Handle non-tty mode

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)

libcontainer/nsinit/exec.go

@@ -16,10 +16,21 @@ import (
 	"syscall"
 )
 
-func execCommand(container *libcontainer.Container, args []string) (int, error) {
-	master, console, err := createMasterAndConsole()
-	if err != nil {
-		return -1, err
+func execCommand(container *libcontainer.Container, tty bool, args []string) (int, error) {
+	var (
+		master  *os.File
+		console string
+		err     error
+
+		inPipe           io.WriteCloser
+		outPipe, errPipe io.ReadCloser
+	)
+
+	if tty {
+		master, console, err = createMasterAndConsole()
+		if err != nil {
+			return -1, err
+		}
 	}
 
 	// create a pipe so that we can syncronize with the namespaced process and
@@ -32,6 +43,21 @@ func execCommand(container *libcontainer.Container, args []string) (int, error)
 
 	command := createCommand(container, console, r.Fd(), args)
 
+	if !tty {
+		inPipe, err = command.StdinPipe()
+		if err != nil {
+			return -1, err
+		}
+		outPipe, err = command.StdoutPipe()
+		if err != nil {
+			return -1, err
+		}
+		errPipe, err = command.StderrPipe()
+		if err != nil {
+			return -1, err
+		}
+	}
+
 	if err := command.Start(); err != nil {
 		return -1, err
 	}
@@ -63,15 +89,20 @@ func execCommand(container *libcontainer.Container, args []string) (int, error)
 	w.Close()
 	r.Close()
 
-	go io.Copy(os.Stdout, master)
-	go io.Copy(master, os.Stdin)
-
-	state, err := setupWindow(master)
-	if err != nil {
-		command.Process.Kill()
-		return -1, err
+	if tty {
+		go io.Copy(os.Stdout, master)
+		go io.Copy(master, os.Stdin)
+		state, err := setupWindow(master)
+		if err != nil {
+			command.Process.Kill()
+			return -1, err
+		}
+		defer term.RestoreTerminal(os.Stdin.Fd(), state)
+	} else {
+		go io.Copy(inPipe, os.Stdin)
+		go io.Copy(os.Stdout, outPipe)
+		go io.Copy(os.Stderr, errPipe)
 	}
-	defer term.RestoreTerminal(os.Stdin.Fd(), state)
 
 	if err := command.Wait(); err != nil {
 		if _, ok := err.(*exec.ExitError); !ok {

libcontainer/nsinit/init.go

@@ -27,23 +27,27 @@ func initCommand(container *libcontainer.Container, console string, pipe io.Read
 		return err
 	}
 
-	// close pipes so that we can replace it with the pty
-	os.Stdin.Close()
-	os.Stdout.Close()
-	os.Stderr.Close()
+	if console != "" {
+		// close pipes so that we can replace it with the pty
+		os.Stdin.Close()
+		os.Stdout.Close()
+		os.Stderr.Close()
+		slave, err := openTerminal(console, syscall.O_RDWR)
+		if err != nil {
+			return fmt.Errorf("open terminal %s", err)
+		}
+		if err := dupSlave(slave); err != nil {
+			return fmt.Errorf("dup2 slave %s", err)
+		}
+	}
 
-	slave, err := openTerminal(console, syscall.O_RDWR)
-	if err != nil {
-		return fmt.Errorf("open terminal %s", err)
-	}
-	if err := dupSlave(slave); err != nil {
-		return fmt.Errorf("dup2 slave %s", err)
-	}
 	if _, err := system.Setsid(); err != nil {
 		return fmt.Errorf("setsid %s", err)
 	}
-	if err := system.Setctty(); err != nil {
-		return fmt.Errorf("setctty %s", err)
+	if console != "" {
+		if err := system.Setctty(); err != nil {
+			return fmt.Errorf("setctty %s", err)
+		}
 	}
 	if err := system.ParentDeathSignal(); err != nil {
 		return fmt.Errorf("parent deth signal %s", err)

libcontainer/nsinit/main.go

@@ -17,8 +17,11 @@ var (
 )
 
 func main() {
-	console := flag.String("console", "", "Console (pty slave) name")
-	pipeFd := flag.Int("pipe", 0, "sync pipe fd")
+	var (
+		console = flag.String("console", "", "Console (pty slave) name")
+		tty     = flag.Bool("tty", false, "Create a tty")
+		pipeFd  = flag.Int("pipe", 0, "sync pipe fd")
+	)
 	flag.Parse()
 
 	container, err := loadContainer()
@@ -41,7 +44,7 @@ func main() {
 		if nspid > 0 {
 			exitCode, err = execinCommand(container, nspid, flag.Args()[1:])
 		} else {
-			exitCode, err = execCommand(container, flag.Args()[1:])
+			exitCode, err = execCommand(container, *tty, flag.Args()[1:])
 		}
 		if err != nil {
 			log.Fatal(err)

libcontainer/nsinit/mount.go

@@ -40,8 +40,10 @@ func setupNewMountNamespace(rootfs, console string, readonly bool) error {
 	if err := setupDev(rootfs); err != nil {
 		return err
 	}
-	if err := setupPtmx(rootfs, console); err != nil {
-		return err
+	if console != "" {
+		if err := setupPtmx(rootfs, console); err != nil {
+			return err
+		}
 	}
 	if err := system.Chdir(rootfs); err != nil {
 		return fmt.Errorf("chdir into %s %s", rootfs, err)