Merge pull request docker-archive#407 from LK4D4/move_console_to_process

Move tty configuration to Process

Author: Mrunal Patel

configs/config.go

@@ -49,9 +49,6 @@ type Config struct {
 	// Hostname optionally sets the container's hostname if provided
 	Hostname string `json:"hostname"`
 
-	// Console is the path to the console allocated to the container.
-	Console string `json:"console"`
-
 	// Namespaces specifies the container's namespaces that it should setup when cloning the init process
 	// If a namespace is not provided that namespace is shared from the container's parent process
 	Namespaces Namespaces `json:"namespaces"`

console_linux.go

@@ -12,9 +12,9 @@ import (
 	"github.com/docker/libcontainer/label"
 )
 
-// NewConsole returns an initalized console that can be used within a container by copying bytes
+// newConsole returns an initalized console that can be used within a container by copying bytes
 // from the master side to the slave that is attached as the tty for the container's init process.
-func NewConsole(uid, gid int) (Console, error) {
+func newConsole(uid, gid int) (Console, error) {
 	master, err := os.OpenFile("/dev/ptmx", syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_CLOEXEC, 0)
 	if err != nil {
 		return nil, err

container_linux.go

@@ -181,11 +181,12 @@ func (c *linuxContainer) newSetnsProcess(p *Process, cmd *exec.Cmd, parentPipe,
 
 func (c *linuxContainer) newInitConfig(process *Process) *initConfig {
 	return &initConfig{
-		Config: c.config,
-		Args:   process.Args,
-		Env:    process.Env,
-		User:   process.User,
-		Cwd:    process.Cwd,
+		Config:  c.config,
+		Args:    process.Args,
+		Env:     process.Env,
+		User:    process.User,
+		Cwd:     process.Cwd,
+		Console: process.consolePath,
 	}
 }
 

init_linux.go

@@ -45,6 +45,7 @@ type initConfig struct {
 	Cwd      string          `json:"cwd"`
 	User     string          `json:"user"`
 	Config   *configs.Config `json:"config"`
+	Console  string          `json:"console"`
 	Networks []*network      `json:"network"`
 }
 

nsinit/exec.go

@@ -41,23 +41,11 @@ func execAction(context *cli.Context) {
 	if err != nil {
 		fatal(err)
 	}
-	rootuid, err := config.HostUID()
-	if err != nil {
-		fatal(err)
-	}
-	tty, err := newTty(context, rootuid)
-	if err != nil {
-		fatal(err)
-	}
 	created := false
 	container, err := factory.Load(context.String("id"))
 	if err != nil {
-		if tty.console != nil {
-			config.Console = tty.console.Path()
-		}
 		created = true
 		if container, err = factory.Create(context.String("id"), config); err != nil {
-			tty.Close()
 			fatal(err)
 		}
 	}
@@ -70,6 +58,14 @@ func execAction(context *cli.Context) {
 		Stdout: os.Stdout,
 		Stderr: os.Stderr,
 	}
+	rootuid, err := config.HostUID()
+	if err != nil {
+		fatal(err)
+	}
+	tty, err := newTty(context, process, rootuid)
+	if err != nil {
+		fatal(err)
+	}
 	if err := tty.attach(process); err != nil {
 		fatal(err)
 	}

nsinit/tty.go

@@ -9,9 +9,9 @@ import (
 	"github.com/docker/libcontainer"
 )
 
-func newTty(context *cli.Context, rootuid int) (*tty, error) {
+func newTty(context *cli.Context, p *libcontainer.Process, rootuid int) (*tty, error) {
 	if context.Bool("tty") {
-		console, err := libcontainer.NewConsole(rootuid, rootuid)
+		console, err := p.NewConsole(rootuid)
 		if err != nil {
 			return nil, err
 		}

process.go

@@ -36,6 +36,9 @@ type Process struct {
 	// Stderr is a pointer to a writer which receives the standard error stream.
 	Stderr io.Writer
 
+	// consolePath is the path to the console allocated to the container.
+	consolePath string
+
 	ops processOperations
 }
 
@@ -63,3 +66,13 @@ func (p Process) Signal(sig os.Signal) error {
 	}
 	return p.ops.signal(sig)
 }
+
+// NewConsole creates new console for process and returns it
+func (p *Process) NewConsole(rootuid int) (Console, error) {
+	console, err := newConsole(rootuid, rootuid)
+	if err != nil {
+		return nil, err
+	}
+	p.consolePath = console.Path()
+	return console, nil
+}

rootfs_linux.go

@@ -41,7 +41,7 @@ var baseMounts = []*configs.Mount{
 
 // setupRootfs sets up the devices, mount points, and filesystems for use inside a
 // new mount namespace.
-func setupRootfs(config *configs.Config) (err error) {
+func setupRootfs(config *configs.Config, console *linuxConsole) (err error) {
 	if err := prepareRoot(config); err != nil {
 		return newSystemError(err)
 	}
@@ -53,7 +53,7 @@ func setupRootfs(config *configs.Config) (err error) {
 	if err := createDevices(config); err != nil {
 		return newSystemError(err)
 	}
-	if err := setupPtmx(config); err != nil {
+	if err := setupPtmx(config, console); err != nil {
 		return newSystemError(err)
 	}
 	// stdin, stdout and stderr could be pointing to /dev/null from parent namespace.
@@ -255,16 +255,15 @@ func setReadonly() error {
 	return syscall.Mount("/", "/", "bind", syscall.MS_BIND|syscall.MS_REMOUNT|syscall.MS_RDONLY|syscall.MS_REC, "")
 }
 
-func setupPtmx(config *configs.Config) error {
+func setupPtmx(config *configs.Config, console *linuxConsole) error {
 	ptmx := filepath.Join(config.Rootfs, "dev/ptmx")
 	if err := os.Remove(ptmx); err != nil && !os.IsNotExist(err) {
 		return err
 	}
 	if err := os.Symlink("pts/ptmx", ptmx); err != nil {
 		return fmt.Errorf("symlink dev ptmx %s", err)
 	}
-	if config.Console != "" {
-		console := newConsoleFromPath(config.Console)
+	if console != nil {
 		return console.mount(config.Rootfs, config.MountLabel, 0, 0)
 	}
 	return nil

standard_init_linux.go

@@ -20,17 +20,17 @@ func (l *linuxStandardInit) Init() error {
 	if err := joinExistingNamespaces(l.config.Config.Namespaces); err != nil {
 		return err
 	}
-	consolePath := l.config.Config.Console
-	if consolePath != "" {
-		console := newConsoleFromPath(consolePath)
+	var console *linuxConsole
+	if l.config.Console != "" {
+		console = newConsoleFromPath(l.config.Console)
 		if err := console.dupStdio(); err != nil {
 			return err
 		}
 	}
 	if _, err := syscall.Setsid(); err != nil {
 		return err
 	}
-	if consolePath != "" {
+	if console != nil {
 		if err := system.Setctty(); err != nil {
 			return err
 		}
@@ -47,7 +47,7 @@ func (l *linuxStandardInit) Init() error {
 	label.Init()
 	// InitializeMountNamespace() can be executed only for a new mount namespace
 	if l.config.Config.Namespaces.Contains(configs.NEWNS) {
-		if err := setupRootfs(l.config.Config); err != nil {
+		if err := setupRootfs(l.config.Config, console); err != nil {
 			return err
 		}
 	}