Add create and start command for container lifecycle

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

Author: crosbymichael

create.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"os"
+
+	"github.com/codegangsta/cli"
+)
+
+var createCommand = cli.Command{
+	Name:  "create",
+	Usage: "create a container",
+	ArgsUsage: `<container-id>
+
+Where "<container-id>" is your name for the instance of the container that you
+are starting. The name you provide for the container instance must be unique on
+your host.`,
+	Description: `The create command creates an instance of a container for a bundle. The bundle
+is a directory with a specification file named "` + specConfig + `" and a root
+filesystem.
+
+The specification file includes an args parameter. The args parameter is used
+to specify command(s) that get run when the container is started. To change the
+command(s) that get executed on start, edit the args parameter of the spec. See
+"runc spec --help" for more explanation.`,
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "bundle, b",
+			Value: "",
+			Usage: `path to the root of the bundle directory, defaults to the current directory`,
+		},
+		cli.StringFlag{
+			Name:  "console",
+			Value: "",
+			Usage: "specify the pty slave path for use with the container",
+		},
+		cli.StringFlag{
+			Name:  "pid-file",
+			Value: "",
+			Usage: "specify the file to write the process id to",
+		},
+		cli.BoolFlag{
+			Name:  "no-pivot",
+			Usage: "do not use pivot root to jail process inside rootfs.  This should be used whenever the rootfs is on top of a ramdisk",
+		},
+	},
+	Action: func(context *cli.Context) {
+		bundle := context.String("bundle")
+		if bundle != "" {
+			if err := os.Chdir(bundle); err != nil {
+				fatal(err)
+			}
+		}
+		spec, err := loadSpec(specConfig)
+		if err != nil {
+			fatal(err)
+		}
+		notifySocket := os.Getenv("NOTIFY_SOCKET")
+		if notifySocket != "" {
+			setupSdNotify(spec, notifySocket)
+		}
+		if os.Geteuid() != 0 {
+			fatalf("runc should be run as root")
+		}
+		status, err := startContainer(context, spec, true)
+		if err != nil {
+			fatal(err)
+		}
+		// exit with the container's exit status so any external supervisor is
+		// notified of the exit with the correct exit status.
+		os.Exit(status)
+	},
+}

libcontainer/container.go

@@ -29,6 +29,13 @@ const (
 
 	// Destroyed is the status that denotes the container does not exist.
 	Destroyed
+
+	// Stopped is the status that denotes the container does not have a created or running process.
+	Stopped
+
+	// Initialized is the status where the container has all the namespaces created but the user
+	// process has not been start.
+	Initialized
 )
 
 func (s Status) String() string {
@@ -43,6 +50,10 @@ func (s Status) String() string {
 		return "paused"
 	case Destroyed:
 		return "destroyed"
+	case Stopped:
+		return "stopped"
+	case Initialized:
+		return "initialized"
 	default:
 		return "unknown"
 	}

libcontainer/container_linux.go

@@ -195,7 +195,6 @@ func (c *linuxContainer) Start(process *Process) error {
 	}
 	// generate a timestamp indicating when the container was started
 	c.created = time.Now().UTC()
-
 	c.state = &runningState{
 		c: c,
 	}
@@ -1034,31 +1033,47 @@ func (c *linuxContainer) refreshState() error {
 	if paused {
 		return c.state.transition(&pausedState{c: c})
 	}
-	running, err := c.isRunning()
+	t, err := c.runType()
 	if err != nil {
 		return err
 	}
-	if running {
+	switch t {
+	case Initialized:
+		return c.state.transition(&initializedState{c: c})
+	case Running:
 		return c.state.transition(&runningState{c: c})
 	}
 	return c.state.transition(&stoppedState{c: c})
 }
 
-func (c *linuxContainer) isRunning() (bool, error) {
+func (c *linuxContainer) runType() (Status, error) {
 	if c.initProcess == nil {
-		return false, nil
+		return Stopped, nil
 	}
+	pid := c.initProcess.pid()
 	// return Running if the init process is alive
-	if err := syscall.Kill(c.initProcess.pid(), 0); err != nil {
+	if err := syscall.Kill(pid, 0); err != nil {
 		if err == syscall.ESRCH {
 			// It means the process does not exist anymore, could happen when the
 			// process exited just when we call the function, we should not return
 			// error in this case.
-			return false, nil
+			return Stopped, nil
+		}
+		return Stopped, newSystemErrorWithCausef(err, "sending signal 0 to pid %d", pid)
+	}
+	// check if the process that is running is the init process or the user's process.
+	// this is the difference between the container Running and Created.
+	environ, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/environ", pid))
+	if err != nil {
+		return Stopped, newSystemErrorWithCausef(err, "reading /proc/%d/environ", pid)
+	}
+	check := []byte("_LIBCONTAINER")
+	for _, v := range bytes.Split(environ, []byte("\x00")) {
+		if bytes.Contains(v, check) {
+			return Initialized, nil
 		}
-		return false, newSystemErrorWithCausef(err, "sending signal 0 to pid %d", c.initProcess.pid())
 	}
-	return true, nil
+	return Running, nil
 }
 
 func (c *linuxContainer) isPaused() (bool, error) {

libcontainer/factory_linux.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
+	"os/signal"
 	"path/filepath"
 	"regexp"
 	"runtime/debug"
@@ -219,6 +220,9 @@ func (l *LinuxFactory) Type() string {
 // StartInitialization loads a container by opening the pipe fd from the parent to read the configuration and state
 // This is a low level implementation detail of the reexec and should not be consumed externally
 func (l *LinuxFactory) StartInitialization() (err error) {
+	// start the signal handler as soon as we can
+	s := make(chan os.Signal, 1024)
+	signal.Notify(s, syscall.SIGCONT)
 	fdStr := os.Getenv("_LIBCONTAINER_INITPIPE")
 	pipefd, err := strconv.Atoi(fdStr)
 	if err != nil {
@@ -260,7 +264,7 @@ func (l *LinuxFactory) StartInitialization() (err error) {
 	if err != nil {
 		return err
 	}
-	return i.Init()
+	return i.Init(s)
 }
 
 func (l *LinuxFactory) loadState(root string) (*State, error) {

libcontainer/init_linux.go

@@ -61,7 +61,7 @@ type initConfig struct {
 }
 
 type initer interface {
-	Init() error
+	Init(s chan os.Signal) error
 }
 
 func newContainerInit(t initType, pipe *os.File) (initer, error) {

libcontainer/integration/utils_test.go

@@ -127,6 +127,9 @@ func runContainer(config *configs.Config, console string, args ...string) (buffe
 	if err != nil {
 		return buffers, -1, err
 	}
+	if err := container.Signal(syscall.SIGCONT); err != nil {
+		return buffers, -1, err
+	}
 	ps, err := process.Wait()
 	if err != nil {
 		return buffers, -1, err

libcontainer/setns_init_linux.go

@@ -5,6 +5,7 @@ package libcontainer
 import (
 	"fmt"
 	"os"
+	"os/signal"
 
 	"github.com/opencontainers/runc/libcontainer/apparmor"
 	"github.com/opencontainers/runc/libcontainer/keys"
@@ -23,7 +24,7 @@ func (l *linuxSetnsInit) getSessionRingName() string {
 	return fmt.Sprintf("_ses.%s", l.config.ContainerId)
 }
 
-func (l *linuxSetnsInit) Init() error {
+func (l *linuxSetnsInit) Init(s chan os.Signal) error {
 	// do not inherit the parent's session keyring
 	if _, err := keyctl.JoinSessionKeyring(l.getSessionRingName()); err != nil {
 		return err
@@ -49,5 +50,7 @@ func (l *linuxSetnsInit) Init() error {
 			return err
 		}
 	}
+	signal.Stop(s)
+	close(s)
 	return system.Execv(l.config.Args[0], l.config.Args[0:], os.Environ())
 }

libcontainer/standard_init_linux.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"os/exec"
+	"os/signal"
 	"syscall"
 
 	"github.com/opencontainers/runc/libcontainer/apparmor"
@@ -17,7 +19,7 @@ import (
 )
 
 type linuxStandardInit struct {
-	pipe      io.ReadWriter
+	pipe      io.ReadWriteCloser
 	parentPid int
 	config    *initConfig
 }
@@ -42,7 +44,7 @@ func (l *linuxStandardInit) getSessionRingParams() (string, uint32, uint32) {
 // the kernel
 const PR_SET_NO_NEW_PRIVS = 0x26
 
-func (l *linuxStandardInit) Init() error {
+func (l *linuxStandardInit) Init(s chan os.Signal) error {
 	ringname, keepperms, newperms := l.getSessionRingParams()
 
 	// do not inherit the parent's session keyring
@@ -150,6 +152,18 @@ func (l *linuxStandardInit) Init() error {
 			return err
 		}
 	}
-
-	return system.Execv(l.config.Args[0], l.config.Args[0:], os.Environ())
+	// check for the arg before waiting to make sure it exists and it is returned
+	// as a create time error
+	name, err := exec.LookPath(l.config.Args[0])
+	if err != nil {
+		return err
+	}
+	// close the pipe to signal that we have completed our init
+	l.pipe.Close()
+	// wait for the signal to exec the users process
+	<-s
+	// clean up the signal handler
+	signal.Stop(s)
+	close(s)
+	return syscall.Exec(name, l.config.Args[0:], os.Environ())
 }

libcontainer/state_linux.go

@@ -110,11 +110,11 @@ func (r *runningState) status() Status {
 func (r *runningState) transition(s containerState) error {
 	switch s.(type) {
 	case *stoppedState:
-		running, err := r.c.isRunning()
+		t, err := r.c.runType()
 		if err != nil {
 			return err
 		}
-		if running {
+		if t == Running {
 			return newGenericError(fmt.Errorf("container still running"), ContainerNotStopped)
 		}
 		r.c.state = s
@@ -129,16 +129,38 @@ func (r *runningState) transition(s containerState) error {
 }
 
 func (r *runningState) destroy() error {
-	running, err := r.c.isRunning()
+	t, err := r.c.runType()
 	if err != nil {
 		return err
 	}
-	if running {
+	if t == Running {
 		return newGenericError(fmt.Errorf("container is not destroyed"), ContainerNotStopped)
 	}
 	return destroy(r.c)
 }
 
+type initializedState struct {
+	c *linuxContainer
+}
+
+func (i *initializedState) status() Status {
+	return Initialized
+}
+
+func (i *initializedState) transition(s containerState) error {
+	switch s.(type) {
+	case *runningState:
+		i.c.state = s
+	case *initializedState:
+		return nil
+	}
+	return newStateTransitionError(i, s)
+}
+
+func (i *initializedState) destroy() error {
+	return destroy(i.c)
+}
+
 // pausedState represents a container that is currently pause.  It cannot be destroyed in a
 // paused state and must transition back to running first.
 type pausedState struct {
@@ -161,11 +183,11 @@ func (p *pausedState) transition(s containerState) error {
 }
 
 func (p *pausedState) destroy() error {
-	isRunning, err := p.c.isRunning()
+	t, err := p.c.runType()
 	if err != nil {
 		return err
 	}
-	if !isRunning {
+	if t != Running && t != Created {
 		if err := p.c.cgroupManager.Freeze(configs.Thawed); err != nil {
 			return err
 		}

main.go

@@ -86,6 +86,7 @@ func main() {
 	}
 	app.Commands = []cli.Command{
 		checkpointCommand,
+		createCommand,
 		deleteCommand,
 		eventsCommand,
 		execCommand,
@@ -98,6 +99,7 @@ func main() {
 		resumeCommand,
 		runCommand,
 		specCommand,
+		startCommand,
 		stateCommand,
 		updateCommand,
 	}