create a tarball from a source directory including empty folders

tarball.go

// Sample script for generating a tarball from a source directory
package main

import (
	"archive/tar"
	"bytes"
	"compress/gzip"
	"io"
	"os"
	"path/filepath"
)

func main() {
	var err error
	var buf *bytes.Buffer
	var gw *gzip.Writer

	buf = new(bytes.Buffer)
	gw, err = gzip.NewWriterLevel(buf, gzip.BestCompression)
	if err != nil {
		panic(err)
	}

	err = WriteTarball(buf, os.Args[1])
	if err != nil {
		panic(err)
	}
	// gzip writer needs to close before io.Copy to a file or get an unexpected
	// EOF error on gunzip
	err = gw.Close()
	if err != nil {
		panic(err)
	}

	fo, err := os.Create(os.Args[2])
	if err != nil {
		panic(err)
	}
	defer fo.Close()
	_, err = io.Copy(fo, buf)
	if err != nil {
		panic(err)
	}
}

func WriteTarball(w io.Writer, root string) error {

	tw := tar.NewWriter(w)
	defer tw.Close()

	base := filepath.Base(root)

	return filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		hdr, err := tar.FileInfoHeader(info, info.Name())
		if err != nil {
			return err
		}
		p, err := filepath.Rel(root, path)
		if err != nil {
			return err
		}
		hdr.Name = filepath.Join(base, p)
		if err != nil {
			return err
		}

		err = tw.WriteHeader(hdr)
		if err != nil {
			return err
		}

		if info.Mode().IsDir() {
			return nil
		}
		file, err := os.Open(path)
		if err != nil {
			return err
		}
		defer file.Close()
		_, err = io.Copy(tw, file)
		return err
	})
}