runc/container_linux.go

// +build linux

package libcontainer

import (
	"encoding/json"
	"fmt"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"syscall"

	"github.com/Sirupsen/logrus"
	"github.com/docker/libcontainer/cgroups"
	"github.com/docker/libcontainer/configs"
	"github.com/docker/libcontainer/criurpc"
	"github.com/golang/protobuf/proto"
)

const stdioFdCount = 3

type linuxContainer struct {
	id            string
	root          string
	config        *configs.Config
	cgroupManager cgroups.Manager
	initPath      string
	initArgs      []string
	initProcess   parentProcess
	criuPath      string
	m             sync.Mutex
}

// ID returns the container's unique ID
func (c *linuxContainer) ID() string {
	return c.id
}

// Config returns the container's configuration
func (c *linuxContainer) Config() configs.Config {
	return *c.config
}

func (c *linuxContainer) Status() (Status, error) {
	c.m.Lock()
	defer c.m.Unlock()
	return c.currentStatus()
}

func (c *linuxContainer) State() (*State, error) {
	c.m.Lock()
	defer c.m.Unlock()
	return c.currentState()
}

func (c *linuxContainer) Processes() ([]int, error) {
	pids, err := c.cgroupManager.GetPids()
	if err != nil {
		return nil, newSystemError(err)
	}
	return pids, nil
}

func (c *linuxContainer) Stats() (*Stats, error) {
	var (
		err   error
		stats = &Stats{}
	)
	if stats.CgroupStats, err = c.cgroupManager.GetStats(); err != nil {
		return stats, newSystemError(err)
	}
	for _, iface := range c.config.Networks {
		switch iface.Type {
		case "veth":
			istats, err := getNetworkInterfaceStats(iface.HostInterfaceName)
			if err != nil {
				return stats, newSystemError(err)
			}
			stats.Interfaces = append(stats.Interfaces, istats)
		}
	}
	return stats, nil
}

func (c *linuxContainer) Set(config configs.Config) error {
	c.m.Lock()
	defer c.m.Unlock()
	c.config = &config
	return c.cgroupManager.Set(c.config)
}

func (c *linuxContainer) Start(process *Process) error {
	c.m.Lock()
	defer c.m.Unlock()
	status, err := c.currentStatus()
	if err != nil {
		return err
	}
	doInit := status == Destroyed
	parent, err := c.newParentProcess(process, doInit)
	if err != nil {
		return newSystemError(err)
	}
	if err := parent.start(); err != nil {
		// terminate the process to ensure that it properly is reaped.
		if err := parent.terminate(); err != nil {
			logrus.Warn(err)
		}
		return newSystemError(err)
	}
	process.ops = parent
	if doInit {
		c.updateState(parent)
	}
	return nil
}

func (c *linuxContainer) newParentProcess(p *Process, doInit bool) (parentProcess, error) {
	parentPipe, childPipe, err := newPipe()
	if err != nil {
		return nil, newSystemError(err)
	}
	cmd, err := c.commandTemplate(p, childPipe)
	if err != nil {
		return nil, newSystemError(err)
	}
	if !doInit {
		return c.newSetnsProcess(p, cmd, parentPipe, childPipe), nil
	}
	return c.newInitProcess(p, cmd, parentPipe, childPipe)
}

func (c *linuxContainer) commandTemplate(p *Process, childPipe *os.File) (*exec.Cmd, error) {
	cmd := &exec.Cmd{
		Path: c.initPath,
		Args: c.initArgs,
	}
	cmd.Stdin = p.Stdin
	cmd.Stdout = p.Stdout
	cmd.Stderr = p.Stderr
	cmd.Dir = c.config.Rootfs
	if cmd.SysProcAttr == nil {
		cmd.SysProcAttr = &syscall.SysProcAttr{}
	}
	cmd.ExtraFiles = append(p.ExtraFiles, childPipe)
	cmd.Env = append(cmd.Env, fmt.Sprintf("_LIBCONTAINER_INITPIPE=%d", stdioFdCount+len(cmd.ExtraFiles)-1))
	// NOTE: when running a container with no PID namespace and the parent process spawning the container is
	// PID1 the pdeathsig is being delivered to the container's init process by the kernel for some reason
	// even with the parent still running.
	if c.config.ParentDeathSignal > 0 {
		cmd.SysProcAttr.Pdeathsig = syscall.Signal(c.config.ParentDeathSignal)
	}
	return cmd, nil
}

func (c *linuxContainer) newInitProcess(p *Process, cmd *exec.Cmd, parentPipe, childPipe *os.File) (*initProcess, error) {
	t := "_LIBCONTAINER_INITTYPE=standard"
	cloneFlags := c.config.Namespaces.CloneFlags()
	if cloneFlags&syscall.CLONE_NEWUSER != 0 {
		if err := c.addUidGidMappings(cmd.SysProcAttr); err != nil {
			// user mappings are not supported
			return nil, err
		}
		// Default to root user when user namespaces are enabled.
		if cmd.SysProcAttr.Credential == nil {
			cmd.SysProcAttr.Credential = &syscall.Credential{}
		}
	}
	cmd.Env = append(cmd.Env, t)
	cmd.SysProcAttr.Cloneflags = cloneFlags
	return &initProcess{
		cmd:        cmd,
		childPipe:  childPipe,
		parentPipe: parentPipe,
		manager:    c.cgroupManager,
		config:     c.newInitConfig(p),
	}, nil
}

func (c *linuxContainer) newSetnsProcess(p *Process, cmd *exec.Cmd, parentPipe, childPipe *os.File) *setnsProcess {
	cmd.Env = append(cmd.Env,
		fmt.Sprintf("_LIBCONTAINER_INITPID=%d", c.initProcess.pid()),
		"_LIBCONTAINER_INITTYPE=setns",
	)
	if p.consolePath != "" {
		cmd.Env = append(cmd.Env, "_LIBCONTAINER_CONSOLE_PATH="+p.consolePath)
	}
	// TODO: set on container for process management
	return &setnsProcess{
		cmd:         cmd,
		cgroupPaths: c.cgroupManager.GetPaths(),
		childPipe:   childPipe,
		parentPipe:  parentPipe,
		config:      c.newInitConfig(p),
	}
}

func (c *linuxContainer) newInitConfig(process *Process) *initConfig {
	return &initConfig{
		Config:           c.config,
		Args:             process.Args,
		Env:              process.Env,
		User:             process.User,
		Cwd:              process.Cwd,
		Console:          process.consolePath,
		Capabilities:     process.Capabilities,
		PassedFilesCount: len(process.ExtraFiles),
	}
}

func newPipe() (parent *os.File, child *os.File, err error) {
	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_STREAM|syscall.SOCK_CLOEXEC, 0)
	if err != nil {
		return nil, nil, err
	}
	return os.NewFile(uintptr(fds[1]), "parent"), os.NewFile(uintptr(fds[0]), "child"), nil
}

func (c *linuxContainer) Destroy() error {
	c.m.Lock()
	defer c.m.Unlock()
	// Since the state.json and CRIU image files are in the c.root
	// directory, we should not remove it after checkpoint.  Also,
	// when     CRIU exits after restore, we should not kill the processes.
	if _, err := os.Stat(filepath.Join(c.root, "checkpoint")); err == nil {
		return nil
	}
	status, err := c.currentStatus()
	if err != nil {
		return err
	}
	if status != Destroyed {
		return newGenericError(fmt.Errorf("container is not destroyed"), ContainerNotStopped)
	}
	if !c.config.Namespaces.Contains(configs.NEWPID) {
		if err := killCgroupProcesses(c.cgroupManager); err != nil {
			logrus.Warn(err)
		}
	}
	err = c.cgroupManager.Destroy()
	if rerr := os.RemoveAll(c.root); err == nil {
		err = rerr
	}
	c.initProcess = nil
	return err
}

func (c *linuxContainer) Pause() error {
	c.m.Lock()
	defer c.m.Unlock()
	return c.cgroupManager.Freeze(configs.Frozen)
}

func (c *linuxContainer) Resume() error {
	c.m.Lock()
	defer c.m.Unlock()
	return c.cgroupManager.Freeze(configs.Thawed)
}

func (c *linuxContainer) NotifyOOM() (<-chan struct{}, error) {
	return notifyOnOOM(c.cgroupManager.GetPaths())
}

// XXX debug support, remove when debugging done.
func addArgsFromEnv(evar string, args *[]string) {
	if e := os.Getenv(evar); e != "" {
		for _, f := range strings.Fields(e) {
			*args = append(*args, f)
		}
	}
	fmt.Printf(">>> criu %v\n", *args)
}

func (c *linuxContainer) checkCriuVersion() error {
	var x, y, z int

	out, err := exec.Command(c.criuPath, "-V").Output()
	if err != nil {
		return err
	}

	n, err := fmt.Sscanf(string(out), "Version: %d.%d.%d", &x, &y, &z)
	if n < 2 || err != nil {
		return fmt.Errorf("Unable to parse the CRIU version: %s", out)
	}

	if x*10000+y*100+z < 10501 {
		return fmt.Errorf("CRIU version must be 1.5.1 or higher")
	}

	return nil
}

func (c *linuxContainer) Checkpoint() error {
	c.m.Lock()
	defer c.m.Unlock()

	if err := c.checkCriuVersion(); err != nil {
		return err
	}

	imagePath := filepath.Join(c.root, "checkpoint")
	// Since a container can be C/R'ed multiple times,
	// the checkpoint directory may already exist.
	if err := os.Mkdir(imagePath, 0655); err != nil && !os.IsExist(err) {
		return err
	}
	workPath := filepath.Join(c.root, "criu.work")
	if err := os.Mkdir(workPath, 0655); err != nil && !os.IsExist(err) {
		return err
	}
	args := []string{
		"dump", "-v4",
		"--images-dir", imagePath,
		"--work-dir", workPath,
		"-o", "dump.log",
		"--root", c.config.Rootfs,
		"--manage-cgroups", "--evasive-devices",
		"-t", strconv.Itoa(c.initProcess.pid()),
	}
	for _, m := range c.config.Mounts {
		if m.Device == "bind" {
			args = append(args,
				"--ext-mount-map", fmt.Sprintf("%s:%s", m.Destination, m.Destination))
		}
	}
	addArgsFromEnv("CRIU_C", &args) // XXX debug
	if err := exec.Command(c.criuPath, args...).Run(); err != nil {
		return err
	}
	log.Info("Checkpointed")
	return nil
}

func (c *linuxContainer) Restore(process *Process) error {
	c.m.Lock()
	defer c.m.Unlock()

	if err := c.checkCriuVersion(); err != nil {
		return err
	}

	pidfile := filepath.Join(c.root, "restoredpid")
	// Make sure pidfile doesn't already exist from a
	// previous restore.  Otherwise, CRIU will fail.
	if err := os.Remove(pidfile); err != nil && !os.IsNotExist(err) {
		return err
	}

	fds, err := syscall.Socketpair(syscall.AF_LOCAL, syscall.SOCK_SEQPACKET|syscall.SOCK_CLOEXEC, 0)
	if err != nil {
		return err
	}

	criuClient := os.NewFile(uintptr(fds[0]), "criu-transport-client")
	criuServer := os.NewFile(uintptr(fds[1]), "criu-transport-server")
	defer criuClient.Close()
	defer criuServer.Close()

	workPath := filepath.Join(c.root, "criu.work")
	// Since a container can be C/R'ed multiple times,
	// the work directory may already exist.
	if err := os.Mkdir(workPath, 0655); err != nil && !os.IsExist(err) {
		return err
	}
	workDir, err := os.Open(workPath)
	if err != nil {
		return err
	}
	defer workDir.Close()

	imagePath := filepath.Join(c.root, "checkpoint")
	imageDir, err := os.Open(imagePath)
	if err != nil {
		return err
	}
	defer imageDir.Close()
	t := criurpc.CriuReqType_RESTORE
	req := criurpc.CriuReq{
		Type: &t,
		Opts: &criurpc.CriuOpts{
			ImagesDirFd:    proto.Int32(int32(imageDir.Fd())),
			WorkDirFd:      proto.Int32(int32(workDir.Fd())),
			EvasiveDevices: proto.Bool(true),
			LogLevel:       proto.Int32(4),
			LogFile:        proto.String("restore.log"),
			RstSibling:     proto.Bool(true),
			Root:           proto.String(c.config.Rootfs),
			ManageCgroups:  proto.Bool(true),
			NotifyScripts:  proto.Bool(true),
		},
	}
	for _, m := range c.config.Mounts {
		if m.Device == "bind" {
			extMnt := new(criurpc.ExtMountMap)
			extMnt.Key = proto.String(m.Destination)
			extMnt.Val = proto.String(m.Source)
			req.Opts.ExtMnt = append(req.Opts.ExtMnt, extMnt)
		}
	}
	// Pipes that were previously set up for std{in,out,err}
	// were removed after checkpoint.  Use the new ones.
	var i int32
	for i = 0; i < 3; i++ {
		if s := c.config.StdFds[i]; strings.Contains(s, "pipe:") {
			inheritFd := new(criurpc.InheritFd)
			inheritFd.Key = proto.String(s)
			inheritFd.Fd = proto.Int32(i)
			req.Opts.InheritFd = append(req.Opts.InheritFd, inheritFd)
		}
	}

	// XXX This doesn't really belong here as our caller should have
	//     already set up root (including devices) and mounted it.
	/*
		// remount root for restore
		if err := syscall.Mount(c.config.Rootfs, c.config.Rootfs, "bind", syscall.MS_BIND|syscall.MS_REC, ""); err != nil {
			return err
		}

		defer syscall.Unmount(c.config.Rootfs, syscall.MNT_DETACH)
	*/
	args := []string{"swrk", "3"}
	cmd := exec.Command(c.criuPath, args...)
	cmd.Stdin = process.Stdin
	cmd.Stdout = process.Stdout
	cmd.Stderr = process.Stderr
	cmd.ExtraFiles = append(cmd.ExtraFiles, criuServer)

	if err := cmd.Start(); err != nil {
		return err
	}
	criuServer.Close()

	defer func() {
		if err != nil {
			log.Errorf(filepath.Join(imagePath, "restore.log"))
		}
		criuClient.Close()
		st, err := cmd.Process.Wait()
		if err != nil {
			return
		}
		log.Warn(st.String())
	}()

	err = saveStdPipes(cmd.Process.Pid, c.config)
	if err != nil {
		return err
	}

	data, err := proto.Marshal(&req)
	if err != nil {
		return err
	}
	_, err = criuClient.Write(data)
	if err != nil {
		return err
	}

	var pid int32 = math.MinInt32

	buf := make([]byte, 10*4096)
	for true {
		n, err := criuClient.Read(buf)
		if err != nil {
			return err
		}
		if n == 0 {
			return fmt.Errorf("unexpected EOF")
		}
		if n == len(buf) {
			return fmt.Errorf("buffer is too small")
		}

		resp := new(criurpc.CriuResp)
		err = proto.Unmarshal(buf[:n], resp)
		if err != nil {
			return err
		}

		log.Debug(resp.String())
		if !resp.GetSuccess() {
			return fmt.Errorf("criu failed: type %d errno %d", t, resp.GetCrErrno())
		}

		t = resp.GetType()
		switch {
		case t == criurpc.CriuReqType_NOTIFY:
			notify := resp.GetNotify()
			if notify == nil {
				return fmt.Errorf("invalid response: %s", resp.String())
			}

			if notify.GetScript() == "setup-namespaces" {
				pid = notify.GetPid()
			}

			if notify.GetScript() == "post-restore" {
				// In many case, restore from the images can be done only once.
				// If we want to create snapshots, we need to snapshot the file system.
				os.RemoveAll(imagePath)

				r, err := newRestoredProcess(int(pid))
				if err != nil {
					return err
				}

				// TODO: crosbymichael restore previous process information by saving the init process information in
				// the container's state file or separate process state files.
				if err := c.updateState(r); err != nil {
					return err
				}
				process.ops = r
			}

			t = criurpc.CriuReqType_NOTIFY
			req = criurpc.CriuReq{
				Type:          &t,
				NotifySuccess: proto.Bool(true),
			}
			data, err = proto.Marshal(&req)
			if err != nil {
				return err
			}
			n, err = criuClient.Write(data)
			if err != nil {
				return err
			}
			continue
		case t == criurpc.CriuReqType_RESTORE:
			restore := resp.GetRestore()
			if restore != nil {
				pid = restore.GetPid()
				break
			}
		default:
			return fmt.Errorf("unable to parse the response %s", resp.String())
		}

		break
	}

	// cmd.Wait() waits cmd.goroutines which are used for proxying file descriptors.
	// Here we want to wait only the CRIU process.
	st, err := cmd.Process.Wait()
	if err != nil {
		return err
	}
	if !st.Success() {
		return fmt.Errorf("criu failed: %s", st.String())
	}
	log.Info("Restored")
	return nil
}

func (c *linuxContainer) updateState(process parentProcess) error {
	c.initProcess = process
	state, err := c.currentState()
	if err != nil {
		return err
	}
	f, err := os.Create(filepath.Join(c.root, stateFilename))
	if err != nil {
		return err
	}
	defer f.Close()
	return json.NewEncoder(f).Encode(state)
}

func (c *linuxContainer) currentStatus() (Status, error) {
	if c.initProcess == nil {
		return Destroyed, nil
	}
	// return Running if the init process is alive
	if err := syscall.Kill(c.initProcess.pid(), 0); err != nil {
		if err == syscall.ESRCH {
			return Destroyed, nil
		}
		return 0, newSystemError(err)
	}
	if c.config.Cgroups != nil && c.config.Cgroups.Freezer == configs.Frozen {
		return Paused, nil
	}
	return Running, nil
}

func (c *linuxContainer) currentState() (*State, error) {
	status, err := c.currentStatus()
	if err != nil {
		return nil, err
	}
	if status == Destroyed {
		return nil, newGenericError(fmt.Errorf("container destroyed"), ContainerNotExists)
	}
	startTime, err := c.initProcess.startTime()
	if err != nil {
		return nil, newSystemError(err)
	}
	state := &State{
		ID:                   c.ID(),
		Config:               *c.config,
		InitProcessPid:       c.initProcess.pid(),
		InitProcessStartTime: startTime,
		CgroupPaths:          c.cgroupManager.GetPaths(),
		NamespacePaths:       make(map[configs.NamespaceType]string),
	}
	for _, ns := range c.config.Namespaces {
		state.NamespacePaths[ns.Type] = ns.GetPath(c.initProcess.pid())
	}
	for _, nsType := range configs.NamespaceTypes() {
		if _, ok := state.NamespacePaths[nsType]; !ok {
			ns := configs.Namespace{Type: nsType}
			state.NamespacePaths[ns.Type] = ns.GetPath(c.initProcess.pid())
		}
	}
	return state, nil
}