Merge pull request #22866 from jstarks/foreign_layers

Support layers from external URLs

distribution/pull_v2.go

@@ -133,6 +133,7 @@ type v2LayerDescriptor struct {
 	V2MetadataService *metadata.V2MetadataService
 	tmpFile           *os.File
 	verifier          digest.Verifier
+	foreignSrc        *distribution.Descriptor
 }
 
 func (ld *v2LayerDescriptor) Key() string {
@@ -180,9 +181,8 @@ func (ld *v2LayerDescriptor) Download(ctx context.Context, progressOutput progre
 	}
 
 	tmpFile := ld.tmpFile
-	blobs := ld.repo.Blobs(ctx)
 
-	layerDownload, err := blobs.Open(ctx, ld.digest)
+	layerDownload, err := ld.open(ctx)
 	if err != nil {
 		logrus.Errorf("Error initiating layer download: %v", err)
 		if err == distribution.ErrBlobUnknown {
@@ -501,6 +501,29 @@ func (p *v2Puller) pullSchema2(ctx context.Context, ref reference.Named, mfst *s
 		return imageID, manifestDigest, nil
 	}
 
+	var descriptors []xfer.DownloadDescriptor
+
+	// Note that the order of this loop is in the direction of bottom-most
+	// to top-most, so that the downloads slice gets ordered correctly.
+	for _, d := range mfst.Layers {
+		layerDescriptor := &v2LayerDescriptor{
+			digest:            d.Digest,
+			repo:              p.repo,
+			repoInfo:          p.repoInfo,
+			V2MetadataService: p.V2MetadataService,
+		}
+
+		if d.MediaType == schema2.MediaTypeForeignLayer && len(d.URLs) > 0 {
+			if !layer.ForeignSourceSupported() {
+				return "", "", errors.New("foreign layers are not supported on this OS")
+			}
+
+			layerDescriptor.foreignSrc = &d
+		}
+
+		descriptors = append(descriptors, layerDescriptor)
+	}
+
 	configChan := make(chan []byte, 1)
 	errChan := make(chan error, 1)
 	var cancel func()
@@ -517,21 +540,6 @@ func (p *v2Puller) pullSchema2(ctx context.Context, ref reference.Named, mfst *s
 		configChan <- configJSON
 	}()
 
-	var descriptors []xfer.DownloadDescriptor
-
-	// Note that the order of this loop is in the direction of bottom-most
-	// to top-most, so that the downloads slice gets ordered correctly.
-	for _, d := range mfst.References() {
-		layerDescriptor := &v2LayerDescriptor{
-			digest:            d.Digest,
-			repo:              p.repo,
-			repoInfo:          p.repoInfo,
-			V2MetadataService: p.V2MetadataService,
-		}
-
-		descriptors = append(descriptors, layerDescriptor)
-	}
-
 	var (
 		configJSON         []byte       // raw serialized image config
 		unmarshalledConfig image.Image  // deserialized image config

distribution/pull_v2_unix.go

@@ -3,6 +3,8 @@
 package distribution
 
 import (
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
 	"github.com/docker/distribution/manifest/schema1"
 	"github.com/docker/docker/image"
 )
@@ -10,3 +12,8 @@ import (
 func detectBaseLayer(is image.Store, m *schema1.Manifest, rootFS *image.RootFS) error {
 	return nil
 }
+
+func (ld *v2LayerDescriptor) open(ctx context.Context) (distribution.ReadSeekCloser, error) {
+	blobs := ld.repo.Blobs(ctx)
+	return blobs.Open(ctx, ld.digest)
+}

distribution/pull_v2_windows.go

@@ -5,9 +5,15 @@ package distribution
 import (
 	"encoding/json"
 	"fmt"
+	"net/http"
+	"os"
 
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
 	"github.com/docker/distribution/manifest/schema1"
+	"github.com/docker/distribution/registry/client/transport"
 	"github.com/docker/docker/image"
+	"github.com/docker/docker/layer"
 )
 
 func detectBaseLayer(is image.Store, m *schema1.Manifest, rootFS *image.RootFS) error {
@@ -28,3 +34,33 @@ func detectBaseLayer(is image.Store, m *schema1.Manifest, rootFS *image.RootFS)
 	}
 	return fmt.Errorf("Invalid base layer %q", v1img.Parent)
 }
+
+var _ layer.ForeignSourcer = &v2LayerDescriptor{}
+
+func (ld *v2LayerDescriptor) ForeignSource() *distribution.Descriptor {
+	return ld.foreignSrc
+}
+
+func (ld *v2LayerDescriptor) open(ctx context.Context) (distribution.ReadSeekCloser, error) {
+	if ld.foreignSrc == nil {
+		blobs := ld.repo.Blobs(ctx)
+		return blobs.Open(ctx, ld.digest)
+	}
+
+	var (
+		err error
+		rsc distribution.ReadSeekCloser
+	)
+
+	// Find the first URL that results in a 200 result code.
+	for _, url := range ld.foreignSrc.URLs {
+		rsc = transport.NewHTTPReadSeeker(http.DefaultClient, url, nil)
+		_, err = rsc.Seek(0, os.SEEK_SET)
+		if err == nil {
+			break
+		}
+		rsc.Close()
+		rsc = nil
+	}
+	return rsc, err
+}

distribution/push_v2.go

@@ -240,6 +240,13 @@ func (pd *v2PushDescriptor) DiffID() layer.DiffID {
 }
 
 func (pd *v2PushDescriptor) Upload(ctx context.Context, progressOutput progress.Output) (distribution.Descriptor, error) {
+	if fs, ok := pd.layer.(layer.ForeignSourcer); ok {
+		if d := fs.ForeignSource(); d != nil {
+			progress.Update(progressOutput, pd.ID(), "Skipped foreign layer")
+			return *d, nil
+		}
+	}
+
 	diffID := pd.DiffID()
 
 	pd.pushState.Lock()

distribution/xfer/download.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/layer"
 	"github.com/docker/docker/pkg/archive"
@@ -318,7 +319,11 @@ func (ldm *LayerDownloadManager) makeDownloadFunc(descriptor DownloadDescriptor,
 				return
 			}
 
-			d.layer, err = d.layerStore.Register(inflatedLayerData, parentLayer)
+			var src *distribution.Descriptor
+			if fs, ok := descriptor.(layer.ForeignSourcer); ok {
+				src = fs.ForeignSource()
+			}
+			d.layer, err = d.layerStore.RegisterForeign(inflatedLayerData, parentLayer, src)
 			if err != nil {
 				select {
 				case <-d.Transfer.Context().Done():
@@ -409,7 +414,11 @@ func (ldm *LayerDownloadManager) makeDownloadFuncFromDownload(descriptor Downloa
 			}
 			defer layerReader.Close()
 
-			d.layer, err = d.layerStore.Register(layerReader, parentLayer)
+			var src *distribution.Descriptor
+			if fs, ok := l.(layer.ForeignSourcer); ok {
+				src = fs.ForeignSource()
+			}
+			d.layer, err = d.layerStore.RegisterForeign(layerReader, parentLayer, src)
 			if err != nil {
 				d.err = fmt.Errorf("failed to register layer: %v", err)
 				return

distribution/xfer/download_test.go

@@ -10,6 +10,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/docker/distribution"
 	"github.com/docker/distribution/digest"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/layer"
@@ -71,6 +72,10 @@ func createChainIDFromParent(parent layer.ChainID, dgsts ...layer.DiffID) layer.
 }
 
 func (ls *mockLayerStore) Register(reader io.Reader, parentID layer.ChainID) (layer.Layer, error) {
+	return ls.RegisterForeign(reader, parentID, nil)
+}
+
+func (ls *mockLayerStore) RegisterForeign(reader io.Reader, parentID layer.ChainID, _ *distribution.Descriptor) (layer.Layer, error) {
 	var (
 		parent layer.Layer
 		err    error

hack/vendor.sh

@@ -87,7 +87,7 @@ clone git github.com/boltdb/bolt v1.2.1
 clone git github.com/miekg/dns 75e6e86cc601825c5dbcd4e0c209eab180997cd7
 
 # get graph and distribution packages
-clone git github.com/docker/distribution 9ec0d742d69f77caa4dd5f49ceb70c3067d39f30
+clone git github.com/docker/distribution 5bbf65499960b184fe8e0f045397375e1a6722b8
 clone git github.com/vbatts/tar-split v0.9.11
 
 # get go-zfs packages

image/tarexport/load.go

@@ -10,6 +10,7 @@ import (
 	"reflect"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/image/v1"
 	"github.com/docker/docker/layer"
@@ -63,6 +64,10 @@ func (l *tarexporter) Load(inTar io.ReadCloser, outStream io.Writer, quiet bool)
 	var parentLinks []parentLink
 
 	for _, m := range manifest {
+		if m.LayerSources != nil && !layer.ForeignSourceSupported() {
+			return fmt.Errorf("invalid manifest, foreign layers not supported on this operating system")
+		}
+
 		configPath, err := safePath(tmpDir, m.Config)
 		if err != nil {
 			return err
@@ -92,7 +97,7 @@ func (l *tarexporter) Load(inTar io.ReadCloser, outStream io.Writer, quiet bool)
 			r.Append(diffID)
 			newLayer, err := l.ls.Get(r.ChainID())
 			if err != nil {
-				newLayer, err = l.loadLayer(layerPath, rootFS, diffID.String(), progressOutput)
+				newLayer, err = l.loadLayer(layerPath, rootFS, diffID.String(), m.LayerSources[diffID], progressOutput)
 				if err != nil {
 					return err
 				}
@@ -151,7 +156,7 @@ func (l *tarexporter) setParentID(id, parentID image.ID) error {
 	return l.is.SetParent(id, parentID)
 }
 
-func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string, progressOutput progress.Output) (layer.Layer, error) {
+func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string, foreignSrc *distribution.Descriptor, progressOutput progress.Output) (layer.Layer, error) {
 	rawTar, err := os.Open(filename)
 	if err != nil {
 		logrus.Debugf("Error reading embedded tar: %v", err)
@@ -174,9 +179,9 @@ func (l *tarexporter) loadLayer(filename string, rootFS image.RootFS, id string,
 
 		progressReader := progress.NewProgressReader(inflatedLayerData, progressOutput, fileInfo.Size(), stringid.TruncateID(id), "Loading layer")
 
-		return l.ls.Register(progressReader, rootFS.ChainID())
+		return l.ls.RegisterForeign(progressReader, rootFS.ChainID(), foreignSrc)
 	}
-	return l.ls.Register(inflatedLayerData, rootFS.ChainID())
+	return l.ls.RegisterForeign(inflatedLayerData, rootFS.ChainID(), foreignSrc)
 }
 
 func (l *tarexporter) setLoadedTag(ref reference.NamedTagged, imgID image.ID, outStream io.Writer) error {
@@ -298,7 +303,7 @@ func (l *tarexporter) legacyLoadImage(oldID, sourceDir string, loadedMap map[str
 	if err != nil {
 		return err
 	}
-	newLayer, err := l.loadLayer(layerPath, *rootFS, oldID, progressOutput)
+	newLayer, err := l.loadLayer(layerPath, *rootFS, oldID, nil, progressOutput)
 	if err != nil {
 		return err
 	}

image/tarexport/save.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"time"
 
+	"github.com/docker/distribution"
 	"github.com/docker/distribution/digest"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/image/v1"
@@ -131,7 +132,8 @@ func (s *saveSession) save(outStream io.Writer) error {
 	var parentLinks []parentLink
 
 	for id, imageDescr := range s.images {
-		if err = s.saveImage(id); err != nil {
+		foreignSrcs, err := s.saveImage(id)
+		if err != nil {
 			return err
 		}
 
@@ -151,9 +153,10 @@ func (s *saveSession) save(outStream io.Writer) error {
 		}
 
 		manifest = append(manifest, manifestItem{
-			Config:   digest.Digest(id).Hex() + ".json",
+			Config:       digest.Digest(id).Hex() + ".json",
-			RepoTags: repoTags,
+			RepoTags:     repoTags,
-			Layers:   layers,
+			Layers:       layers,
+			LayerSources: foreignSrcs,
 		})
 
 		parentID, _ := s.is.GetParent(id)
@@ -213,18 +216,19 @@ func (s *saveSession) save(outStream io.Writer) error {
 	return nil
 }
 
-func (s *saveSession) saveImage(id image.ID) error {
+func (s *saveSession) saveImage(id image.ID) (map[layer.DiffID]*distribution.Descriptor, error) {
 	img, err := s.is.Get(id)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	if len(img.RootFS.DiffIDs) == 0 {
-		return fmt.Errorf("empty export - not implemented")
+		return nil, fmt.Errorf("empty export - not implemented")
 	}
 
 	var parent digest.Digest
 	var layers []string
+	var foreignSrcs map[layer.DiffID]*distribution.Descriptor
 	for i := range img.RootFS.DiffIDs {
 		v1Img := image.V1Image{}
 		if i == len(img.RootFS.DiffIDs)-1 {
@@ -234,7 +238,7 @@ func (s *saveSession) saveImage(id image.ID) error {
 		rootFS.DiffIDs = rootFS.DiffIDs[:i+1]
 		v1ID, err := v1.CreateID(v1Img, rootFS.ChainID(), parent)
 		if err != nil {
-			return err
+			return nil, err
 		}
 
 		v1Img.ID = v1ID.Hex()
@@ -242,79 +246,91 @@ func (s *saveSession) saveImage(id image.ID) error {
 			v1Img.Parent = parent.Hex()
 		}
 
-		if err := s.saveLayer(rootFS.ChainID(), v1Img, img.Created); err != nil {
+		src, err := s.saveLayer(rootFS.ChainID(), v1Img, img.Created)
-			return err
+		if err != nil {
+			return nil, err
 		}
 		layers = append(layers, v1Img.ID)
 		parent = v1ID
+		if src != nil {
+			if foreignSrcs == nil {
+				foreignSrcs = make(map[layer.DiffID]*distribution.Descriptor)
+			}
+			foreignSrcs[img.RootFS.DiffIDs[i]] = src
+		}
 	}
 
 	configFile := filepath.Join(s.outDir, digest.Digest(id).Hex()+".json")
 	if err := ioutil.WriteFile(configFile, img.RawJSON(), 0644); err != nil {
-		return err
+		return nil, err
 	}
 	if err := system.Chtimes(configFile, img.Created, img.Created); err != nil {
-		return err
+		return nil, err
 	}
 
 	s.images[id].layers = layers
-	return nil
+	return foreignSrcs, nil
 }
 
-func (s *saveSession) saveLayer(id layer.ChainID, legacyImg image.V1Image, createdTime time.Time) error {
+func (s *saveSession) saveLayer(id layer.ChainID, legacyImg image.V1Image, createdTime time.Time) (*distribution.Descriptor, error) {
 	if _, exists := s.savedLayers[legacyImg.ID]; exists {
-		return nil
+		return nil, nil
 	}
 
 	outDir := filepath.Join(s.outDir, legacyImg.ID)
 	if err := os.Mkdir(outDir, 0755); err != nil {
-		return err
+		return nil, err
 	}
 
 	// todo: why is this version file here?
 	if err := ioutil.WriteFile(filepath.Join(outDir, legacyVersionFileName), []byte("1.0"), 0644); err != nil {
-		return err
+		return nil, err
 	}
 
 	imageConfig, err := json.Marshal(legacyImg)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	if err := ioutil.WriteFile(filepath.Join(outDir, legacyConfigFileName), imageConfig, 0644); err != nil {
-		return err
+		return nil, err
 	}
 
 	// serialize filesystem
 	tarFile, err := os.Create(filepath.Join(outDir, legacyLayerFileName))
 	if err != nil {
-		return err
+		return nil, err
 	}
 	defer tarFile.Close()
 
 	l, err := s.ls.Get(id)
 	if err != nil {
-		return err
+		return nil, err
 	}
 	defer layer.ReleaseAndLog(s.ls, l)
 
 	arch, err := l.TarStream()
 	if err != nil {
-		return err
+		return nil, err
 	}
 	defer arch.Close()
 
 	if _, err := io.Copy(tarFile, arch); err != nil {
-		return err
+		return nil, err
 	}
 
 	for _, fname := range []string{"", legacyVersionFileName, legacyConfigFileName, legacyLayerFileName} {
 		// todo: maybe save layer created timestamp?
 		if err := system.Chtimes(filepath.Join(outDir, fname), createdTime, createdTime); err != nil {
-			return err
+			return nil, err
 		}
 	}
 
 	s.savedLayers[legacyImg.ID] = struct{}{}
-	return nil
+
+	var src *distribution.Descriptor
+	if fs, ok := l.(layer.ForeignSourcer); ok {
+		src = fs.ForeignSource()
+	}
+	return src, nil
 }

image/tarexport/tarexport.go

@@ -1,6 +1,7 @@
 package tarexport
 
 import (
+	"github.com/docker/distribution"
 	"github.com/docker/docker/image"
 	"github.com/docker/docker/layer"
 	"github.com/docker/docker/reference"
@@ -15,10 +16,11 @@ const (
 )
 
 type manifestItem struct {
-	Config   string
+	Config       string
-	RepoTags []string
+	RepoTags     []string
-	Layers   []string
+	Layers       []string
-	Parent   image.ID `json:",omitempty"`
+	Parent       image.ID                                  `json:",omitempty"`
+	LayerSources map[layer.DiffID]*distribution.Descriptor `json:",omitempty"`
 }
 
 type tarexporter struct {

layer/filestore.go

@@ -2,6 +2,7 @@ package layer
 
 import (
 	"compress/gzip"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -13,6 +14,7 @@ import (
 	"strings"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution"
 	"github.com/docker/distribution/digest"
 	"github.com/docker/docker/pkg/ioutils"
 )
@@ -24,6 +26,9 @@ var (
 		// digest.SHA384, // Currently not used
 		// digest.SHA512, // Currently not used
 	}
+
+	// ErrNoForeignSource is returned when no foreign source is set for a layer.
+	ErrNoForeignSource = errors.New("layer does not have a foreign source")
 )
 
 type fileMetadataStore struct {
@@ -98,6 +103,14 @@ func (fm *fileMetadataTransaction) SetCacheID(cacheID string) error {
 	return ioutil.WriteFile(filepath.Join(fm.root, "cache-id"), []byte(cacheID), 0644)
 }
 
+func (fm *fileMetadataTransaction) SetForeignSource(ref distribution.Descriptor) error {
+	jsonRef, err := json.Marshal(ref)
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(filepath.Join(fm.root, "descriptor.json"), jsonRef, 0644)
+}
+
 func (fm *fileMetadataTransaction) TarSplitWriter(compressInput bool) (io.WriteCloser, error) {
 	f, err := os.OpenFile(filepath.Join(fm.root, "tar-split.json.gz"), os.O_TRUNC|os.O_CREATE|os.O_WRONLY, 0644)
 	if err != nil {
@@ -191,6 +204,23 @@ func (fms *fileMetadataStore) GetCacheID(layer ChainID) (string, error) {
 	return content, nil
 }
 
+func (fms *fileMetadataStore) GetForeignSource(layer ChainID) (distribution.Descriptor, error) {
+	content, err := ioutil.ReadFile(fms.getLayerFilename(layer, "descriptor.json"))
+	if err != nil {
+		if os.IsNotExist(err) {
+			return distribution.Descriptor{}, ErrNoForeignSource
+		}
+		return distribution.Descriptor{}, err
+	}
+
+	var ref distribution.Descriptor
+	err = json.Unmarshal(content, &ref)
+	if err != nil {
+		return distribution.Descriptor{}, err
+	}
+	return ref, err
+}
+
 func (fms *fileMetadataStore) TarSplitReader(layer ChainID) (io.ReadCloser, error) {
 	fz, err := os.Open(fms.getLayerFilename(layer, "tar-split.json.gz"))
 	if err != nil {

layer/layer.go

@@ -14,6 +14,7 @@ import (
 	"io"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution"
 	"github.com/docker/distribution/digest"
 	"github.com/docker/docker/pkg/archive"
 )
@@ -107,6 +108,14 @@ type Layer interface {
 	Metadata() (map[string]string, error)
 }
 
+// ForeignSourcer is an interface used to describe the source of layers
+// and objects representing layers, when the source is a foreign URL.
+type ForeignSourcer interface {
+	// ForeignSource returns the descriptor for this layer if it is
+	// a foreign layer, or nil for ordinary layers.
+	ForeignSource() *distribution.Descriptor
+}
+
 // RWLayer represents a layer which is
 // read and writable
 type RWLayer interface {
@@ -168,6 +177,7 @@ type MountInit func(root string) error
 // read-only and read-write layers.
 type Store interface {
 	Register(io.Reader, ChainID) (Layer, error)
+	RegisterForeign(io.Reader, ChainID, *distribution.Descriptor) (Layer, error)
 	Get(ChainID) (Layer, error)
 	Release(Layer) ([]Metadata, error)
 
@@ -188,6 +198,7 @@ type MetadataTransaction interface {
 	SetParent(parent ChainID) error
 	SetDiffID(DiffID) error
 	SetCacheID(string) error
+	SetForeignSource(distribution.Descriptor) error
 	TarSplitWriter(compressInput bool) (io.WriteCloser, error)
 
 	Commit(ChainID) error
@@ -207,6 +218,7 @@ type MetadataStore interface {
 	GetParent(ChainID) (ChainID, error)
 	GetDiffID(ChainID) (DiffID, error)
 	GetCacheID(ChainID) (string, error)
+	GetForeignSource(ChainID) (distribution.Descriptor, error)
 	TarSplitReader(ChainID) (io.ReadCloser, error)
 
 	SetMountID(string, string) error

layer/layer_store.go

@@ -8,6 +8,7 @@ import (
 	"sync"
 
 	"github.com/Sirupsen/logrus"
+	"github.com/docker/distribution"
 	"github.com/docker/distribution/digest"
 	"github.com/docker/docker/daemon/graphdriver"
 	"github.com/docker/docker/pkg/archive"
@@ -137,6 +138,13 @@ func (ls *layerStore) loadLayer(layer ChainID) (*roLayer, error) {
 		references: map[Layer]struct{}{},
 	}
 
+	foreignSrc, err := ls.store.GetForeignSource(layer)
+	if err == nil {
+		cl.foreignSrc = &foreignSrc
+	} else if err != ErrNoForeignSource {
+		return nil, fmt.Errorf("failed to get foreign reference for %s: %s", layer, err)
+	}
+
 	if parent != "" {
 		p, err := ls.loadLayer(parent)
 		if err != nil {
@@ -228,6 +236,10 @@ func (ls *layerStore) applyTar(tx MetadataTransaction, ts io.Reader, parent stri
 }
 
 func (ls *layerStore) Register(ts io.Reader, parent ChainID) (Layer, error) {
+	return ls.RegisterForeign(ts, parent, nil)
+}
+
+func (ls *layerStore) RegisterForeign(ts io.Reader, parent ChainID, foreignSrc *distribution.Descriptor) (Layer, error) {
 	// err is used to hold the error which will always trigger
 	// cleanup of creates sources but may not be an error returned
 	// to the caller (already exists).
@@ -258,6 +270,7 @@ func (ls *layerStore) Register(ts io.Reader, parent ChainID) (Layer, error) {
 	layer := &roLayer{
 		parent:         p,
 		cacheID:        stringid.GenerateRandomID(),
+		foreignSrc:     foreignSrc,
 		referenceCount: 1,
 		layerStore:     ls,
 		references:     map[Layer]struct{}{},

layer/layer_unix.go

@@ -7,3 +7,9 @@ import "github.com/docker/docker/pkg/stringid"
 func (ls *layerStore) mountID(name string) string {
 	return stringid.GenerateRandomID()
 }
+
+// ForeignSourceSupported returns whether layers downloaded from foreign sources are
+// supported in this daemon.
+func ForeignSourceSupported() bool {
+	return false
+}

layer/layer_windows.go

@@ -96,3 +96,9 @@ func (ls *layerStore) mountID(name string) string {
 func (ls *layerStore) GraphDriver() graphdriver.Driver {
 	return ls.driver
 }
+
+// ForeignSourceSupported returns whether layers downloaded from foreign sources are
+// supported in this daemon.
+func ForeignSourceSupported() bool {
+	return true
+}

layer/ro_layer.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/docker/distribution"
 	"github.com/docker/distribution/digest"
 )
 
@@ -14,6 +15,7 @@ type roLayer struct {
 	cacheID    string
 	size       int64
 	layerStore *layerStore
+	foreignSrc *distribution.Descriptor
 
 	referenceCount int
 	references     map[Layer]struct{}
@@ -123,6 +125,11 @@ func storeLayer(tx MetadataTransaction, layer *roLayer) error {
 			return err
 		}
 	}
+	if layer.foreignSrc != nil {
+		if err := tx.SetForeignSource(*layer.foreignSrc); err != nil {
+			return err
+		}
+	}
 
 	return nil
 }

layer/ro_layer_windows.go

@@ -0,0 +1,9 @@
+package layer
+
+import "github.com/docker/distribution"
+
+var _ ForeignSourcer = &roLayer{}
+
+func (rl *roLayer) ForeignSource() *distribution.Descriptor {
+	return rl.foreignSrc
+}

vendor/src/github.com/docker/distribution/AUTHORS

@@ -1,4 +1,5 @@
 Aaron Lehmann <aaron.lehmann@docker.com>
+Aaron Schlesinger <aschlesinger@deis.com>
 Aaron Vinson <avinson.public@gmail.com>
 Adam Enger <adamenger@gmail.com>
 Adrian Mouat <adrian.mouat@gmail.com>
@@ -7,13 +8,16 @@ Alex Chan <alex.chan@metaswitch.com>
 Alex Elman <aelman@indeed.com>
 amitshukla <ashukla73@hotmail.com>
 Amy Lindburg <amy.lindburg@docker.com>
+Andrew Hsu <andrewhsu@acm.org>
 Andrew Meredith <andymeredith@gmail.com>
 Andrew T Nguyen <andrew.nguyen@docker.com>
 Andrey Kostov <kostov.andrey@gmail.com>
 Andy Goldstein <agoldste@redhat.com>
+Anis Elleuch <vadmeste@gmail.com>
 Anton Tiurin <noxiouz@yandex.ru>
 Antonio Mercado <amercado@thinknode.com>
 Antonio Murdaca <runcom@redhat.com>
+Arien Holthuizen <aholthuizen@schubergphilis.com>
 Arnaud Porterie <arnaud.porterie@docker.com>
 Arthur Baars <arthur@semmle.com>
 Asuka Suzuki <hello@tanksuzuki.com>
@@ -27,6 +31,7 @@ burnettk <burnettk@gmail.com>
 Carson A <ca@carsonoid.net>
 Chris Dillon <squarism@gmail.com>
 Daisuke Fujita <dtanshi45@gmail.com>
+Daniel Huhn <daniel@danielhuhn.de>
 Darren Shepherd <darren@rancher.com>
 Dave Trombley <dave.trombley@gmail.com>
 Dave Tucker <dt@docker.com>
@@ -41,6 +46,7 @@ DJ Enriquez <dj.enriquez@infospace.com>
 Donald Huang <don.hcd@gmail.com>
 Doug Davis <dug@us.ibm.com>
 Eric Yang <windfarer@gmail.com>
+Fabio Huser <fabio@fh1.ch>
 farmerworking <farmerworking@gmail.com>
 Felix Yan <felixonmars@archlinux.org>
 Florentin Raud <florentin.raud@gmail.com>
@@ -57,8 +63,10 @@ Jack Griffin <jackpg14@gmail.com>
 Jason Freidman <jason.freidman@gmail.com>
 Jeff Nickoloff <jeff@allingeek.com>
 Jessie Frazelle <jessie@docker.com>
+jhaohai <jhaohai@foxmail.com>
 Jianqing Wang <tsing@jianqing.org>
 John Starks <jostarks@microsoft.com>
+Jon Johnson <jonjohnson@google.com>
 Jon Poler <jonathan.poler@apcera.com>
 Jonathan Boulle <jonathanboulle@gmail.com>
 Jordan Liggitt <jliggitt@redhat.com>
@@ -92,17 +100,20 @@ Olivier Gambier <olivier@docker.com>
 Olivier Jacques <olivier.jacques@hp.com>
 Omer Cohen <git@omer.io>
 Patrick Devine <patrick.devine@docker.com>
+Phil Estes <estesp@linux.vnet.ibm.com>
 Philip Misiowiec <philip@atlashealth.com>
 Richard Scothern <richard.scothern@docker.com>
 Rodolfo Carvalho <rhcarvalho@gmail.com>
 Rusty Conover <rusty@luckydinosaur.com>
 Sean Boran <Boran@users.noreply.github.com>
 Sebastiaan van Stijn <github@gone.nl>
+Serge Dubrouski <sergeyfd@gmail.com>
 Sharif Nassar <sharif@mrwacky.com>
 Shawn Falkner-Horine <dreadpirateshawn@gmail.com>
 Shreyas Karnik <karnik.shreyas@gmail.com>
 Simon Thulbourn <simon+github@thulbourn.com>
 Spencer Rinehart <anubis@overthemonkey.com>
+Stefan Majewsky <stefan.majewsky@sap.com>
 Stefan Weil <sw@weilnetz.de>
 Stephen J Day <stephen.day@docker.com>
 Sungho Moon <sungho.moon@navercorp.com>
@@ -114,6 +125,7 @@ Thomas Sjögren <konstruktoid@users.noreply.github.com>
 Tianon Gravi <admwiggin@gmail.com>
 Tibor Vass <teabee89@gmail.com>
 Tonis Tiigi <tonistiigi@gmail.com>
+Tony Holdstock-Brown <tony@docker.com>
 Trevor Pounds <trevor.pounds@gmail.com>
 Troels Thomsen <troels@thomsen.io>
 Vincent Batts <vbatts@redhat.com>

vendor/src/github.com/docker/distribution/Dockerfile

@@ -1,8 +1,4 @@
-FROM golang:1.6
+FROM golang:1.6-alpine
-
-RUN apt-get update && \
-    apt-get install -y apache2-utils && \
-    rm -rf /var/lib/apt/lists/*
 
 ENV DISTRIBUTION_DIR /go/src/github.com/docker/distribution
 ENV DOCKER_BUILDTAGS include_oss include_gcs
@@ -10,6 +6,10 @@ ENV DOCKER_BUILDTAGS include_oss include_gcs
 WORKDIR $DISTRIBUTION_DIR
 COPY . $DISTRIBUTION_DIR
 COPY cmd/registry/config-dev.yml /etc/docker/registry/config.yml
+
+RUN set -ex \
+    && apk add --no-cache make git
+
 RUN make PREFIX=/go clean binaries
 
 VOLUME ["/var/lib/registry"]

vendor/src/github.com/docker/distribution/blobs.go

@@ -69,6 +69,9 @@ type Descriptor struct {
 	// against against this digest.
 	Digest digest.Digest `json:"digest,omitempty"`
 
+	// URLs contains the source URLs of this content.
+	URLs []string `json:"urls,omitempty"`
+
 	// NOTE: Before adding a field here, please ensure that all
 	// other options have been exhausted. Much of the type relationships
 	// depend on the simplicity of this type.

vendor/src/github.com/docker/distribution/manifest/schema2/manifest.go

@@ -20,6 +20,10 @@ const (
 	// MediaTypeLayer is the mediaType used for layers referenced by the
 	// manifest.
 	MediaTypeLayer = "application/vnd.docker.image.rootfs.diff.tar.gzip"
+
+	// MediaTypeForeignLayer is the mediaType used for layers that must be
+	// downloaded from foreign URLs.
+	MediaTypeForeignLayer = "application/vnd.docker.image.rootfs.foreign.diff.tar.gzip"
 )
 
 var (
@@ -63,7 +67,6 @@ type Manifest struct {
 // References returnes the descriptors of this manifests references.
 func (m Manifest) References() []distribution.Descriptor {
 	return m.Layers
-
 }
 
 // Target returns the target of this signed manifest.