@@ -75,7 +75,7 @@ func (s *fs) Walk(f DigestWalkFunc) error {

 	for _, v := range dir {

 		dgst := digest.NewDigestFromHex(string(digest.Canonical), v.Name())

 		if err := dgst.Validate(); err != nil {

-			logrus.Debugf("Skipping invalid digest %s: %s", dgst, err)

+			logrus.Debugf("skipping invalid digest %s: %s", dgst, err)

 			continue

 		}

 		if err := f(dgst); err != nil {

@@ -113,7 +113,7 @@ func (s *fs) Set(data []byte) (digest.Digest, error) {

 	defer s.Unlock()

 	if len(data) == 0 {

-		return "", fmt.Errorf("Invalid empty data")

+		return "", fmt.Errorf("invalid empty data")

 	}

 	dgst := digest.FromBytes(data)

@@ -52,7 +52,7 @@ func TestFSGetInvalidData(t *testing.T) {

 	_, err = fs.Get(id)

 	if err == nil {

-		t.Fatal("Expected get to fail after data modification.")

+		t.Fatal("expected get to fail after data modification.")

 	}

 }

@@ -75,7 +75,7 @@ func TestFSInvalidSet(t *testing.T) {

 	_, err = fs.Set([]byte("foobar"))

 	if err == nil {

-		t.Fatal("Expecting error from invalid filesystem data.")

+		t.Fatal("expected error from invalid filesystem data.")

 	}

 }

@@ -109,7 +109,7 @@ func TestFSInvalidRoot(t *testing.T) {

 		_, err = NewFSStoreBackend(root)

 		if err == nil {

-			t.Fatalf("Expected error from root %q and invlid file %q", tc.root, tc.invalidFile)

+			t.Fatalf("expected error from root %q and invalid file %q", tc.root, tc.invalidFile)

 		}

 		os.RemoveAll(root)

@@ -154,18 +154,18 @@ func testMetadataGetSet(t *testing.T, store StoreBackend) {

 	_, err = store.GetMetadata(id2, "tkey2")

 	if err == nil {

-		t.Fatal("Expected error for getting metadata for unknown key")

+		t.Fatal("expected error for getting metadata for unknown key")

 	}

 	id3 := digest.FromBytes([]byte("baz"))

 	err = store.SetMetadata(id3, "tkey", []byte("tval"))

 	if err == nil {

-		t.Fatal("Expected error for setting metadata for unknown ID.")

+		t.Fatal("expected error for setting metadata for unknown ID.")

 	}

 	_, err = store.GetMetadata(id3, "tkey")

 	if err == nil {

-		t.Fatal("Expected error for getting metadata for unknown ID.")

+		t.Fatal("expected error for getting metadata for unknown ID.")

 	}

 }

@@ -234,16 +234,16 @@ func TestFSInvalidWalker(t *testing.T) {

 	n := 0

 	err = fs.Walk(func(id digest.Digest) error {

 		if id != fooID {

-			t.Fatalf("Invalid walker ID %q, expected %q", id, fooID)

+			t.Fatalf("invalid walker ID %q, expected %q", id, fooID)

 		}

 		n++

 		return nil

 	})

 	if err != nil {

-		t.Fatalf("Invalid data should not have caused walker error, got %v", err)

+		t.Fatalf("invalid data should not have caused walker error, got %v", err)

 	}

 	if n != 1 {

-		t.Fatalf("Expected 1 walk initialization, got %d", n)

+		t.Fatalf("expected 1 walk initialization, got %d", n)

 	}

 }

@@ -261,7 +261,7 @@ func testGetSet(t *testing.T, store StoreBackend) {

 	if err != nil {

 		t.Fatal(err)

 	}

-	// skipping use of digest pkg because its used by the implementation

+	// skipping use of digest pkg because it is used by the implementation

 	h := sha256.New()

 	_, err = h.Write(randomInput)

 	if err != nil {

@@ -278,14 +278,14 @@ func testGetSet(t *testing.T, store StoreBackend) {

 			t.Fatal(err)

 		}

 		if id != tc.expected {

-			t.Fatalf("Expected ID %q, got %q", tc.expected, id)

+			t.Fatalf("expected ID %q, got %q", tc.expected, id)

 		}

 	}

 	for _, emptyData := range [][]byte{nil, {}} {

 		_, err := store.Set(emptyData)

 		if err == nil {

-			t.Fatal("Expected error for nil input.")

+			t.Fatal("expected error for nil input.")

 		}

 	}

@@ -295,14 +295,14 @@ func testGetSet(t *testing.T, store StoreBackend) {

 			t.Fatal(err)

 		}

 		if bytes.Compare(data, tc.input) != 0 {

-			t.Fatalf("Expected data %q, got %q", tc.input, data)

+			t.Fatalf("expected data %q, got %q", tc.input, data)

 		}

 	}

 	for _, key := range []digest.Digest{"foobar:abc", "sha256:abc", "sha256:c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2a"} {

 		_, err := store.Get(key)

 		if err == nil {

-			t.Fatalf("Expected error for ID %q.", key)

+			t.Fatalf("expected error for ID %q.", key)

 		}

 	}

@@ -325,7 +325,7 @@ func testDelete(t *testing.T, store StoreBackend) {

 	_, err = store.Get(id)

 	if err == nil {

-		t.Fatalf("Expected getting deleted item %q to fail", id)

+		t.Fatalf("expected getting deleted item %q to fail", id)

 	}

 	_, err = store.Get(id2)

 	if err != nil {

@@ -338,7 +338,7 @@ func testDelete(t *testing.T, store StoreBackend) {

 	}

 	_, err = store.Get(id2)

 	if err == nil {

-		t.Fatalf("Expected getting deleted item %q to fail", id2)

+		t.Fatalf("expected getting deleted item %q to fail", id2)

 	}

 }

@@ -366,10 +366,10 @@ func testWalker(t *testing.T, store StoreBackend) {

 	}

 	if n != 2 {

-		t.Fatalf("Expected 2 walk initializations, got %d", n)

+		t.Fatalf("expected 2 walk initializations, got %d", n)

 	}

 	if len(tcases) != 0 {

-		t.Fatalf("Expected empty unwalked set, got %+v", tcases)

+		t.Fatalf("expected empty unwalked set, got %+v", tcases)

 	}

 	// stop on error

@@ -379,6 +379,6 @@ func testWalker(t *testing.T, store StoreBackend) {

 		return errors.New("")

 	})

 	if err == nil {

-		t.Fatalf("Exected error from walker.")

+		t.Fatalf("expected error from walker.")

 	}

 }

@@ -29,21 +29,21 @@ func IDFromDigest(digest digest.Digest) ID {

 // V1Image stores the V1 image configuration.

 type V1Image struct {

-	// ID a unique 64 character identifier of the image

+	// ID is a unique 64 character identifier of the image

 	ID string `json:"id,omitempty"`

-	// Parent id of the image

+	// Parent is the ID of the parent image

 	Parent string `json:"parent,omitempty"`

-	// Comment user added comment

+	// Comment is the commit message that was set when committing the image

 	Comment string `json:"comment,omitempty"`

-	// Created timestamp when image was created

+	// Created is the timestamp at which the image was created

 	Created time.Time `json:"created"`

 	// Container is the id of the container used to commit

 	Container string `json:"container,omitempty"`

 	// ContainerConfig is the configuration of the container that is committed into the image

 	ContainerConfig container.Config `json:"container_config,omitempty"`

-	// DockerVersion specifies version on which image is built

+	// DockerVersion specifies the version of Docker that was used to build the image

 	DockerVersion string `json:"docker_version,omitempty"`

-	// Author of the image

+	// Author is the name of the author that was specified when committing the image

 	Author string `json:"author,omitempty"`

 	// Config is the configuration of the container received from the client

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

@@ -112,13 +112,13 @@ func (img *Image) MarshalJSON() ([]byte, error) {

 // History stores build commands that were used to create an image

 type History struct {

-	// Created timestamp for build point

+	// Created is the timestamp at which the image was created

 	Created time.Time `json:"created"`

-	// Author of the build point

+	// Author is the name of the author that was specified when committing the image

 	Author string `json:"author,omitempty"`

-	// CreatedBy keeps the Dockerfile command used while building image.

+	// CreatedBy keeps the Dockerfile command used while building the image

 	CreatedBy string `json:"created_by,omitempty"`

-	// Comment is custom message set by the user when creating the image.

+	// Comment is the commit message that was set when committing the image

 	Comment string `json:"comment,omitempty"`

 	// EmptyLayer is set to true if this history item did not generate a

 	// layer. Otherwise, the history item is associated with the next

@@ -126,7 +126,7 @@ type History struct {

 	EmptyLayer bool `json:"empty_layer,omitempty"`

 }

-// Exporter provides interface for exporting and importing images

+// Exporter provides interface for loading and saving images

 type Exporter interface {

 	Load(io.ReadCloser, io.Writer, bool) error

 	// TODO: Load(net.Context, io.ReadCloser, <- chan StatusMessage) error

@@ -141,7 +141,7 @@ func NewFromJSON(src []byte) (*Image, error) {

 		return nil, err

 	}

 	if img.RootFS == nil {

-		return nil, errors.New("Invalid image JSON, no RootFS key.")

+		return nil, errors.New("invalid image JSON, no RootFS key")

 	}

 	img.rawJSON = src

@@ -24,14 +24,14 @@ func TestJSON(t *testing.T) {

 	}

 	rawJSON := img.RawJSON()

 	if string(rawJSON) != sampleImageJSON {

-		t.Fatalf("Raw JSON of config didn't match: expected %+v, got %v", sampleImageJSON, rawJSON)

+		t.Fatalf("raw JSON of config didn't match: expected %+v, got %v", sampleImageJSON, rawJSON)

 	}

 }

 func TestInvalidJSON(t *testing.T) {

 	_, err := NewFromJSON([]byte("{}"))

 	if err == nil {

-		t.Fatal("Expected JSON parse error")

+		t.Fatal("expected JSON parse error")

 	}

 }

@@ -36,7 +36,7 @@ type LogImageEvent interface {

 	LogImageEvent(imageID, refName, action string)

 }

-// NewTarExporter returns new ImageExporter for tar packages

+// NewTarExporter returns new Exporter for tar packages

 func NewTarExporter(is image.Store, ls layer.Store, rs reference.Store, loggerImgEvent LogImageEvent) image.Exporter {

 	return &tarexporter{

 		is:             is,