Implement lxc driver

Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

execdriver/driver.go

@@ -1,10 +1,26 @@
 package execdriver
 
 import (
+	"errors"
 	"io"
 	"net"
+	"os/exec"
+	"sync"
+	"syscall"
+	"time"
 )
 
+var (
+	ErrCommandIsNil = errors.New("Process's cmd is nil")
+)
+
+type Driver interface {
+	Start(c *Process) error
+	Stop(c *Process) error
+	Kill(c *Process, sig int) error
+	Wait(c *Process, duration time.Duration) error
+}
+
 // Network settings of the container
 type Network struct {
 	Gateway     string
@@ -13,12 +29,44 @@ type Network struct {
 	Mtu         int
 }
 
+type State struct {
+	sync.RWMutex
+	running    bool
+	pid        int
+	exitCode   int
+	startedAt  time.Time
+	finishedAt time.Time
+}
+
+func (s *State) IsRunning() bool {
+	s.RLock()
+	defer s.RUnlock()
+	return s.running
+}
+
+func (s *State) SetRunning() error {
+	s.Lock()
+	defer s.Unlock()
+	s.running = true
+	return nil
+}
+
+func (s *State) SetStopped(exitCode int) error {
+	s.Lock()
+	defer s.Unlock()
+	s.exitCode = exitCode
+	s.running = false
+	return nil
+}
+
 // Container / Process / Whatever, we can redefine the conatiner here
 // to be what it should be and not have to carry the baggage of the
 // container type in the core with backward compat.  This is what a
 // driver needs to execute a process inside of a conatiner.  This is what
 // a container is at it's core.
-type Container struct {
+type Process struct {
+	State State
+
 	Name        string // unique name for the conatienr
 	Privileged  bool
 	User        string
@@ -28,19 +76,45 @@ type Container struct {
 	Args        []string
 	Environment map[string]string
 	WorkingDir  string
+	ConfigPath  string
 	Network     *Network // if network is nil then networking is disabled
 	Stdin       io.Reader
 	Stdout      io.Writer
 	Stderr      io.Writer
 
-	Context interface{}
+	cmd *exec.Cmd
 }
 
-// State can be handled internally in the drivers
-type Driver interface {
-	Start(c *Container) error
-	Stop(c *Container) error
-	Kill(c *Container, sig int) error
-	Running(c *Container) (bool, error)
-	Wait(c *Container, seconds int) error
+func (c *Process) SetCmd(cmd *exec.Cmd) error {
+	c.cmd = cmd
+	cmd.Stdout = c.Stdout
+	cmd.Stderr = c.Stderr
+	cmd.Stdin = c.Stdin
+	return nil
+}
+
+func (c *Process) StdinPipe() (io.WriteCloser, error) {
+	return c.cmd.StdinPipe()
+}
+
+func (c *Process) StderrPipe() (io.ReadCloser, error) {
+	return c.cmd.StderrPipe()
+}
+
+func (c *Process) StdoutPipe() (io.ReadCloser, error) {
+	return c.cmd.StdoutPipe()
+}
+
+func (c *Process) GetExitCode() int {
+	if c.cmd != nil {
+		return c.cmd.ProcessState.Sys().(syscall.WaitStatus).ExitStatus()
+	}
+	return -1
+}
+
+func (c *Process) Wait() error {
+	if c.cmd != nil {
+		return c.cmd.Wait()
+	}
+	return ErrCommandIsNil
 }

execdriver/lxc/driver.go

@@ -1,47 +1,58 @@
 package lxc
 
 import (
+	"errors"
+	"fmt"
 	"github.com/dotcloud/docker/execdriver"
 	"os/exec"
 	"strconv"
-	"sync"
+	"strings"
 	"syscall"
+	"time"
 )
 
 const (
 	startPath = "lxc-start"
 )
 
+var (
+	ErrNotRunning         = errors.New("Process could not be started")
+	ErrWaitTimeoutReached = errors.New("Wait timeout reached")
+)
+
+func init() {
+	// Register driver
+}
+
 type driver struct {
-	containerLock map[string]*sync.Mutex
+	root       string // root path for the driver to use
+	containers map[string]*execdriver.Process
 }
 
-func NewDriver() (execdriver.Driver, error) {
+func NewDriver(root string) (execdriver.Driver, error) {
 	// setup unconfined symlink
+	return &driver{
+		root:       root,
+		containers: make(map[string]*execdriver.Process),
+	}, nil
 }
 
-func (d *driver) Start(c *execdriver.Container) error {
-	l := d.getLock(c)
-	l.Lock()
-	defer l.Unlock()
-
-	running, err := d.running(c)
-	if err != nil {
-		return err
-	}
-	if running {
+func (d *driver) Start(c *execdriver.Process) error {
+	if c.State.IsRunning() {
 		return nil
 	}
 
-	configPath, err := d.generateConfig(c)
-	if err != nil {
-		return err
-	}
+	/*
+		configPath, err := d.generateConfig(c)
+		if err != nil {
+			return err
+		}
+	*/
 
 	params := []string{
 		startPath,
 		"-n", c.Name,
-		"-f", configPath,
+		"-f", c.ConfigPath,
 		"--",
 		c.InitPath,
 	}
@@ -49,8 +60,8 @@ func (d *driver) Start(c *execdriver.Container) error {
 	if c.Network != nil {
 		params = append(params,
 			"-g", c.Network.Gateway,
-			"-i", fmt.Sprintf("%s/%d", c.Network.IPAddress, c.Network, IPPrefixLen),
-			"-mtu", c.Network.Mtu,
+			"-i", fmt.Sprintf("%s/%d", c.Network.IPAddress, c.Network.IPPrefixLen),
+			"-mtu", strconv.Itoa(c.Network.Mtu),
 		)
 	}
 
@@ -72,9 +83,9 @@ func (d *driver) Start(c *execdriver.Container) error {
 	cmd := exec.Command(params[0], params[1:]...)
 	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}
 
-	cmd.Stdout = c.Stdout
-	cmd.Stderr = c.Stderr
-	cmd.Stdin = c.Stdin
+	if err := c.SetCmd(cmd); err != nil {
+		return err
+	}
 
 	if err := cmd.Start(); err != nil {
 		return err
@@ -87,58 +98,135 @@ func (d *driver) Start(c *execdriver.Container) error {
 	return nil
 }
 
-func (d *driver) Stop(c *execdriver.Container) error {
-	l := d.getLock(c)
-	l.Lock()
-	defer l.Unlock()
-
+func (d *driver) Stop(c *execdriver.Process) error {
 	if err := d.kill(c, 15); err != nil {
 		if err := d.kill(c, 9); err != nil {
 			return err
 		}
 	}
 
-	if err := d.wait(c, 10); err != nil {
-		return d.kill(c, 9)
+	if err := d.wait(c, 10*time.Second); err != nil {
+		if err := d.kill(c, 9); err != nil {
+			return err
+		}
+	}
+	exitCode := c.GetExitCode()
+	if err := c.State.SetStopped(exitCode); err != nil {
+		return err
 	}
 	return nil
 }
 
-func (d *driver) Wait(c *execdriver.Container, seconds int) error {
-	l := d.getLock(c)
-	l.Lock()
-	defer l.Unlock()
+func (d *driver) Kill(c *execdriver.Process, sig int) error {
+	c.State.Lock()
+	defer c.State.Unlock()
+	return d.kill(c, sig)
+}
 
-	return d.wait(c, seconds)
+func (d *driver) Wait(c *execdriver.Process, duration time.Duration) error {
+	return d.wait(c, duration)
 }
 
 // If seconds < 0 then wait forever
-func (d *driver) wait(c *execdriver.Container, seconds int) error {
-
+func (d *driver) wait(c *execdriver.Process, duration time.Duration) error {
+begin:
+	var (
+		killer bool
+		done   = d.waitCmd(c)
+	)
+	if duration > 0 {
+		select {
+		case err := <-done:
+			if err != nil && err == execdriver.ErrCommandIsNil {
+				done = d.waitLxc(c, &killer)
+				goto begin
+			}
+			return err
+		case <-time.After(duration):
+			killer = true
+			return ErrWaitTimeoutReached
+		}
+	} else {
+		if err := <-done; err != nil {
+			if err == execdriver.ErrCommandIsNil {
+				done = d.waitLxc(c, &killer)
+				goto begin
+			}
+			return err
+		}
+	}
+	return nil
 }
 
-func (d *driver) kill(c *execdriver.Container, sig int) error {
+func (d *driver) kill(c *execdriver.Process, sig int) error {
 	return exec.Command("lxc-kill", "-n", c.Name, strconv.Itoa(sig)).Run()
 }
 
-func (d *driver) running(c *execdriver.Container) (bool, error) {
-
-}
-
-// Generate the lxc configuration and return the path to the file
-func (d *driver) generateConfig(c *execdriver.Container) (string, error) {
-
-}
-
-func (d *driver) waitForStart(cmd *exec.Cmd, c *execdriver.Container) error {
-
-}
-
-func (d *driver) getLock(c *execdriver.Container) *sync.Mutex {
-	l, ok := d.containerLock[c.Name]
-	if !ok {
-		l = &sync.Mutex{}
-		d.containerLock[c.Name] = l
+/* Generate the lxc configuration and return the path to the file
+func (d *driver) generateConfig(c *execdriver.Process) (string, error) {
+	p := path.Join(d.root, c.Name)
+	f, err := os.Create(p)
+	if err != nil {
+		return "", nil
 	}
-	return l
+	defer f.Close()
+
+	if err := LxcTemplateCompiled.Execute(f, c.Context); err != nil {
+		return "", err
+	}
+	return p, nil
+}
+*/
+
+func (d *driver) waitForStart(cmd *exec.Cmd, c *execdriver.Process) error {
+	// We wait for the container to be fully running.
+	// Timeout after 5 seconds. In case of broken pipe, just retry.
+	// Note: The container can run and finish correctly before
+	// the end of this loop
+	for now := time.Now(); time.Since(now) < 5*time.Second; {
+		// If the container dies while waiting for it, just return
+		if !c.State.IsRunning() {
+			return nil
+		}
+		output, err := exec.Command("lxc-info", "-s", "-n", c.Name).CombinedOutput()
+		if err != nil {
+			output, err = exec.Command("lxc-info", "-s", "-n", c.Name).CombinedOutput()
+			if err != nil {
+				return err
+			}
+
+		}
+		if strings.Contains(string(output), "RUNNING") {
+			return nil
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+	return ErrNotRunning
+}
+
+func (d *driver) waitCmd(c *execdriver.Process) <-chan error {
+	done := make(chan error)
+	go func() {
+		done <- c.Wait()
+	}()
+	return done
+}
+
+func (d *driver) waitLxc(c *execdriver.Process, kill *bool) <-chan error {
+	done := make(chan error)
+	go func() {
+		for *kill {
+			output, err := exec.Command("lxc-info", "-n", c.Name).CombinedOutput()
+			if err != nil {
+				done <- err
+				return
+			}
+			if !strings.Contains(string(output), "RUNNING") {
+				done <- err
+				return
+			}
+			time.Sleep(500 * time.Millisecond)
+		}
+	}()
+	return done
 }