Merge master into breakout_swarm

Signed-off-by: Alex Ellis <alexellis2@gmail.com>

gateway/vendor/github.com/docker/distribution/manifest/schema2/builder.go

@@ -0,0 +1,80 @@
+package schema2
+
+import (
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+	"github.com/docker/distribution/digest"
+)
+
+// builder is a type for constructing manifests.
+type builder struct {
+	// bs is a BlobService used to publish the configuration blob.
+	bs distribution.BlobService
+
+	// configJSON references
+	configJSON []byte
+
+	// layers is a list of layer descriptors that gets built by successive
+	// calls to AppendReference.
+	layers []distribution.Descriptor
+}
+
+// NewManifestBuilder is used to build new manifests for the current schema
+// version. It takes a BlobService so it can publish the configuration blob
+// as part of the Build process.
+func NewManifestBuilder(bs distribution.BlobService, configJSON []byte) distribution.ManifestBuilder {
+	mb := &builder{
+		bs:         bs,
+		configJSON: make([]byte, len(configJSON)),
+	}
+	copy(mb.configJSON, configJSON)
+
+	return mb
+}
+
+// Build produces a final manifest from the given references.
+func (mb *builder) Build(ctx context.Context) (distribution.Manifest, error) {
+	m := Manifest{
+		Versioned: SchemaVersion,
+		Layers:    make([]distribution.Descriptor, len(mb.layers)),
+	}
+	copy(m.Layers, mb.layers)
+
+	configDigest := digest.FromBytes(mb.configJSON)
+
+	var err error
+	m.Config, err = mb.bs.Stat(ctx, configDigest)
+	switch err {
+	case nil:
+		// Override MediaType, since Put always replaces the specified media
+		// type with application/octet-stream in the descriptor it returns.
+		m.Config.MediaType = MediaTypeConfig
+		return FromStruct(m)
+	case distribution.ErrBlobUnknown:
+		// nop
+	default:
+		return nil, err
+	}
+
+	// Add config to the blob store
+	m.Config, err = mb.bs.Put(ctx, MediaTypeConfig, mb.configJSON)
+	// Override MediaType, since Put always replaces the specified media
+	// type with application/octet-stream in the descriptor it returns.
+	m.Config.MediaType = MediaTypeConfig
+	if err != nil {
+		return nil, err
+	}
+
+	return FromStruct(m)
+}
+
+// AppendReference adds a reference to the current ManifestBuilder.
+func (mb *builder) AppendReference(d distribution.Describable) error {
+	mb.layers = append(mb.layers, d.Descriptor())
+	return nil
+}
+
+// References returns the current references added to this builder.
+func (mb *builder) References() []distribution.Descriptor {
+	return mb.layers
+}