Move manifest package to schema1

As we begin our march towards multi-arch, we must prepare for the reality of
multiple manifest schemas. This is the beginning of a set of changes to
facilitate this. We are both moving this package into its target position where
it may live peacefully next to other manfiest versions.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

manifest/doc.go

@@ -0,0 +1 @@
+package manifest

manifest/schema1/manifest.go

@@ -1,9 +1,10 @@
-package manifest
+package schema1
 
 import (
 	"encoding/json"
 
 	"github.com/docker/distribution/digest"
+	"github.com/docker/distribution/manifest"
 	"github.com/docker/libtrust"
 )
 
@@ -17,18 +18,18 @@ const (
 	ManifestMediaType = "application/vnd.docker.distribution.manifest.v1+json"
 )
 
-// Versioned provides a struct with just the manifest schemaVersion. Incoming
-// content with unknown schema version can be decoded against this struct to
-// check the version.
-type Versioned struct {
-	// SchemaVersion is the image manifest schema that this image follows
-	SchemaVersion int `json:"schemaVersion"`
-}
+var (
+	// SchemaVersion provides a pre-initialized version structure for this
+	// packages version of the manifest.
+	SchemaVersion = manifest.Versioned{
+		SchemaVersion: 1,
+	}
+)
 
 // Manifest provides the base accessible fields for working with V2 image
 // format in the registry.
 type Manifest struct {
-	Versioned
+	manifest.Versioned
 
 	// Name is the name of the image's repository
 	Name string `json:"name"`

manifest/schema1/manifest_test.go

@@ -1,4 +1,4 @@
-package manifest
+package schema1
 
 import (
 	"bytes"
@@ -80,11 +80,9 @@ func genEnv(t *testing.T) *testEnv {
 	name, tag := "foo/bar", "test"
 
 	m := Manifest{
-		Versioned: Versioned{
-			SchemaVersion: 1,
-		},
-		Name: name,
-		Tag:  tag,
+		Versioned: SchemaVersion,
+		Name:      name,
+		Tag:       tag,
 		FSLayers: []FSLayer{
 			{
 				BlobSum: "asdf",

manifest/schema1/sign.go

@@ -1,4 +1,4 @@
-package manifest
+package schema1
 
 import (
 	"crypto/x509"

manifest/schema1/verify.go

@@ -1,4 +1,4 @@
-package manifest
+package schema1
 
 import (
 	"crypto/x509"

manifest/versioned.go

@@ -0,0 +1,9 @@
+package manifest
+
+// Versioned provides a struct with just the manifest schemaVersion. Incoming
+// content with unknown schema version can be decoded against this struct to
+// check the version.
+type Versioned struct {
+	// SchemaVersion is the image manifest schema that this image follows
+	SchemaVersion int `json:"schemaVersion"`
+}