Implementation of the Manifest Service API refactor.

Add a generic Manifest interface to represent manifests in the registry and
remove references to schema specific manifests.

Add a ManifestBuilder to construct Manifest objects. Concrete manifest builders
will exist for each manifest type and implementations will contain manifest
specific data used to build a manifest.

Remove Signatures() from Repository interface.

Signatures are relevant only to schema1 manifests.  Move access to the signature
store inside the schema1 manifestStore.  Add some API tests to verify
signature roundtripping.

schema1
-------

Change the way data is stored in schema1.Manifest to enable Payload() to be used
to return complete Manifest JSON from the HTTP handler without knowledge of the
schema1 protocol.

tags
----

Move tag functionality to a seperate TagService and update ManifestService
to use the new interfaces.  Implement a driver based tagService to be backward
compatible with the current tag service.

Add a proxyTagService to enable the registry to get a digest for remote manifests
from a tag.

manifest store
--------------

Remove revision store and move all signing functionality into the signed manifeststore.

manifest registration
---------------------

Add a mechanism to register manifest media types and to allow different manifest
types to be Unmarshalled correctly.

client
------

Add ManifestServiceOptions to client functions to allow tags to be passed into Put and
Get for building correct registry URLs.  Change functional arguments to be an interface type
to allow passing data without mutating shared state.

Signed-off-by: Richard Scothern <richard.scothern@gmail.com>

Signed-off-by: Richard Scothern <richard.scothern@docker.com>

registry.go

@@ -2,8 +2,6 @@ package distribution
 
 import (
 	"github.com/docker/distribution/context"
-	"github.com/docker/distribution/digest"
-	"github.com/docker/distribution/manifest/schema1"
 )
 
 // Scope defines the set of items that match a namespace.
@@ -44,7 +42,9 @@ type Namespace interface {
 }
 
 // ManifestServiceOption is a function argument for Manifest Service methods
-type ManifestServiceOption func(ManifestService) error
+type ManifestServiceOption interface {
+	Apply(ManifestService) error
+}
 
 // Repository is a named collection of manifests and layers.
 type Repository interface {
@@ -62,59 +62,10 @@ type Repository interface {
 	// be a BlobService for use with clients. This will allow such
 	// implementations to avoid implementing ServeBlob.
 
-	// Signatures returns a reference to this repository's signatures service.
-	Signatures() SignatureService
+	// Tags returns a reference to this repositories tag service
+	Tags(ctx context.Context) TagService
 }
 
 // TODO(stevvooe): Must add close methods to all these. May want to change the
 // way instances are created to better reflect internal dependency
 // relationships.
-
-// ManifestService provides operations on image manifests.
-type ManifestService interface {
-	// Exists returns true if the manifest exists.
-	Exists(dgst digest.Digest) (bool, error)
-
-	// Get retrieves the identified by the digest, if it exists.
-	Get(dgst digest.Digest) (*schema1.SignedManifest, error)
-
-	// Delete removes the manifest, if it exists.
-	Delete(dgst digest.Digest) error
-
-	// Put creates or updates the manifest.
-	Put(manifest *schema1.SignedManifest) error
-
-	// TODO(stevvooe): The methods after this message should be moved to a
-	// discrete TagService, per active proposals.
-
-	// Tags lists the tags under the named repository.
-	Tags() ([]string, error)
-
-	// ExistsByTag returns true if the manifest exists.
-	ExistsByTag(tag string) (bool, error)
-
-	// GetByTag retrieves the named manifest, if it exists.
-	GetByTag(tag string, options ...ManifestServiceOption) (*schema1.SignedManifest, error)
-
-	// TODO(stevvooe): There are several changes that need to be done to this
-	// interface:
-	//
-	//	1. Allow explicit tagging with Tag(digest digest.Digest, tag string)
-	//	2. Support reading tags with a re-entrant reader to avoid large
-	//       allocations in the registry.
-	//	3. Long-term: Provide All() method that lets one scroll through all of
-	//       the manifest entries.
-	//	4. Long-term: break out concept of signing from manifests. This is
-	//       really a part of the distribution sprint.
-	//	5. Long-term: Manifest should be an interface. This code shouldn't
-	//       really be concerned with the storage format.
-}
-
-// SignatureService provides operations on signatures.
-type SignatureService interface {
-	// Get retrieves all of the signature blobs for the specified digest.
-	Get(dgst digest.Digest) ([][]byte, error)
-
-	// Put stores the signature for the provided digest.
-	Put(dgst digest.Digest, signatures ...[]byte) error
-}