+func locateGo() (string, error) {
+	if gr := os.Getenv("GOROOT"); len(gr) > 0 {
+		return filepath.Join(gr, "bin", "go"), nil
+	}
+
+	// check path
+	for _, p := range filepath.SplitList(os.Getenv("PATH")) {
+		bin := filepath.Join(p, "go")
+		if _, err := os.Stat(bin); err == nil {
+			return bin, nil
+		}
+	}
+
+	return exec.LookPath("go")
+}