Add configuration options to local transfer service

Signed-off-by: Tony Fang <nhfang@amazon.com>

cmd/ctr/commands/images/import.go

@@ -22,6 +22,9 @@ import (
 	"os"
 	"time"
 
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/urfave/cli"
+
 	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/cmd/ctr/commands"
 	"github.com/containerd/containerd/images/archive"
@@ -30,7 +33,6 @@ import (
 	tarchive "github.com/containerd/containerd/pkg/transfer/archive"
 	"github.com/containerd/containerd/pkg/transfer/image"
 	"github.com/containerd/containerd/platforms"
-	"github.com/urfave/cli"
 )
 
 var importCommand = cli.Command{
@@ -127,9 +129,34 @@ If foobar.tar contains an OCI ref named "latest" and anonymous ref "sha256:deadb
 				opts = append(opts, image.WithNamedPrefix(prefix, overwrite))
 			}
 
-			// TODO: Add platform options
+			var platSpec ocispec.Platform
+			//Only when all-platforms not specified, we will check platform value
+			//Implicitly if the platforms is empty, it means all-platforms
+			if !context.Bool("all-platforms") {
+				//If platform specified, use that one, if not use default
+				if platform := context.String("platform"); platform != "" {
+					platSpec, err = platforms.Parse(platform)
+					if err != nil {
+						return err
+					}
+				} else {
+					platSpec = platforms.DefaultSpec()
+				}
+				opts = append(opts, image.WithPlatforms(platSpec))
+			}
 
-			// TODO: Add unpack options
+			if !context.Bool("no-unpack") {
+				snapshotter := context.String("snapshotter")
+				//If OS field is not empty, it means platSpec was updated in the above block
+				//i.e all-platforms was not specified
+				if platSpec.OS != "" {
+					opts = append(opts, image.WithUnpack(platSpec, snapshotter))
+				} else {
+					//empty spec means all platforms
+					var emptySpec ocispec.Platform
+					opts = append(opts, image.WithUnpack(emptySpec, snapshotter))
+				}
+			}
 
 			is := image.NewStore(context.String("index-name"), opts...)
 

cmd/ctr/commands/images/pull.go

@@ -32,6 +32,7 @@ import (
 	"github.com/containerd/containerd/pkg/progress"
 	"github.com/containerd/containerd/pkg/transfer"
 	"github.com/containerd/containerd/pkg/transfer/image"
+	"github.com/containerd/containerd/pkg/transfer/registry"
 	"github.com/containerd/containerd/platforms"
 	"github.com/opencontainers/image-spec/identity"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
@@ -112,6 +113,11 @@ command. As part of this process, we do the following:
 					p = append(p, platforms.DefaultSpec())
 				}
 				sopts = append(sopts, image.WithPlatforms(p...))
+
+				//set unpack configuration
+				for _, platform := range p {
+					sopts = append(sopts, image.WithUnpack(platform, context.String("snapshotter")))
+				}
 			}
 			// TODO: Support unpack for all platforms..?
 			// Pass in a *?
@@ -125,7 +131,7 @@ command. As part of this process, we do the following:
 				sopts = append(sopts, image.WithAllMetadata)
 			}
 
-			reg := image.NewOCIRegistry(ref, nil, ch)
+			reg := registry.NewOCIRegistry(ref, nil, ch)
 			is := image.NewStore(ref, sopts...)
 
 			pf, done := ProgressHandler(ctx, os.Stdout)

cmd/ctr/commands/images/push.go

@@ -34,6 +34,7 @@ import (
 	"github.com/containerd/containerd/pkg/progress"
 	"github.com/containerd/containerd/pkg/transfer"
 	"github.com/containerd/containerd/pkg/transfer/image"
+	"github.com/containerd/containerd/pkg/transfer/registry"
 	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/containerd/remotes"
 	"github.com/containerd/containerd/remotes/docker"
@@ -103,7 +104,7 @@ var pushCommand = cli.Command{
 			if local == "" {
 				local = ref
 			}
-			reg := image.NewOCIRegistry(ref, nil, ch)
+			reg := registry.NewOCIRegistry(ref, nil, ch)
 			is := image.NewStore(local)
 
 			pf, done := ProgressHandler(ctx, os.Stdout)

cmd/ctr/commands/resolver.go

@@ -32,7 +32,7 @@ import (
 
 	"github.com/containerd/console"
 	"github.com/containerd/containerd/log"
-	"github.com/containerd/containerd/pkg/transfer/image"
+	"github.com/containerd/containerd/pkg/transfer/registry"
 	"github.com/containerd/containerd/remotes"
 	"github.com/containerd/containerd/remotes/docker"
 	"github.com/containerd/containerd/remotes/docker/config"
@@ -218,7 +218,7 @@ type staticCredentials struct {
 }
 
 // NewStaticCredentials gets credentials from passing in cli context
-func NewStaticCredentials(ctx gocontext.Context, clicontext *cli.Context, ref string) (image.CredentialHelper, error) {
+func NewStaticCredentials(ctx gocontext.Context, clicontext *cli.Context, ref string) (registry.CredentialHelper, error) {
 	username := clicontext.String("user")
 	var secret string
 	if i := strings.IndexByte(username, ':'); i > 0 {
@@ -248,12 +248,12 @@ func NewStaticCredentials(ctx gocontext.Context, clicontext *cli.Context, ref st
 	}, nil
 }
 
-func (sc *staticCredentials) GetCredentials(ctx gocontext.Context, ref, host string) (image.Credentials, error) {
+func (sc *staticCredentials) GetCredentials(ctx gocontext.Context, ref, host string) (registry.Credentials, error) {
 	if ref == sc.ref {
-		return image.Credentials{
+		return registry.Credentials{
 			Username: sc.username,
 			Secret:   sc.secret,
 		}, nil
 	}
-	return image.Credentials{}, nil
+	return registry.Credentials{}, nil
 }

pkg/transfer/image/imagestore.go

@@ -27,8 +27,8 @@ import (
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/images/archive"
 	"github.com/containerd/containerd/pkg/streaming"
+	"github.com/containerd/containerd/pkg/transfer"
 	"github.com/containerd/containerd/pkg/transfer/plugins"
-	"github.com/containerd/containerd/pkg/unpack"
 	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/containerd/remotes"
 	"github.com/containerd/typeurl/v2"
@@ -51,7 +51,7 @@ type Store struct {
 	// extraReferences are used to store or lookup multiple references
 	extraReferences []Reference
 
-	unpacks []UnpackConfiguration
+	unpacks []transfer.UnpackConfiguration
 }
 
 // Reference is used to create or find a reference for an image
@@ -84,14 +84,6 @@ type Reference struct {
 	SkipNamedDigest bool
 }
 
-// UnpackConfiguration specifies the platform and snapshotter to use for resolving
-// the unpack Platform, if snapshotter is not specified the platform default will
-// be used.
-type UnpackConfiguration struct {
-	Platform    ocispec.Platform
-	Snapshotter string
-}
-
 // StoreOpt defines options when configuring an image store source or destination
 type StoreOpt func(*Store)
 
@@ -171,7 +163,7 @@ func WithExtraReference(name string) StoreOpt {
 // WithUnpack specifies a platform to unpack for and an optional snapshotter to use
 func WithUnpack(p ocispec.Platform, snapshotter string) StoreOpt {
 	return func(s *Store) {
-		s.unpacks = append(s.unpacks, UnpackConfiguration{
+		s.unpacks = append(s.unpacks, transfer.UnpackConfiguration{
 			Platform:    p,
 			Snapshotter: snapshotter,
 		})
@@ -333,11 +325,11 @@ func (is *Store) Get(ctx context.Context, store images.Store) (images.Image, err
 	return store.Get(ctx, is.imageName)
 }
 
-func (is *Store) UnpackPlatforms() []unpack.Platform {
+func (is *Store) UnpackPlatforms() []transfer.UnpackConfiguration {
-	unpacks := make([]unpack.Platform, len(is.unpacks))
+	unpacks := make([]transfer.UnpackConfiguration, len(is.unpacks))
 	for i, uc := range is.unpacks {
-		unpacks[i].SnapshotterKey = uc.Snapshotter
+		unpacks[i].Snapshotter = uc.Snapshotter
-		unpacks[i].Platform = platforms.Only(uc.Platform)
+		unpacks[i].Platform = uc.Platform
 	}
 	return unpacks
 }
@@ -424,7 +416,7 @@ func referencesFromProto(references []*transfertypes.ImageReference) []Reference
 	}
 	return or
 }
-func unpackToProto(uc []UnpackConfiguration) []*transfertypes.UnpackConfiguration {
+func unpackToProto(uc []transfer.UnpackConfiguration) []*transfertypes.UnpackConfiguration {
 	auc := make([]*transfertypes.UnpackConfiguration, len(uc))
 	for i := range uc {
 		p := types.Platform{
@@ -440,8 +432,8 @@ func unpackToProto(uc []UnpackConfiguration) []*transfertypes.UnpackConfiguratio
 	return auc
 }
 
-func unpackFromProto(auc []*transfertypes.UnpackConfiguration) []UnpackConfiguration {
+func unpackFromProto(auc []*transfertypes.UnpackConfiguration) []transfer.UnpackConfiguration {
-	uc := make([]UnpackConfiguration, len(auc))
+	uc := make([]transfer.UnpackConfiguration, len(auc))
 	for i := range auc {
 		uc[i].Snapshotter = auc[i].Snapshotter
 		if auc[i].Platform != nil {

pkg/transfer/local/import.go

@@ -19,13 +19,16 @@ package local
 import (
 	"context"
 	"encoding/json"
+	"fmt"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/log"
 	"github.com/containerd/containerd/pkg/transfer"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/containerd/containerd/pkg/unpack"
 )
 
 func (ts *localTransferService) importStream(ctx context.Context, i transfer.ImageImporter, is transfer.ImageStorer, tops *transfer.Config) error {
@@ -46,12 +49,16 @@ func (ts *localTransferService) importStream(ctx context.Context, i transfer.Ima
 		return err
 	}
 
-	var descriptors []ocispec.Descriptor
+	var (
+		descriptors []ocispec.Descriptor
+		handler     images.Handler
+		unpacker    *unpack.Unpacker
+	)
 
 	// If save index, add index
 	descriptors = append(descriptors, index)
 
-	var handler images.HandlerFunc = func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
+	var handlerFunc images.HandlerFunc = func(ctx context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
 		// Only save images at top level
 		if desc.Digest != index.Digest {
 			return images.Children(ctx, ts.content, desc)
@@ -76,7 +83,33 @@ func (ts *localTransferService) importStream(ctx context.Context, i transfer.Ima
 	}
 
 	if f, ok := is.(transfer.ImageFilterer); ok {
-		handler = f.ImageFilter(handler, ts.content)
+		handlerFunc = f.ImageFilter(handlerFunc, ts.content)
+	}
+
+	handler = images.Handlers(handlerFunc)
+
+	// First find suitable platforms to unpack into
+	//If image storer is also an unpacker type, i.e implemented UnpackPlatforms() func
+	if iu, ok := is.(transfer.ImageUnpacker); ok {
+		unpacks := iu.UnpackPlatforms()
+		if len(unpacks) > 0 {
+			uopts := []unpack.UnpackerOpt{}
+			for _, u := range unpacks {
+				matched, mu := getSupportedPlatform(u, ts.config.UnpackPlatforms)
+				if matched {
+					uopts = append(uopts, unpack.WithUnpackPlatform(mu))
+				}
+			}
+
+			if ts.config.DuplicationSuppressor != nil {
+				uopts = append(uopts, unpack.WithDuplicationSuppressor(ts.config.DuplicationSuppressor))
+			}
+			unpacker, err = unpack.NewUnpacker(ctx, ts.content, uopts...)
+			if err != nil {
+				return fmt.Errorf("unable to initialize unpacker: %w", err)
+			}
+			handler = unpacker.Unpack(handler)
+		}
 	}
 
 	if err := images.WalkNotEmpty(ctx, handler, index); err != nil {

pkg/transfer/local/pull.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 
+	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
@@ -73,6 +74,8 @@ func (ts *localTransferService) pull(ctx context.Context, ir transfer.ImageFetch
 	var (
 		handler images.Handler
 
+		baseHandlers []images.Handler
+
 		unpacker *unpack.Unpacker
 
 		// has a config media type bug (distribution#1622)
@@ -97,12 +100,6 @@ func (ts *localTransferService) pull(ctx context.Context, ir transfer.ImageFetch
 		childrenHandler = f.ImageFilter(childrenHandler, store)
 	}
 
-	// Sort and limit manifests if a finite number is needed
-	//if limit > 0 {
-	//	childrenHandler = images.LimitManifests(childrenHandler, rCtx.PlatformMatcher, limit)
-	//}
-	//SetChildrenMappedLabels(manager content.Manager, f HandlerFunc, labelMap func(ocispec.Descriptor) []string) HandlerFunc {
-
 	checkNeedsFix := images.HandlerFunc(
 		func(_ context.Context, desc ocispec.Descriptor) ([]ocispec.Descriptor, error) {
 			// set to true if there is application/octet-stream media type
@@ -119,8 +116,12 @@ func (ts *localTransferService) pull(ctx context.Context, ir transfer.ImageFetch
 		return err
 	}
 
-	// TODO: Allow initialization from configuration
+	//Set up baseHandlers from service configuration if present or create a new one
-	baseHandlers := []images.Handler{}
+	if ts.config.BaseHandlers != nil {
+		baseHandlers = ts.config.BaseHandlers
+	} else {
+		baseHandlers = []images.Handler{}
+	}
 
 	if tops.Progress != nil {
 		baseHandlers = append(baseHandlers, images.HandlerFunc(
@@ -149,22 +150,28 @@ func (ts *localTransferService) pull(ctx context.Context, ir transfer.ImageFetch
 		appendDistSrcLabelHandler,
 	)...)
 
-	// TODO: Should available platforms be a configuration of the service?
 	// First find suitable platforms to unpack into
-	//if unpacker, ok := is.
+	//If image storer is also an unpacker type, i.e implemented UnpackPlatforms() func
 	if iu, ok := is.(transfer.ImageUnpacker); ok {
 		unpacks := iu.UnpackPlatforms()
 		if len(unpacks) > 0 {
 			uopts := []unpack.UnpackerOpt{}
+			//Only unpack if requested unpackconfig matches default/supported unpackconfigs
 			for _, u := range unpacks {
-				uopts = append(uopts, unpack.WithUnpackPlatform(u))
+				matched, mu := getSupportedPlatform(u, ts.config.UnpackPlatforms)
+				if matched {
+					uopts = append(uopts, unpack.WithUnpackPlatform(mu))
 				}
-			if ts.limiter != nil {
-				uopts = append(uopts, unpack.WithLimiter(ts.limiter))
 			}
-			//if uconfig.DuplicationSuppressor != nil {
+
-			//	uopts = append(uopts, unpack.WithDuplicationSuppressor(uconfig.DuplicationSuppressor))
+			if ts.limiterD != nil {
-			//}
+				uopts = append(uopts, unpack.WithLimiter(ts.limiterD))
+			}
+
+			if ts.config.DuplicationSuppressor != nil {
+				uopts = append(uopts, unpack.WithDuplicationSuppressor(ts.config.DuplicationSuppressor))
+			}
+
 			unpacker, err = unpack.NewUnpacker(ctx, ts.content, uopts...)
 			if err != nil {
 				return fmt.Errorf("unable to initialize unpacker: %w", err)
@@ -173,7 +180,7 @@ func (ts *localTransferService) pull(ctx context.Context, ir transfer.ImageFetch
 		}
 	}
 
-	if err := images.Dispatch(ctx, handler, ts.limiter, desc); err != nil {
+	if err := images.Dispatch(ctx, handler, ts.limiterD, desc); err != nil {
 		if unpacker != nil {
 			// wait for unpacker to cleanup
 			unpacker.Wait()
@@ -241,3 +248,23 @@ func fetchHandler(ingester content.Ingester, fetcher remotes.Fetcher, pt *Progre
 		}
 	}
 }
+
+// getSupportedPlatform returns a matched platform comparing input UnpackConfiguration to the supported platform/snapshotter combinations
+// If input platform didn't specify snapshotter, default will be used if there is a match on platform.
+func getSupportedPlatform(uc transfer.UnpackConfiguration, supportedPlatforms []unpack.Platform) (bool, unpack.Platform) {
+	var u unpack.Platform
+	for _, sp := range supportedPlatforms {
+		//If both platform and snapshotter match, return the supportPlatform
+		//If platform matched and SnapshotterKey is empty, we assume client didn't pass SnapshotterKey
+		//use default Snapshotter
+		if sp.Platform.Match(uc.Platform) {
+			//assuming sp.SnapshotterKey is not empty
+			if uc.Snapshotter == sp.SnapshotterKey {
+				return true, sp
+			} else if uc.Snapshotter == "" && sp.SnapshotterKey == containerd.DefaultSnapshotter {
+				return true, sp
+			}
+		}
+	}
+	return false, u
+}

pkg/transfer/local/push.go

@@ -105,8 +105,7 @@ func (ts *localTransferService) push(ctx context.Context, ig transfer.ImageGette
 			wrapper = pushCtx.HandlerWrapper
 		}
 	*/
-
+	if err := remotes.PushContent(ctx, pusher, img.Target, ts.content, ts.limiterU, matcher, wrapper); err != nil {
-	if err := remotes.PushContent(ctx, pusher, img.Target, ts.content, ts.limiter, matcher, wrapper); err != nil {
 		return err
 	}
 	if tops.Progress != nil {

pkg/transfer/local/transfer.go

@@ -22,11 +22,15 @@ import (
 	"io"
 	"time"
 
+	"github.com/containerd/containerd"
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/images"
 	"github.com/containerd/containerd/leases"
+	"github.com/containerd/containerd/pkg/kmutex"
 	"github.com/containerd/containerd/pkg/transfer"
+	"github.com/containerd/containerd/pkg/unpack"
+	"github.com/containerd/containerd/platforms"
 	"github.com/containerd/typeurl/v2"
 	"golang.org/x/sync/semaphore"
 )
@@ -35,25 +39,21 @@ type localTransferService struct {
 	leases  leases.Manager
 	content content.Store
 	images  images.Store
-
+	//limiter for upload
-	// semaphore.NewWeighted(int64(rCtx.MaxConcurrentDownloads))
+	limiterU *semaphore.Weighted
-	limiter *semaphore.Weighted
+	//limiter for download operation
-
+	limiterD *semaphore.Weighted
-	// TODO: Duplication suppressor
+	config   TransferConfig
-
-	// Configuration
-	//  - Max downloads
-	//  - Max uploads
-
-	// Supported platforms
-	//  - Platform -> snapshotter defaults?
 }
 
-func NewTransferService(lm leases.Manager, cs content.Store, is images.Store) transfer.Transferrer {
+func NewTransferService(lm leases.Manager, cs content.Store, is images.Store, tc *TransferConfig) transfer.Transferrer {
 	return &localTransferService{
 		leases:   lm,
 		content:  cs,
 		images:   is,
+		limiterU: semaphore.NewWeighted(int64(tc.MaxConcurrentUploadedLayers)),
+		limiterD: semaphore.NewWeighted(int64(tc.MaxConcurrentDownloads)),
+		config:   *tc,
 	}
 }
 
@@ -150,3 +150,40 @@ func (ts *localTransferService) withLease(ctx context.Context, opts ...leases.Op
 		return ls.Delete(ctx, l)
 	}, nil
 }
+
+type TransferConfig struct {
+	// MaxConcurrentDownloads is the max concurrent content downloads for pull.
+	MaxConcurrentDownloads int `toml:"max_concurrent_downloads"`
+
+	// MaxConcurrentUploadedLayers is the max concurrent uploads for push
+	MaxConcurrentUploadedLayers int `toml:"max_concurrent_uploaded_layers"`
+
+	// DuplicationSuppressor is used to make sure that there is only one
+	// in-flight fetch request or unpack handler for a given descriptor's
+	// digest or chain ID.
+	DuplicationSuppressor kmutex.KeyedLocker
+
+	// BaseHandlers are a set of handlers which get are called on dispatch.
+	// These handlers always get called before any operation specific
+	// handlers.
+	BaseHandlers []images.Handler
+
+	//UnpackPlatforms are used to specify supported combination of platforms and snapshotters
+	UnpackPlatforms []unpack.Platform `toml:"unpack_platforms"`
+
+	// RegistryConfigPath is a path to the root directory containing registry-specific configurations
+	RegistryConfigPath string `toml:"config_path"`
+}
+
+func DefaultConfig() *TransferConfig {
+	return &TransferConfig{
+		MaxConcurrentDownloads:      3,
+		MaxConcurrentUploadedLayers: 3,
+		UnpackPlatforms: []unpack.Platform{
+			{
+				Platform:       platforms.Only(platforms.DefaultSpec()),
+				SnapshotterKey: containerd.DefaultSnapshotter,
+			},
+		},
+	}
+}

pkg/transfer/proxy/transfer.go

@@ -21,6 +21,8 @@ import (
 	"errors"
 	"io"
 
+	"google.golang.org/protobuf/types/known/anypb"
+
 	transferapi "github.com/containerd/containerd/api/services/transfer/v1"
 	transfertypes "github.com/containerd/containerd/api/types/transfer"
 	"github.com/containerd/containerd/log"
@@ -28,7 +30,6 @@ import (
 	"github.com/containerd/containerd/pkg/transfer"
 	tstreaming "github.com/containerd/containerd/pkg/transfer/streaming"
 	"github.com/containerd/typeurl/v2"
-	"google.golang.org/protobuf/types/known/anypb"
 )
 
 type proxyTransferrer struct {
@@ -36,7 +37,7 @@ type proxyTransferrer struct {
 	streamCreator streaming.StreamCreator
 }
 
-// NewTransferrer returns a new transferr which communicates over a GRPC
+// NewTransferrer returns a new transferrer which communicates over a GRPC
 // connection using the containerd transfer API
 func NewTransferrer(client transferapi.TransferClient, sc streaming.StreamCreator) transfer.Transferrer {
 	return &proxyTransferrer{

pkg/transfer/registry/registry.go

@@ -14,7 +14,7 @@
    limitations under the License.
 */
 
-package image
+package registry
 
 import (
 	"context"

pkg/transfer/transfer.go

@@ -20,10 +20,10 @@ import (
 	"context"
 	"io"
 
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+
 	"github.com/containerd/containerd/content"
 	"github.com/containerd/containerd/images"
-	"github.com/containerd/containerd/pkg/unpack"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 type Transferrer interface {
@@ -86,8 +86,15 @@ type ImageExportStreamer interface {
 }
 
 type ImageUnpacker interface {
-	// TODO: consider using unpack options
+	UnpackPlatforms() []UnpackConfiguration
-	UnpackPlatforms() []unpack.Platform
+}
+
+// UnpackConfiguration specifies the platform and snapshotter to use for resolving
+// the unpack Platform, if snapshotter is not specified the platform default will
+// be used.
+type UnpackConfiguration struct {
+	Platform    ocispec.Platform
+	Snapshotter string
 }
 
 type ProgressFunc func(Progress)

plugins/transfer/plugin.go

@@ -27,6 +27,7 @@ import (
 	_ "github.com/containerd/containerd/pkg/transfer/image"
 )
 
+// Register local transfer service plugin
 func init() {
 	plugin.Register(&plugin.Registration{
 		Type: plugin.TransferPlugin,
@@ -35,8 +36,9 @@ func init() {
 			plugin.LeasePlugin,
 			plugin.MetadataPlugin,
 		},
-		Config: &transferConfig{},
+		Config: local.DefaultConfig(),
 		InitFn: func(ic *plugin.InitContext) (interface{}, error) {
+			config := ic.Config.(*local.TransferConfig)
 			m, err := ic.Get(plugin.MetadataPlugin)
 			if err != nil {
 				return nil, err
@@ -47,12 +49,7 @@ func init() {
 				return nil, err
 			}
 
-			return local.NewTransferService(l.(leases.Manager), ms.ContentStore(), metadata.NewImageStore(ms)), nil
+			return local.NewTransferService(l.(leases.Manager), ms.ContentStore(), metadata.NewImageStore(ms), config), nil
 		},
 	})
 }
-
-type transferConfig struct {
-	// Max concurrent downloads
-	// Snapshotter platforms
-}

remotes/resolver.go

@@ -34,7 +34,7 @@ type Resolver interface {
 	// reference a specific host or be matched against a specific handler.
 	//
 	// The returned name should be used to identify the referenced entity.
-	// Dependending on the remote namespace, this may be immutable or mutable.
+	// Depending on the remote namespace, this may be immutable or mutable.
 	// While the name may differ from ref, it should itself be a valid ref.
 	//
 	// If the resolution fails, an error will be returned.