Add a docker save post processor

builder/docker/driver.go

@@ -26,6 +26,9 @@ type Driver interface {
 	// Push pushes an image to a Docker index/registry.
 	Push(name string) error
 
+	// Save an image with the given ID to the given writer.
+	SaveImage(id string, dst io.Writer) error
+
 	// StartContainer starts a container and returns the ID for that container,
 	// along with a potential error.
 	StartContainer(*ContainerConfig) (string, error)

builder/docker/driver_docker.go

@@ -115,6 +115,26 @@ func (d *DockerDriver) Push(name string) error {
 	return runAndStream(cmd, d.Ui)
 }
 
+func (d *DockerDriver) SaveImage(id string, dst io.Writer) error {
+	var stderr bytes.Buffer
+	cmd := exec.Command("docker", "save", id)
+	cmd.Stdout = dst
+	cmd.Stderr = &stderr
+
+	log.Printf("Exporting image: %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) StartContainer(config *ContainerConfig) (string, error) {
 	// Build up the template data
 	var tplData startContainerTemplate

builder/docker/driver_mock.go

@@ -25,6 +25,11 @@ type MockDriver struct {
 	PushName   string
 	PushErr    error
 
+	SaveImageCalled bool
+	SaveImageId     string
+	SaveImageReader io.Reader
+	SaveImageError  error
+
 	TagImageCalled  bool
 	TagImageImageId string
 	TagImageRepo    string
@@ -94,6 +99,20 @@ func (d *MockDriver) Push(name string) error {
 	return d.PushErr
 }
 
+func (d *MockDriver) SaveImage(id string, dst io.Writer) error {
+	d.SaveImageCalled = true
+	d.SaveImageId = id
+
+	if d.SaveImageReader != nil {
+		_, err := io.Copy(dst, d.SaveImageReader)
+		if err != nil {
+			return err
+		}
+	}
+
+	return d.SaveImageError
+}
+
 func (d *MockDriver) StartContainer(config *ContainerConfig) (string, error) {
 	d.StartCalled = true
 	d.StartConfig = config

config.go

@@ -48,6 +48,7 @@ const defaultConfig = `
 		"vsphere": "packer-post-processor-vsphere",
 		"docker-push": "packer-post-processor-docker-push",
 		"docker-import": "packer-post-processor-docker-import",
+		"docker-save": "packer-post-processor-docker-save",
 		"docker-tag": "packer-post-processor-docker-tag",
 		"vagrant-cloud": "packer-post-processor-vagrant-cloud"
 	},

plugin/post-processor-docker-save/main.go

+package main
+
+import (
+	"github.com/mitchellh/packer/packer/plugin"
+	"github.com/mitchellh/packer/post-processor/docker-save"
+)
+
+func main() {
+	server, err := plugin.Server()
+	if err != nil {
+		panic(err)
+	}
+	server.RegisterPostProcessor(new(dockersave.PostProcessor))
+	server.Serve()
+}

plugin/post-processor-docker-save/main_test.go

+package main

post-processor/docker-save/post-processor.go

+package dockersave
+
+import (
+	"fmt"
+	"github.com/mitchellh/packer/builder/docker"
+	"github.com/mitchellh/packer/common"
+	"github.com/mitchellh/packer/packer"
+	"github.com/mitchellh/packer/post-processor/docker-import"
+	"os"
+)
+
+const BuilderId = "packer.post-processor.docker-save"
+
+type Config struct {
+	common.PackerConfig `mapstructure:",squash"`
+
+	Path string `mapstructure:"path"`
+
+	tpl *packer.ConfigTemplate
+}
+
+type PostProcessor struct {
+	Driver docker.Driver
+
+	config Config
+}
+
+func (p *PostProcessor) Configure(raws ...interface{}) error {
+	_, err := common.DecodeConfig(&p.config, raws...)
+	if err != nil {
+		return err
+	}
+
+	p.config.tpl, err = packer.NewConfigTemplate()
+	if err != nil {
+		return err
+	}
+	p.config.tpl.UserVars = p.config.PackerUserVars
+
+	// Accumulate any errors
+	errs := new(packer.MultiError)
+
+	templates := map[string]*string{
+		"path": &p.config.Path,
+	}
+
+	for key, ptr := range templates {
+		if *ptr == "" {
+			errs = packer.MultiErrorAppend(
+				errs, fmt.Errorf("%s must be set", key))
+		}
+
+		*ptr, err = p.config.tpl.Process(*ptr, nil)
+		if err != nil {
+			errs = packer.MultiErrorAppend(
+				errs, fmt.Errorf("Error processing %s: %s", key, err))
+		}
+	}
+
+	if len(errs.Errors) > 0 {
+		return errs
+	}
+
+	return nil
+
+}
+
+func (p *PostProcessor) PostProcess(ui packer.Ui, artifact packer.Artifact) (packer.Artifact, bool, error) {
+	if artifact.BuilderId() != dockerimport.BuilderId {
+		err := fmt.Errorf(
+			"Unknown artifact type: %s\nCan only save Docker builder artifacts.",
+			artifact.BuilderId())
+		return nil, false, err
+	}
+
+	path := p.config.Path
+
+	// Open the file that we're going to write to
+	f, err := os.Create(path)
+	if err != nil {
+		err := fmt.Errorf("Error creating output file: %s", err)
+		return nil, false, err
+	}
+
+	driver := p.Driver
+	if driver == nil {
+		// If no driver is set, then we use the real driver
+		driver = &docker.DockerDriver{Tpl: p.config.tpl, Ui: ui}
+	}
+
+	ui.Message("Saving image: " + artifact.Id())
+
+	if err := driver.SaveImage(artifact.Id(), f); err != nil {
+		f.Close()
+		os.Remove(f.Name())
+
+		return nil, false, err
+	}
+
+	f.Close()
+	ui.Message("Saved to: " + path)
+
+	return artifact, true, nil
+}

post-processor/docker-save/post-processor_test.go

+package dockersave
+
+import (
+	"bytes"
+	"github.com/mitchellh/packer/packer"
+	"testing"
+)
+
+func testConfig() map[string]interface{} {
+	return map[string]interface{}{}
+}
+
+func testPP(t *testing.T) *PostProcessor {
+	var p PostProcessor
+	if err := p.Configure(testConfig()); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	return &p
+}
+
+func testUi() *packer.BasicUi {
+	return &packer.BasicUi{
+		Reader: new(bytes.Buffer),
+		Writer: new(bytes.Buffer),
+	}
+}
+
+func TestPostProcessor_ImplementsPostProcessor(t *testing.T) {
+	var _ packer.PostProcessor = new(PostProcessor)
+}