@@ -39,6 +39,7 @@ func (srv *Server) Help() string {

 		{"commit", "Save the state of a container"},

 		{"attach", "Attach to the standard inputs and outputs of a running container"},

 		{"info", "Display system-wide information"},

+		{"tar", "Stream the contents of a container as a tar archive"},

 		{"web", "Generate a web UI"},

 	} {

 		help += fmt.Sprintf("    %-10.10s%s\n", cmd...)

@@ -233,9 +234,16 @@ func (srv *Server) CmdTar(stdin io.ReadCloser, stdout io.Writer, args ...string)

 		return nil

 	}

 	name := flags.Arg(0)

-	if _, exists := srv.findContainer(name); exists {

+	if container, exists := srv.findContainer(name); exists {

+		data, err := container.Filesystem.Tar()

+		if err != nil {

+			return err

+		}

 		// Stream the entire contents of the container (basically a volatile snapshot)

-		return fake.WriteFakeTar(stdout)

+		if _, err := io.Copy(stdout, data); err != nil {

+			return err

+		}

+		return nil

 	}

 	return errors.New("No such container: " + name)

 }

@@ -67,6 +67,24 @@ func (fs *Filesystem) IsMounted() bool {

 	return false

 }

+// Tar returns the contents of the filesystem as an uncompressed tar stream

+func (fs *Filesystem) Tar() (io.Reader, error) {

+	if err := fs.EnsureMounted(); err != nil {

+		return nil, err

+	}

+	return Tar(fs.RootFS)

+}

+

+

+func (fs *Filesystem) EnsureMounted() error {

+	if !fs.IsMounted() {

+		if err := fs.Mount(); err != nil {

+			return err

+		}

+	}

+	return nil

+}

+

 type ChangeType int

 const (

@@ -5,8 +5,28 @@ import (

 	"container/list"

 	"io"

 	"sync"

+	"os/exec"

 )

+// Tar generates a tar archive from a filesystem path, and returns it as a stream.

+// Path must point to a directory.

+

+func Tar(path string) (io.Reader, error) {

+	cmd := exec.Command("tar", "-C", path, "-c", ".")

+	output, err := cmd.StdoutPipe()

+	if err != nil {

+		return nil, err

+	}

+	if err := cmd.Start(); err != nil {

+		return nil, err

+	}

+	// FIXME: errors will not be passed because we don't wait for the command.

+	// Instead, consumers will hit EOF right away.

+	// This can be fixed by waiting for the process to exit, or for the first write

+	// on stdout, whichever comes first.

+	return output, nil

+}

+

 type nopWriteCloser struct {

 	io.Writer

 }