@@ -63,7 +63,10 @@ func (s *TagStore) newManifest(localName, remoteName, tag string) ([]byte, error

 			}

 		}

-		checksum := layer.Checksum

+		checksum, err := layer.GetCheckSum(s.graph.ImageRoot(layer.ID))

+		if err != nil {

+			return nil, fmt.Errorf("Error getting image checksum: %s", err)

+		}

 		if tarsum.VersionLabelForChecksum(checksum) != tarsum.Version1.String() {

 			archive, err := layer.TarLayer()

 			if err != nil {

@@ -79,6 +82,11 @@ func (s *TagStore) newManifest(localName, remoteName, tag string) ([]byte, error

 			}

 			checksum = tarSum.Sum(nil)

+

+			// Save checksum value

+			if err := layer.SaveCheckSum(s.graph.ImageRoot(layer.ID), checksum); err != nil {

+				return nil, err

+			}

 		}

 		jsonData, err := layer.RawJson()

new file mode 100644

@@ -0,0 +1,82 @@

+package graph

+

+import (

+	"encoding/json"

+	"os"

+	"testing"

+

+	"github.com/docker/docker/image"

+	"github.com/docker/docker/registry"

+	"github.com/docker/docker/utils"

+)

+

+const (

+	testManifestImageName    = "testapp"

+	testManifestImageID      = "d821b739e8834ec89ac4469266c3d11515da88fdcbcbdddcbcddb636f54fdde9"

+	testManifestImageIDShort = "d821b739e883"

+	testManifestTag          = "manifesttest"

+)

+

+func TestManifestTarsumCache(t *testing.T) {

+	tmp, err := utils.TestDirectory("")

+	if err != nil {

+		t.Fatal(err)

+	}

+	defer os.RemoveAll(tmp)

+	store := mkTestTagStore(tmp, t)

+	defer store.graph.driver.Cleanup()

+

+	archive, err := fakeTar()

+	if err != nil {

+		t.Fatal(err)

+	}

+	img := &image.Image{ID: testManifestImageID}

+	if err := store.graph.Register(img, archive); err != nil {

+		t.Fatal(err)

+	}

+	if err := store.Set(testManifestImageName, testManifestTag, testManifestImageID, false); err != nil {

+		t.Fatal(err)

+	}

+

+	if cs, err := img.GetCheckSum(store.graph.ImageRoot(testManifestImageID)); err != nil {

+		t.Fatal(err)

+	} else if cs != "" {

+		t.Fatalf("Non-empty checksum file after register")

+	}

+

+	// Generate manifest

+	payload, err := store.newManifest(testManifestImageName, testManifestImageName, testManifestTag)

+	if err != nil {

+		t.Fatal(err)

+	}

+

+	manifestChecksum, err := img.GetCheckSum(store.graph.ImageRoot(testManifestImageID))

+	if err != nil {

+		t.Fatal(err)

+	}

+

+	var manifest registry.ManifestData

+	if err := json.Unmarshal(payload, &manifest); err != nil {

+		t.Fatalf("error unmarshalling manifest: %s", err)

+	}

+

+	if len(manifest.FSLayers) != 1 {

+		t.Fatalf("Unexpected number of layers, expecting 1: %d", len(manifest.FSLayers))

+	}

+

+	if manifest.FSLayers[0].BlobSum != manifestChecksum {

+		t.Fatalf("Unexpected blob sum, expecting %q, got %q", manifestChecksum, manifest.FSLayers[0].BlobSum)

+	}

+

+	if len(manifest.History) != 1 {

+		t.Fatalf("Unexpected number of layer history, expecting 1: %d", len(manifest.History))

+	}

+

+	v1compat, err := img.RawJson()

+	if err != nil {

+		t.Fatal(err)

+	}

+	if manifest.History[0].V1Compatibility != string(v1compat) {

+		t.Fatalf("Unexpected json value\nExpected:\n%s\nActual:\n%s", v1compat, manifest.History[0].V1Compatibility)

+	}

+}

@@ -150,7 +150,6 @@ func (s *TagStore) CmdLookup(job *engine.Job) engine.Status {

 		out.Set("Os", image.OS)

 		out.SetInt64("Size", image.Size)

 		out.SetInt64("VirtualSize", image.GetParentsSize(0)+image.Size)

-		out.Set("Checksum", image.Checksum)

 		if _, err = out.WriteTo(job.Stdout); err != nil {

 			return job.Error(err)

 		}

@@ -31,7 +31,6 @@ type Image struct {

 	Config          *runconfig.Config `json:"config,omitempty"`

 	Architecture    string            `json:"architecture,omitempty"`

 	OS              string            `json:"os,omitempty"`

-	Checksum        string            `json:"checksum"`

 	Size            int64

 	graph Graph

@@ -114,6 +113,24 @@ func (img *Image) SaveSize(root string) error {

 	return nil

 }

+func (img *Image) SaveCheckSum(root, checksum string) error {

+	if err := ioutil.WriteFile(path.Join(root, "checksum"), []byte(checksum), 0600); err != nil {

+		return fmt.Errorf("Error storing checksum in %s/checksum: %s", root, err)

+	}

+	return nil

+}

+

+func (img *Image) GetCheckSum(root string) (string, error) {

+	cs, err := ioutil.ReadFile(path.Join(root, "checksum"))

+	if err != nil {

+		if os.IsNotExist(err) {

+			return "", nil

+		}

+		return "", err

+	}

+	return string(cs), err

+}

+

 func jsonPath(root string) string {

 	return path.Join(root, "json")

 }