Merge branch 'f-docker-builder': Docker builder

This introduces a Docker builder. The docker builder is able to create
containers by starting an existing Docker image, provisioning it using
standard practices, and then exporting it using `docker export`.

builder/docker/artifact_export.go

@@ -0,0 +1,32 @@
+package docker
+
+import (
+	"fmt"
+	"os"
+)
+
+// ExportArtifact is an Artifact implementation for when a container is
+// exported from docker into a single flat file.
+type ExportArtifact struct {
+	path string
+}
+
+func (*ExportArtifact) BuilderId() string {
+	return BuilderId
+}
+
+func (a *ExportArtifact) Files() []string {
+	return []string{a.path}
+}
+
+func (*ExportArtifact) Id() string {
+	return "Container"
+}
+
+func (a *ExportArtifact) String() string {
+	return fmt.Sprintf("Exported Docker file: %s", a.path)
+}
+
+func (a *ExportArtifact) Destroy() error {
+	return os.Remove(a.path)
+}

builder/docker/artifact_export_test.go

@@ -0,0 +1,10 @@
+package docker
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func TestExportArtifact_impl(t *testing.T) {
+	var _ packer.Artifact = new(ExportArtifact)
+}

builder/docker/builder.go

@@ -0,0 +1,74 @@
+package docker
+
+import (
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/common"
+	"github.com/mitchellh/packer/packer"
+	"log"
+)
+
+const BuilderId = "packer.docker"
+
+type Builder struct {
+	config *Config
+	runner multistep.Runner
+}
+
+func (b *Builder) Prepare(raws ...interface{}) ([]string, error) {
+	c, warnings, errs := NewConfig(raws...)
+	if errs != nil {
+		return warnings, errs
+	}
+	b.config = c
+
+	return warnings, nil
+}
+
+func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packer.Artifact, error) {
+	steps := []multistep.Step{
+		&StepTempDir{},
+		&StepPull{},
+		&StepRun{},
+		&StepProvision{},
+		&StepExport{},
+	}
+
+	// Setup the state bag and initial state for the steps
+	state := new(multistep.BasicStateBag)
+	state.Put("config", b.config)
+	state.Put("hook", hook)
+	state.Put("ui", ui)
+
+	// Setup the driver that will talk to Docker
+	state.Put("driver", &DockerDriver{
+		Ui: ui,
+	})
+
+	// Run!
+	if b.config.PackerDebug {
+		b.runner = &multistep.DebugRunner{
+			Steps:   steps,
+			PauseFn: common.MultistepDebugFn(ui),
+		}
+	} else {
+		b.runner = &multistep.BasicRunner{Steps: steps}
+	}
+
+	b.runner.Run(state)
+
+	// If there was an error, return that
+	if rawErr, ok := state.GetOk("error"); ok {
+		return nil, rawErr.(error)
+	}
+
+	// No errors, must've worked
+	artifact := &ExportArtifact{path: b.config.ExportPath}
+	return artifact, nil
+}
+
+func (b *Builder) Cancel() {
+	if b.runner != nil {
+		log.Println("Cancelling the step runner...")
+		b.runner.Cancel()
+	}
+}

builder/docker/builder_test.go

@@ -0,0 +1,10 @@
+package docker
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func TestBuilder_implBuilder(t *testing.T) {
+	var _ packer.Builder = new(Builder)
+}

builder/docker/communicator.go

@@ -0,0 +1,290 @@
+package docker
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/ActiveState/tail"
+	"github.com/mitchellh/packer/packer"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"sync"
+	"syscall"
+	"time"
+)
+
+type Communicator struct {
+	ContainerId  string
+	HostDir      string
+	ContainerDir string
+
+	lock sync.Mutex
+}
+
+func (c *Communicator) Start(remote *packer.RemoteCmd) error {
+	// Create a temporary file to store the output. Because of a bug in
+	// Docker, sometimes all the output doesn't properly show up. This
+	// file will capture ALL of the output, and we'll read that.
+	//
+	// https://github.com/dotcloud/docker/issues/2625
+	outputFile, err := ioutil.TempFile(c.HostDir, "cmd")
+	if err != nil {
+		return err
+	}
+	outputFile.Close()
+
+	// This file will store the exit code of the command once it is complete.
+	exitCodePath := outputFile.Name() + "-exit"
+
+	cmd := exec.Command("docker", "attach", c.ContainerId)
+	stdin_w, err := cmd.StdinPipe()
+	if err != nil {
+		// We have to do some cleanup since run was never called
+		os.Remove(outputFile.Name())
+		os.Remove(exitCodePath)
+
+		return err
+	}
+
+	// Run the actual command in a goroutine so that Start doesn't block
+	go c.run(cmd, remote, stdin_w, outputFile, exitCodePath)
+
+	return nil
+}
+
+func (c *Communicator) Upload(dst string, src io.Reader) error {
+	// Create a temporary file to store the upload
+	tempfile, err := ioutil.TempFile(c.HostDir, "upload")
+	if err != nil {
+		return err
+	}
+	defer os.Remove(tempfile.Name())
+
+	// Copy the contents to the temporary file
+	_, err = io.Copy(tempfile, src)
+	tempfile.Close()
+	if err != nil {
+		return err
+	}
+
+	// Copy the file into place by copying the temporary file we put
+	// into the shared folder into the proper location in the container
+	cmd := &packer.RemoteCmd{
+		Command: fmt.Sprintf("cp %s/%s %s", c.ContainerDir,
+			filepath.Base(tempfile.Name()), dst),
+	}
+
+	if err := c.Start(cmd); err != nil {
+		return err
+	}
+
+	// Wait for the copy to complete
+	cmd.Wait()
+	if cmd.ExitStatus != 0 {
+		return fmt.Errorf("Upload failed with non-zero exit status: %d", cmd.ExitStatus)
+	}
+
+	return nil
+}
+
+func (c *Communicator) UploadDir(dst string, src string, exclude []string) error {
+	// Create the temporary directory that will store the contents of "src"
+	// for copying into the container.
+	td, err := ioutil.TempDir(c.HostDir, "dirupload")
+	if err != nil {
+		return err
+	}
+	defer os.RemoveAll(td)
+
+	walkFn := func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		relpath, err := filepath.Rel(src, path)
+		if err != nil {
+			return err
+		}
+		hostpath := filepath.Join(td, relpath)
+
+		// If it is a directory, just create it
+		if info.IsDir() {
+			return os.MkdirAll(hostpath, info.Mode())
+		}
+
+		// It is a file, copy it over, including mode.
+		src, err := os.Open(path)
+		if err != nil {
+			return err
+		}
+		defer src.Close()
+
+		dst, err := os.Create(hostpath)
+		if err != nil {
+			return err
+		}
+		defer dst.Close()
+
+		if _, err := io.Copy(dst, src); err != nil {
+			return err
+		}
+
+		si, err := src.Stat()
+		if err != nil {
+			return err
+		}
+
+		return dst.Chmod(si.Mode())
+	}
+
+	// Copy the entire directory tree to the temporary directory
+	if err := filepath.Walk(src, walkFn); err != nil {
+		return err
+	}
+
+	// Determine the destination directory
+	containerSrc := filepath.Join(c.ContainerDir, filepath.Base(td))
+	containerDst := dst
+	if src[len(src)-1] != '/' {
+		containerDst = filepath.Join(dst, filepath.Base(src))
+	}
+
+	// Make the directory, then copy into it
+	cmd := &packer.RemoteCmd{
+		Command: fmt.Sprintf("set -e; mkdir -p %s; cp -R %s/* %s",
+			containerDst, containerSrc, containerDst),
+	}
+	if err := c.Start(cmd); err != nil {
+		return err
+	}
+
+	// Wait for the copy to complete
+	cmd.Wait()
+	if cmd.ExitStatus != 0 {
+		return fmt.Errorf("Upload failed with non-zero exit status: %d", cmd.ExitStatus)
+	}
+
+	return nil
+}
+
+func (c *Communicator) Download(src string, dst io.Writer) error {
+	panic("not implemented")
+}
+
+// Runs the given command and blocks until completion
+func (c *Communicator) run(cmd *exec.Cmd, remote *packer.RemoteCmd, stdin_w io.WriteCloser, outputFile *os.File, exitCodePath string) {
+	// For Docker, remote communication must be serialized since it
+	// only supports single execution.
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	// Clean up after ourselves by removing our temporary files
+	defer os.Remove(outputFile.Name())
+	defer os.Remove(exitCodePath)
+
+	// Tail the output file and send the data to the stdout listener
+	tail, err := tail.TailFile(outputFile.Name(), tail.Config{
+		Poll:   true,
+		ReOpen: true,
+		Follow: true,
+	})
+	if err != nil {
+		log.Printf("Error tailing output file: %s", err)
+		remote.SetExited(254)
+		return
+	}
+	defer tail.Stop()
+
+	// Modify the remote command so that all the output of the commands
+	// go to a single file and so that the exit code is redirected to
+	// a single file. This lets us determine both when the command
+	// is truly complete (because the file will have data), what the
+	// exit status is (because Docker loses it because of the pty, not
+	// Docker's fault), and get the output (Docker bug).
+	remoteCmd := fmt.Sprintf("(%s) >%s 2>&1; echo $? >%s",
+		remote.Command,
+		filepath.Join(c.ContainerDir, filepath.Base(outputFile.Name())),
+		filepath.Join(c.ContainerDir, filepath.Base(exitCodePath)))
+
+	// Start the command
+	log.Printf("Executing in container %s: %#v", c.ContainerId, remoteCmd)
+	if err := cmd.Start(); err != nil {
+		log.Printf("Error executing: %s", err)
+		remote.SetExited(254)
+		return
+	}
+
+	go func() {
+		defer stdin_w.Close()
+
+		// This sleep needs to be here because of the issue linked to below.
+		// Basically, without it, Docker will hang on reading stdin forever,
+		// and won't see what we write, for some reason.
+		//
+		// https://github.com/dotcloud/docker/issues/2628
+		time.Sleep(2 * time.Second)
+
+		stdin_w.Write([]byte(remoteCmd + "\n"))
+	}()
+
+	// Start a goroutine to read all the lines out of the logs
+	go func() {
+		for line := range tail.Lines {
+			if remote.Stdout != nil {
+				remote.Stdout.Write([]byte(line.Text + "\n"))
+			} else {
+				log.Printf("Command stdout: %#v", line.Text)
+			}
+		}
+	}()
+
+	err = cmd.Wait()
+	if exitErr, ok := err.(*exec.ExitError); ok {
+		exitStatus := 1
+
+		// There is no process-independent way to get the REAL
+		// exit status so we just try to go deeper.
+		if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
+			exitStatus = status.ExitStatus()
+		}
+
+		// Say that we ended, since if Docker itself failed, then
+		// the command must've not run, or so we assume
+		remote.SetExited(exitStatus)
+		return
+	}
+
+	// Wait for the exit code to appear in our file...
+	log.Println("Waiting for exit code to appear for remote command...")
+	for {
+		fi, err := os.Stat(exitCodePath)
+		if err == nil && fi.Size() > 0 {
+			break
+		}
+
+		time.Sleep(1 * time.Second)
+	}
+
+	// Read the exit code
+	exitRaw, err := ioutil.ReadFile(exitCodePath)
+	if err != nil {
+		log.Printf("Error executing: %s", err)
+		remote.SetExited(254)
+		return
+	}
+
+	exitStatus, err := strconv.ParseInt(string(bytes.TrimSpace(exitRaw)), 10, 0)
+	if err != nil {
+		log.Printf("Error executing: %s", err)
+		remote.SetExited(254)
+		return
+	}
+	log.Printf("Executed command exit status: %d", exitStatus)
+
+	// Finally, we're done
+	remote.SetExited(int(exitStatus))
+}

builder/docker/communicator_test.go

@@ -0,0 +1,10 @@
+package docker
+
+import (
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func TestCommunicator_impl(t *testing.T) {
+	var _ packer.Communicator = new(Communicator)
+}

builder/docker/config.go

@@ -0,0 +1,75 @@
+package docker
+
+import (
+	"fmt"
+	"github.com/mitchellh/packer/common"
+	"github.com/mitchellh/packer/packer"
+)
+
+type Config struct {
+	common.PackerConfig `mapstructure:",squash"`
+
+	ExportPath string `mapstructure:"export_path"`
+	Image      string
+	Pull       bool
+
+	tpl *packer.ConfigTemplate
+}
+
+func NewConfig(raws ...interface{}) (*Config, []string, error) {
+	c := new(Config)
+	md, err := common.DecodeConfig(c, raws...)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	c.tpl, err = packer.NewConfigTemplate()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// Default Pull if it wasn't set
+	hasPull := false
+	for _, k := range md.Keys {
+		if k == "Pull" {
+			hasPull = true
+			break
+		}
+	}
+
+	if !hasPull {
+		c.Pull = true
+	}
+
+	errs := common.CheckUnusedConfig(md)
+
+	templates := map[string]*string{
+		"export_path": &c.ExportPath,
+		"image":       &c.Image,
+	}
+
+	for n, ptr := range templates {
+		var err error
+		*ptr, err = c.tpl.Process(*ptr, nil)
+		if err != nil {
+			errs = packer.MultiErrorAppend(
+				errs, fmt.Errorf("Error processing %s: %s", n, err))
+		}
+	}
+
+	if c.ExportPath == "" {
+		errs = packer.MultiErrorAppend(errs,
+			fmt.Errorf("export_path must be specified"))
+	}
+
+	if c.Image == "" {
+		errs = packer.MultiErrorAppend(errs,
+			fmt.Errorf("image must be specified"))
+	}
+
+	if errs != nil && len(errs.Errors) > 0 {
+		return nil, nil, errs
+	}
+
+	return c, nil, nil
+}

builder/docker/config_test.go

@@ -0,0 +1,90 @@
+package docker
+
+import (
+	"testing"
+)
+
+func testConfig() map[string]interface{} {
+	return map[string]interface{}{
+		"export_path": "foo",
+		"image":       "bar",
+	}
+}
+
+func testConfigStruct(t *testing.T) *Config {
+	c, warns, errs := NewConfig(testConfig())
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", len(warns))
+	}
+	if errs != nil {
+		t.Fatalf("bad: %#v", errs)
+	}
+
+	return c
+}
+
+func testConfigErr(t *testing.T, warns []string, err error) {
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", warns)
+	}
+	if err == nil {
+		t.Fatal("should error")
+	}
+}
+
+func testConfigOk(t *testing.T, warns []string, err error) {
+	if len(warns) > 0 {
+		t.Fatalf("bad: %#v", warns)
+	}
+	if err != nil {
+		t.Fatalf("bad: %s", err)
+	}
+}
+
+func TestConfigPrepare_exportPath(t *testing.T) {
+	raw := testConfig()
+
+	// No export path
+	delete(raw, "export_path")
+	_, warns, errs := NewConfig(raw)
+	testConfigErr(t, warns, errs)
+
+	// Good export path
+	raw["export_path"] = "good"
+	_, warns, errs = NewConfig(raw)
+	testConfigOk(t, warns, errs)
+}
+
+func TestConfigPrepare_image(t *testing.T) {
+	raw := testConfig()
+
+	// No image
+	delete(raw, "image")
+	_, warns, errs := NewConfig(raw)
+	testConfigErr(t, warns, errs)
+
+	// Good image
+	raw["image"] = "path"
+	_, warns, errs = NewConfig(raw)
+	testConfigOk(t, warns, errs)
+}
+
+func TestConfigPrepare_pull(t *testing.T) {
+	raw := testConfig()
+
+	// No pull set
+	delete(raw, "pull")
+	c, warns, errs := NewConfig(raw)
+	testConfigOk(t, warns, errs)
+	if !c.Pull {
+		t.Fatal("should pull by default")
+	}
+
+	// Pull set
+	raw["pull"] = false
+	c, warns, errs = NewConfig(raw)
+	testConfigOk(t, warns, errs)
+	if c.Pull {
+		t.Fatal("should not pull")
+	}
+}

builder/docker/driver.go

@@ -0,0 +1,29 @@
+package docker
+
+import (
+	"io"
+)
+
+// Driver is the interface that has to be implemented to communicate with
+// Docker. The Driver interface also allows the steps to be tested since
+// a mock driver can be shimmed in.
+type Driver interface {
+	// Export exports the container with the given ID to the given writer.
+	Export(id string, dst io.Writer) error
+
+	// Pull should pull down the given image.
+	Pull(image string) error
+
+	// StartContainer starts a container and returns the ID for that container,
+	// along with a potential error.
+	StartContainer(*ContainerConfig) (string, error)
+
+	// StopContainer forcibly stops a container.
+	StopContainer(id string) error
+}
+
+// ContainerConfig is the configuration used to start a container.
+type ContainerConfig struct {
+	Image   string
+	Volumes map[string]string
+}

builder/docker/driver_docker.go

@@ -0,0 +1,84 @@
+package docker
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/mitchellh/packer/packer"
+	"io"
+	"log"
+	"os/exec"
+	"strings"
+)
+
+type DockerDriver struct {
+	Ui packer.Ui
+}
+
+func (d *DockerDriver) Export(id string, dst io.Writer) error {
+	var stderr bytes.Buffer
+	cmd := exec.Command("docker", "export", id)
+	cmd.Stdout = dst
+	cmd.Stderr = &stderr
+
+	log.Printf("Exporting container: %s", id)
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+
+	if err := cmd.Wait(); err != nil {
+		err = fmt.Errorf("Error exporting: %s\nStderr: %s",
+			err, stderr.String())
+		return err
+	}
+
+	return nil
+}
+
+func (d *DockerDriver) Pull(image string) error {
+	cmd := exec.Command("docker", "pull", image)
+	return runAndStream(cmd, d.Ui)
+}
+
+func (d *DockerDriver) StartContainer(config *ContainerConfig) (string, error) {
+	// Args that we're going to pass to Docker
+	args := []string{"run", "-d", "-i", "-t"}
+
+	if len(config.Volumes) > 0 {
+		volumes := make([]string, 0, len(config.Volumes))
+		for host, guest := range config.Volumes {
+			volumes = append(volumes, fmt.Sprintf("%s:%s", host, guest))
+		}
+
+		args = append(args, "-v", strings.Join(volumes, ","))
+	}
+
+	args = append(args, config.Image, "/bin/bash")
+
+	// Start the container
+	var stdout, stderr bytes.Buffer
+	cmd := exec.Command("docker", args...)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	log.Printf("Starting container with args: %v", args)
+	if err := cmd.Start(); err != nil {
+		return "", err
+	}
+
+	log.Println("Waiting for container to finish starting")
+	if err := cmd.Wait(); err != nil {
+		if _, ok := err.(*exec.ExitError); ok {
+			err = fmt.Errorf("Docker exited with a non-zero exit status.\nStderr: %s",
+				stderr.String())
+		}
+
+		return "", err
+	}
+
+	// Capture the container ID, which is alone on stdout
+	return strings.TrimSpace(stdout.String()), nil
+}
+
+func (d *DockerDriver) StopContainer(id string) error {
+	return exec.Command("docker", "kill", id).Run()
+}

builder/docker/driver_mock.go

@@ -0,0 +1,56 @@
+package docker
+
+import (
+	"io"
+)
+
+// MockDriver is a driver implementation that can be used for tests.
+type MockDriver struct {
+	ExportReader io.Reader
+	ExportError  error
+	PullError    error
+	StartID      string
+	StartError   error
+	StopError    error
+
+	ExportCalled bool
+	ExportID     string
+	PullCalled   bool
+	PullImage    string
+	StartCalled  bool
+	StartConfig  *ContainerConfig
+	StopCalled   bool
+	StopID       string
+}
+
+func (d *MockDriver) Export(id string, dst io.Writer) error {
+	d.ExportCalled = true
+	d.ExportID = id
+
+	if d.ExportReader != nil {
+		_, err := io.Copy(dst, d.ExportReader)
+		if err != nil {
+			return err
+		}
+	}
+
+	return d.ExportError
+}
+
+func (d *MockDriver) Pull(image string) error {
+	d.PullCalled = true
+	d.PullImage = image
+	return d.PullError
+}
+
+func (d *MockDriver) StartContainer(config *ContainerConfig) (string, error) {
+	d.StartCalled = true
+	d.StartConfig = config
+	return d.StartID, d.StartError
+}
+
+func (d *MockDriver) StopContainer(id string) error {
+	d.StopCalled = true
+	d.StopID = id
+	return d.StopError
+}

builder/docker/driver_mock_test.go

@@ -0,0 +1,7 @@
+package docker
+
+import "testing"
+
+func TestMockDriver_impl(t *testing.T) {
+	var _ Driver = new(MockDriver)
+}

builder/docker/drover_docker_test.go

@@ -0,0 +1,7 @@
+package docker
+
+import "testing"
+
+func TestDockerDriver_impl(t *testing.T) {
+	var _ Driver = new(DockerDriver)
+}

builder/docker/exec.go

@@ -0,0 +1,102 @@
+package docker
+
+import (
+	"fmt"
+	"github.com/mitchellh/iochan"
+	"github.com/mitchellh/packer/packer"
+	"io"
+	"log"
+	"os/exec"
+	"regexp"
+	"strings"
+	"sync"
+	"syscall"
+)
+
+func runAndStream(cmd *exec.Cmd, ui packer.Ui) error {
+	stdout_r, stdout_w := io.Pipe()
+	stderr_r, stderr_w := io.Pipe()
+	defer stdout_w.Close()
+	defer stderr_w.Close()
+
+	log.Printf("Executing: %s %v", cmd.Path, cmd.Args[1:])
+	cmd.Stdout = stdout_w
+	cmd.Stderr = stderr_w
+	if err := cmd.Start(); err != nil {
+		return err
+	}
+
+	// Create the channels we'll use for data
+	exitCh := make(chan int, 1)
+	stdoutCh := iochan.DelimReader(stdout_r, '\n')
+	stderrCh := iochan.DelimReader(stderr_r, '\n')
+
+	// Start the goroutine to watch for the exit
+	go func() {
+		defer stdout_w.Close()
+		defer stderr_w.Close()
+		exitStatus := 0
+
+		err := cmd.Wait()
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			exitStatus = 1
+
+			// There is no process-independent way to get the REAL
+			// exit status so we just try to go deeper.
+			if status, ok := exitErr.Sys().(syscall.WaitStatus); ok {
+				exitStatus = status.ExitStatus()
+			}
+		}
+
+		exitCh <- exitStatus
+	}()
+
+	// This waitgroup waits for the streaming to end
+	var streamWg sync.WaitGroup
+	streamWg.Add(2)
+
+	streamFunc := func(ch <-chan string) {
+		defer streamWg.Done()
+
+		for data := range ch {
+			data = cleanOutputLine(data)
+			if data != "" {
+				ui.Message(data)
+			}
+		}
+	}
+
+	// Stream stderr/stdout
+	go streamFunc(stderrCh)
+	go streamFunc(stdoutCh)
+
+	// Wait for the process to end and then wait for the streaming to end
+	exitStatus := <-exitCh
+	streamWg.Wait()
+
+	if exitStatus != 0 {
+		return fmt.Errorf("Bad exit status: %d", exitStatus)
+	}
+
+	return nil
+}
+
+// cleanOutputLine cleans up a line so that '\r' don't muck up the
+// UI output when we're reading from a remote command.
+func cleanOutputLine(line string) string {
+	// Build a regular expression that will get rid of shell codes
+	re := regexp.MustCompile("(?i)\x1b\\[([0-9]{1,2}(;[0-9]{1,2})?)?[a|b|m|k]")
+	line = re.ReplaceAllString(line, "")
+
+	// Trim surrounding whitespace
+	line = strings.TrimSpace(line)
+
+	// Trim up to the first carriage return, since that text would be
+	// lost anyways.
+	idx := strings.LastIndex(line, "\r")
+	if idx > -1 {
+		line = line[idx+1:]
+	}
+
+	return line
+}

builder/docker/exec_test.go

@@ -0,0 +1,24 @@
+package docker
+
+import (
+	"testing"
+)
+
+func TestCleanLine(t *testing.T) {
+	cases := []struct {
+		input  string
+		output string
+	}{
+		{
+			"\x1b[0A\x1b[2K\r8dbd9e392a96: Pulling image (precise) from ubuntu\r\x1b[0B\x1b[1A\x1b[2K\r8dbd9e392a96: Pulling image (precise) from ubuntu, endpoint: https://cdn-registry-1.docker.io/v1/\r\x1b[1B",
+			"8dbd9e392a96: Pulling image (precise) from ubuntu, endpoint: https://cdn-registry-1.docker.io/v1/",
+		},
+	}
+
+	for _, tc := range cases {
+		actual := cleanOutputLine(tc.input)
+		if actual != tc.output {
+			t.Fatalf("bad: %#v %#v", tc.input, actual)
+		}
+	}
+}

builder/docker/step_export.go

@@ -0,0 +1,42 @@
+package docker
+
+import (
+	"fmt"
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+	"os"
+)
+
+// StepExport exports the container to a flat tar file.
+type StepExport struct{}
+
+func (s *StepExport) Run(state multistep.StateBag) multistep.StepAction {
+	config := state.Get("config").(*Config)
+	driver := state.Get("driver").(Driver)
+	containerId := state.Get("container_id").(string)
+	ui := state.Get("ui").(packer.Ui)
+
+	// Open the file that we're going to write to
+	f, err := os.Create(config.ExportPath)
+	if err != nil {
+		err := fmt.Errorf("Error creating output file: %s", err)
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	ui.Say("Exporting the container")
+	if err := driver.Export(containerId, f); err != nil {
+		f.Close()
+		os.Remove(f.Name())
+
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	f.Close()
+	return multistep.ActionContinue
+}
+
+func (s *StepExport) Cleanup(state multistep.StateBag) {}

builder/docker/step_export_test.go

@@ -0,0 +1,99 @@
+package docker
+
+import (
+	"bytes"
+	"errors"
+	"github.com/mitchellh/multistep"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+func testStepExportState(t *testing.T) multistep.StateBag {
+	state := testState(t)
+	state.Put("container_id", "foo")
+	return state
+}
+
+func TestStepExport_impl(t *testing.T) {
+	var _ multistep.Step = new(StepExport)
+}
+
+func TestStepExport(t *testing.T) {
+	state := testStepExportState(t)
+	step := new(StepExport)
+	defer step.Cleanup(state)
+
+	// Create a tempfile for our output path
+	tf, err := ioutil.TempFile("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	tf.Close()
+	defer os.Remove(tf.Name())
+
+	config := state.Get("config").(*Config)
+	config.ExportPath = tf.Name()
+	driver := state.Get("driver").(*MockDriver)
+	driver.ExportReader = bytes.NewReader([]byte("data!"))
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionContinue {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we did the right thing
+	if !driver.ExportCalled {
+		t.Fatal("should've exported")
+	}
+	if driver.ExportID != "foo" {
+		t.Fatalf("bad: %#v", driver.ExportID)
+	}
+
+	// verify the data exported to the file
+	contents, err := ioutil.ReadFile(tf.Name())
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if string(contents) != "data!" {
+		t.Fatalf("bad: %#v", string(contents))
+	}
+}
+
+func TestStepExport_error(t *testing.T) {
+	state := testStepExportState(t)
+	step := new(StepExport)
+	defer step.Cleanup(state)
+
+	// Create a tempfile for our output path
+	tf, err := ioutil.TempFile("", "packer")
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	tf.Close()
+
+	if err := os.Remove(tf.Name()); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	config := state.Get("config").(*Config)
+	config.ExportPath = tf.Name()
+	driver := state.Get("driver").(*MockDriver)
+	driver.ExportError = errors.New("foo")
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionHalt {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we have an error
+	if _, ok := state.GetOk("error"); !ok {
+		t.Fatal("should have error")
+	}
+
+	// verify we didn't make that file
+	if _, err := os.Stat(tf.Name()); err == nil {
+		t.Fatal("export path shouldn't exist")
+	}
+}

builder/docker/step_provision.go

@@ -0,0 +1,33 @@
+package docker
+
+import (
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+)
+
+type StepProvision struct{}
+
+func (s *StepProvision) Run(state multistep.StateBag) multistep.StepAction {
+	containerId := state.Get("container_id").(string)
+	hook := state.Get("hook").(packer.Hook)
+	tempDir := state.Get("temp_dir").(string)
+	ui := state.Get("ui").(packer.Ui)
+
+	// Create the communicator that talks to Docker via various
+	// os/exec tricks.
+	comm := &Communicator{
+		ContainerId:  containerId,
+		HostDir:      tempDir,
+		ContainerDir: "/packer-files",
+	}
+
+	// Run the provisioning hook
+	if err := hook.Run(packer.HookProvision, ui, comm, nil); err != nil {
+		state.Put("error", err)
+		return multistep.ActionHalt
+	}
+
+	return multistep.ActionContinue
+}
+
+func (s *StepProvision) Cleanup(state multistep.StateBag) {}

builder/docker/step_pull.go

@@ -0,0 +1,34 @@
+package docker
+
+import (
+	"fmt"
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+	"log"
+)
+
+type StepPull struct{}
+
+func (s *StepPull) Run(state multistep.StateBag) multistep.StepAction {
+	config := state.Get("config").(*Config)
+	driver := state.Get("driver").(Driver)
+	ui := state.Get("ui").(packer.Ui)
+
+	if !config.Pull {
+		log.Println("Pull disabled, won't docker pull")
+		return multistep.ActionContinue
+	}
+
+	ui.Say(fmt.Sprintf("Pulling Docker image: %s", config.Image))
+	if err := driver.Pull(config.Image); err != nil {
+		err := fmt.Errorf("Error pulling Docker image: %s", err)
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	return multistep.ActionContinue
+}
+
+func (s *StepPull) Cleanup(state multistep.StateBag) {
+}

builder/docker/step_pull_test.go

@@ -0,0 +1,73 @@
+package docker
+
+import (
+	"errors"
+	"github.com/mitchellh/multistep"
+	"testing"
+)
+
+func TestStepPull_impl(t *testing.T) {
+	var _ multistep.Step = new(StepPull)
+}
+
+func TestStepPull(t *testing.T) {
+	state := testState(t)
+	step := new(StepPull)
+	defer step.Cleanup(state)
+
+	config := state.Get("config").(*Config)
+	driver := state.Get("driver").(*MockDriver)
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionContinue {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we did the right thing
+	if !driver.PullCalled {
+		t.Fatal("should've pulled")
+	}
+	if driver.PullImage != config.Image {
+		t.Fatalf("bad: %#v", driver.PullImage)
+	}
+}
+
+func TestStepPull_error(t *testing.T) {
+	state := testState(t)
+	step := new(StepPull)
+	defer step.Cleanup(state)
+
+	driver := state.Get("driver").(*MockDriver)
+	driver.PullError = errors.New("foo")
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionHalt {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we have an error
+	if _, ok := state.GetOk("error"); !ok {
+		t.Fatal("should have error")
+	}
+}
+
+func TestStepPull_noPull(t *testing.T) {
+	state := testState(t)
+	step := new(StepPull)
+	defer step.Cleanup(state)
+
+	config := state.Get("config").(*Config)
+	config.Pull = false
+
+	driver := state.Get("driver").(*MockDriver)
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionContinue {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we did the right thing
+	if driver.PullCalled {
+		t.Fatal("shouldn't have pulled")
+	}
+}

builder/docker/step_run.go

@@ -0,0 +1,55 @@
+package docker
+
+import (
+	"fmt"
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+)
+
+type StepRun struct {
+	containerId string
+}
+
+func (s *StepRun) Run(state multistep.StateBag) multistep.StepAction {
+	config := state.Get("config").(*Config)
+	driver := state.Get("driver").(Driver)
+	tempDir := state.Get("temp_dir").(string)
+	ui := state.Get("ui").(packer.Ui)
+
+	runConfig := ContainerConfig{
+		Image: config.Image,
+		Volumes: map[string]string{
+			tempDir: "/packer-files",
+		},
+	}
+
+	ui.Say("Starting docker container with /bin/bash")
+	containerId, err := driver.StartContainer(&runConfig)
+	if err != nil {
+		err := fmt.Errorf("Error running container: %s", err)
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	// Save the container ID
+	s.containerId = containerId
+	state.Put("container_id", s.containerId)
+	ui.Message(fmt.Sprintf("Container ID: %s", s.containerId))
+	return multistep.ActionContinue
+}
+
+func (s *StepRun) Cleanup(state multistep.StateBag) {
+	if s.containerId == "" {
+		return
+	}
+
+	// Kill the container. We don't handle errors because errors usually
+	// just mean that the container doesn't exist anymore, which isn't a
+	// big deal.
+	driver := state.Get("driver").(Driver)
+	driver.StopContainer(s.containerId)
+
+	// Reset the container ID so that we're idempotent
+	s.containerId = ""
+}

builder/docker/step_run_test.go

@@ -0,0 +1,95 @@
+package docker
+
+import (
+	"errors"
+	"github.com/mitchellh/multistep"
+	"testing"
+)
+
+func testStepRunState(t *testing.T) multistep.StateBag {
+	state := testState(t)
+	state.Put("temp_dir", "/foo")
+	return state
+}
+
+func TestStepRun_impl(t *testing.T) {
+	var _ multistep.Step = new(StepRun)
+}
+
+func TestStepRun(t *testing.T) {
+	state := testStepRunState(t)
+	step := new(StepRun)
+	defer step.Cleanup(state)
+
+	config := state.Get("config").(*Config)
+	driver := state.Get("driver").(*MockDriver)
+	driver.StartID = "foo"
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionContinue {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify we did the right thing
+	if !driver.StartCalled {
+		t.Fatal("should've called")
+	}
+	if driver.StartConfig.Image != config.Image {
+		t.Fatalf("bad: %#v", driver.StartConfig.Image)
+	}
+
+	// verify the ID is saved
+	idRaw, ok := state.GetOk("container_id")
+	if !ok {
+		t.Fatal("should've saved ID")
+	}
+
+	id := idRaw.(string)
+	if id != "foo" {
+		t.Fatalf("bad: %#v", id)
+	}
+
+	// Verify we haven't called stop yet
+	if driver.StopCalled {
+		t.Fatal("should not have stopped")
+	}
+
+	// Cleanup
+	step.Cleanup(state)
+	if !driver.StopCalled {
+		t.Fatal("should've stopped")
+	}
+	if driver.StopID != id {
+		t.Fatalf("bad: %#v", driver.StopID)
+	}
+}
+
+func TestStepRun_error(t *testing.T) {
+	state := testStepRunState(t)
+	step := new(StepRun)
+	defer step.Cleanup(state)
+
+	driver := state.Get("driver").(*MockDriver)
+	driver.StartError = errors.New("foo")
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionHalt {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// verify the ID is not saved
+	if _, ok := state.GetOk("container_id"); ok {
+		t.Fatal("shouldn't save container ID")
+	}
+
+	// Verify we haven't called stop yet
+	if driver.StopCalled {
+		t.Fatal("should not have stopped")
+	}
+
+	// Cleanup
+	step.Cleanup(state)
+	if driver.StopCalled {
+		t.Fatal("should not have stopped")
+	}
+}

builder/docker/step_temp_dir.go

@@ -0,0 +1,38 @@
+package docker
+
+import (
+	"fmt"
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+	"io/ioutil"
+	"os"
+)
+
+// StepTempDir creates a temporary directory that we use in order to
+// share data with the docker container over the communicator.
+type StepTempDir struct {
+	tempDir string
+}
+
+func (s *StepTempDir) Run(state multistep.StateBag) multistep.StepAction {
+	ui := state.Get("ui").(packer.Ui)
+
+	ui.Say("Creating a temporary directory for sharing data...")
+	td, err := ioutil.TempDir("", "packer-docker")
+	if err != nil {
+		err := fmt.Errorf("Error making temp dir: %s", err)
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	s.tempDir = td
+	state.Put("temp_dir", s.tempDir)
+	return multistep.ActionContinue
+}
+
+func (s *StepTempDir) Cleanup(state multistep.StateBag) {
+	if s.tempDir != "" {
+		os.RemoveAll(s.tempDir)
+	}
+}

builder/docker/step_temp_dir_test.go

@@ -0,0 +1,44 @@
+package docker
+
+import (
+	"github.com/mitchellh/multistep"
+	"os"
+	"testing"
+)
+
+func TestStepTempDir_impl(t *testing.T) {
+	var _ multistep.Step = new(StepTempDir)
+}
+
+func TestStepTempDir(t *testing.T) {
+	state := testState(t)
+	step := new(StepTempDir)
+	defer step.Cleanup(state)
+
+	// sanity test
+	if _, ok := state.GetOk("temp_dir"); ok {
+		t.Fatalf("temp_dir should not be in state yet")
+	}
+
+	// run the step
+	if action := step.Run(state); action != multistep.ActionContinue {
+		t.Fatalf("bad action: %#v", action)
+	}
+
+	// Verify that we got the temp dir
+	dirRaw, ok := state.GetOk("temp_dir")
+	if !ok {
+		t.Fatalf("should've made temp_dir")
+	}
+	dir := dirRaw.(string)
+
+	if _, err := os.Stat(dir); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Cleanup
+	step.Cleanup(state)
+	if _, err := os.Stat(dir); err == nil {
+		t.Fatalf("dir should be gone")
+	}
+}

builder/docker/step_test.go

@@ -0,0 +1,20 @@
+package docker
+
+import (
+	"bytes"
+	"github.com/mitchellh/multistep"
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func testState(t *testing.T) multistep.StateBag {
+	state := new(multistep.BasicStateBag)
+	state.Put("config", testConfigStruct(t))
+	state.Put("driver", &MockDriver{})
+	state.Put("hook", &packer.MockHook{})
+	state.Put("ui", &packer.BasicUi{
+		Reader: new(bytes.Buffer),
+		Writer: new(bytes.Buffer),
+	})
+	return state
+}

config.go

@@ -23,6 +23,7 @@ const defaultConfig = `
 		"amazon-chroot": "packer-builder-amazon-chroot",
 		"amazon-instance": "packer-builder-amazon-instance",
 		"digitalocean": "packer-builder-digitalocean",
+		"docker": "packer-builder-docker",
 		"openstack": "packer-builder-openstack",
 		"qemu": "packer-builder-qemu",
 		"virtualbox": "packer-builder-virtualbox",

plugin/builder-docker/main.go

@@ -0,0 +1,10 @@
+package main
+
+import (
+	"github.com/mitchellh/packer/builder/docker"
+	"github.com/mitchellh/packer/packer/plugin"
+)
+
+func main() {
+	plugin.ServeBuilder(new(docker.Builder))
+}

plugin/builder-docker/main_test.go

@@ -0,0 +1 @@
+package main

website/source/docs/builders/docker.html.markdown

@@ -0,0 +1,57 @@
+---
+layout: "docs"
+---
+
+# Docker Builder
+
+Type: `docker`
+
+The Docker builder builds [Docker](http://www.docker.io) images using
+Docker. The builder starts a Docker container, runs provisioners within
+this container, then exports the container for re-use.
+
+The Docker builder must run on a machine that supports Docker.
+
+## Basic Example
+
+Below is a fully functioning example. It doesn't do anything useful, since
+no provisioners are defined, but it will effectively repackage an image.
+
+<pre class="prettyprint">
+{
+  "type": "docker",
+  "image": "ubuntu",
+  "export_path": "image.tar"
+}
+</pre>
+
+## Configuration Reference
+
+Configuration options are organized below into two categories: required and optional. Within
+each category, the available options are alphabetized and described.
+
+Required:
+
+* `export_path` (string) - The path where the final container will be exported
+  as a tar file.
+
+* `image` (string) - The base image for the Docker container that will
+  be started. This image will be pulled from the Docker registry if it
+  doesn't already exist.
+
+Optional:
+
+* `pull` (bool) - If true, the configured image will be pulled using
+  `docker pull` prior to use. Otherwise, it is assumed the image already
+  exists and can be used. This defaults to true if not set.
+
+## Dockerfiles
+
+This builder allows you to build Docker images _without_ Dockerfiles. If
+you have a Dockerfile already made, it is simple to just run `docker build`
+manually.
+
+With this builder, you can repeatably create Docker images without the use
+a Dockerfile. You don't need to know the syntax or semantics of Dockerfiles.
+Instead, you can just provide shell scripts, Chef recipes, Puppet manifests,
+etc. to provision your Docker container just like you would a regular machine.

website/source/layouts/docs.erb

@@ -32,6 +32,7 @@
 			<li><h4>Builders</h4></li>
 			<li><a href="/docs/builders/amazon.html">Amazon EC2 (AMI)</a></li>
 			<li><a href="/docs/builders/digitalocean.html">DigitalOcean</a></li>
+			<li><a href="/docs/builders/docker.html">Docker</a></li>
 			<li><a href="/docs/builders/openstack.html">OpenStack</a></li>
 			<li><a href="/docs/builders/qemu.html">QEMU</a></li>
 			<li><a href="/docs/builders/virtualbox.html">VirtualBox</a></li>