Merge pull request #909 from vburenin/diff-plugin

Make Diff/Apply plugable

services/diff/client.go

@@ -54,6 +54,14 @@ func (r *remote) DiffMounts(ctx context.Context, a, b []mount.Mount, media, ref
 	return toDescriptor(resp.Diff), nil
 }
 
+func toDescriptor(d *descriptor.Descriptor) ocispec.Descriptor {
+	return ocispec.Descriptor{
+		MediaType: d.MediaType,
+		Digest:    d.Digest,
+		Size:      d.Size_,
+	}
+}
+
 func fromDescriptor(d ocispec.Descriptor) *descriptor.Descriptor {
 	return &descriptor.Descriptor{
 		MediaType: d.MediaType,

services/diff/service.go

@@ -1,22 +1,10 @@
 package diff
 
 import (
-	"io"
-	"io/ioutil"
-	"os"
-
 	diffapi "github.com/containerd/containerd/api/services/diff"
-	"github.com/containerd/containerd/api/types/descriptor"
 	mounttypes "github.com/containerd/containerd/api/types/mount"
-	"github.com/containerd/containerd/archive"
-	"github.com/containerd/containerd/archive/compression"
-	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/mount"
 	"github.com/containerd/containerd/plugin"
-	"github.com/containerd/containerd/snapshot"
-	digest "github.com/opencontainers/go-digest"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-	"github.com/pkg/errors"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
@@ -25,21 +13,15 @@ func init() {
 	plugin.Register("diff-grpc", &plugin.Registration{
 		Type: plugin.GRPCPlugin,
 		Init: func(ic *plugin.InitContext) (interface{}, error) {
-			return newService(ic.Content, ic.Snapshotter)
+			return &service{
+				diff: ic.Differ,
+			}, nil
 		},
 	})
 }
 
 type service struct {
-	store       content.Store
-	snapshotter snapshot.Snapshotter
-}
-
-func newService(store content.Store, snapshotter snapshot.Snapshotter) (*service, error) {
-	return &service{
-		store:       store,
-		snapshotter: snapshotter,
-	}, nil
+	diff plugin.Differ
 }
 
 func (s *service) Register(gs *grpc.Server) error {
@@ -53,143 +35,31 @@ func (s *service) Apply(ctx context.Context, er *diffapi.ApplyRequest) (*diffapi
 
 	mounts := toMounts(er.Mounts)
 
-	dir, err := ioutil.TempDir("", "extract-")
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to create temporary directory")
-	}
-	defer os.RemoveAll(dir)
-
-	if err := mount.MountAll(mounts, dir); err != nil {
-		return nil, errors.Wrap(err, "failed to mount")
-	}
-	defer mount.Unmount(dir, 0)
-
-	r, err := s.store.Reader(ctx, desc.Digest)
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to get reader from content store")
-	}
-	defer r.Close()
-
-	// TODO: only decompress stream if media type is compressed
-	ds, err := compression.DecompressStream(r)
+	ocidesc, err := s.diff.Apply(ctx, desc, mounts)
 	if err != nil {
 		return nil, err
 	}
-	defer ds.Close()
 
-	digester := digest.Canonical.Digester()
-	rc := &readCounter{
-		r: io.TeeReader(ds, digester.Hash()),
-	}
+	return &diffapi.ApplyResponse{
+		Applied: fromDescriptor(ocidesc),
+	}, nil
 
-	if _, err := archive.Apply(ctx, dir, rc); err != nil {
-		return nil, err
-	}
-
-	// Read any trailing data
-	if _, err := io.Copy(ioutil.Discard, rc); err != nil {
-		return nil, err
-	}
-
-	resp := &diffapi.ApplyResponse{
-		Applied: &descriptor.Descriptor{
-			MediaType: ocispec.MediaTypeImageLayer,
-			Digest:    digester.Digest(),
-			Size_:     rc.c,
-		},
-	}
-
-	return resp, nil
 }
 
 func (s *service) Diff(ctx context.Context, dr *diffapi.DiffRequest) (*diffapi.DiffResponse, error) {
 	aMounts := toMounts(dr.Left)
 	bMounts := toMounts(dr.Right)
 
-	aDir, err := ioutil.TempDir("", "left-")
+	ocidesc, err := s.diff.DiffMounts(ctx, aMounts, bMounts, dr.MediaType, dr.Ref)
 	if err != nil {
-		return nil, errors.Wrap(err, "failed to create temporary directory")
-	}
-	defer os.RemoveAll(aDir)
-
-	bDir, err := ioutil.TempDir("", "right-")
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to create temporary directory")
-	}
-	defer os.RemoveAll(bDir)
-
-	if err := mount.MountAll(aMounts, aDir); err != nil {
-		return nil, errors.Wrap(err, "failed to mount")
-	}
-	defer mount.Unmount(aDir, 0)
-
-	if err := mount.MountAll(bMounts, bDir); err != nil {
-		return nil, errors.Wrap(err, "failed to mount")
-	}
-	defer mount.Unmount(bDir, 0)
-
-	cw, err := s.store.Writer(ctx, dr.Ref, 0, "")
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to open writer")
-	}
-
-	// TODO: Validate media type
-
-	// TODO: Support compressed media types (link compressed to uncompressed)
-	//dgstr := digest.SHA256.Digester()
-	//wc := &writeCounter{}
-	//compressed, err := compression.CompressStream(cw, compression.Gzip)
-	//if err != nil {
-	//	return nil, errors.Wrap(err, "failed to get compressed stream")
-	//}
-	//err = archive.WriteDiff(ctx, io.MultiWriter(compressed, dgstr.Hash(), wc), lowerDir, upperDir)
-	//compressed.Close()
-
-	err = archive.WriteDiff(ctx, cw, aDir, bDir)
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to write diff")
-	}
-
-	dgst := cw.Digest()
-	if err := cw.Commit(0, dgst); err != nil {
-		return nil, errors.Wrap(err, "failed to commit")
-	}
-
-	info, err := s.store.Info(ctx, dgst)
-	if err != nil {
-		return nil, errors.Wrap(err, "failed to get info from content store")
-	}
-
-	desc := ocispec.Descriptor{
-		MediaType: dr.MediaType,
-		Digest:    info.Digest,
-		Size:      info.Size,
+		return nil, err
 	}
 
 	return &diffapi.DiffResponse{
-		Diff: fromDescriptor(desc),
+		Diff: fromDescriptor(ocidesc),
 	}, nil
 }
 
-type readCounter struct {
-	r io.Reader
-	c int64
-}
-
-func (rc *readCounter) Read(p []byte) (n int, err error) {
-	n, err = rc.r.Read(p)
-	rc.c += int64(n)
-	return
-}
-
-func toDescriptor(d *descriptor.Descriptor) ocispec.Descriptor {
-	return ocispec.Descriptor{
-		MediaType: d.MediaType,
-		Digest:    d.Digest,
-		Size:      d.Size_,
-	}
-}
-
 func toMounts(apim []*mounttypes.Mount) []mount.Mount {
 	mounts := make([]mount.Mount, len(apim))
 	for i, m := range apim {