Merge pull request #909 from vburenin/diff-plugin

Make Diff/Apply plugable

plugin/differ.go

@@ -0,0 +1,12 @@
+package plugin
+
+import (
+	"github.com/containerd/containerd/mount"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"golang.org/x/net/context"
+)
+
+type Differ interface {
+	Apply(ctx context.Context, desc ocispec.Descriptor, mount []mount.Mount) (ocispec.Descriptor, error)
+	DiffMounts(ctx context.Context, lower, upper []mount.Mount, media, ref string) (ocispec.Descriptor, error)
+}

plugin/plugin.go

@@ -19,6 +19,7 @@ const (
 	GRPCPlugin
 	SnapshotPlugin
 	TaskMonitorPlugin
+	DiffPlugin
 )
 
 type Registration struct {
@@ -35,6 +36,7 @@ type InitContext struct {
 	Content     content.Store
 	Meta        *bolt.DB
 	Snapshotter snapshot.Snapshotter
+	Differ      Differ
 	Config      interface{}
 	Context     context.Context
 	Monitor     TaskMonitor