Support copying image indexes

Fixes #23

Makefile

@@ -13,9 +13,10 @@ check-counterfeiter:
 	@which counterfeiter > /dev/null || (echo counterfeiter not found: issue "GO111MODULE=off go get -u github.com/maxbrunsfeld/counterfeiter" && false)
 
 gen-mocks: check-counterfeiter
-	counterfeiter -o pkg/registry/imagefakes/fake_image.go github.com/google/go-containerregistry/pkg/v1.Image
-	counterfeiter -o pkg/registry/imagefakes/fake_image_index.go github.com/google/go-containerregistry/pkg/v1.ImageIndex
+	counterfeiter -o pkg/registry/ggcrfakes/fake_image.go github.com/google/go-containerregistry/pkg/v1.Image
+	counterfeiter -o pkg/registry/ggcrfakes/fake_image_index.go github.com/google/go-containerregistry/pkg/v1.ImageIndex
 	counterfeiter pkg/registry LayoutPath
+	counterfeiter pkg/registry Image
 
 irel: $(GO_SOURCES)
 	GO111MODULE=on go build -o $(OUTPUT) cmd/irel/main.go

pkg/image/digest.go

@@ -18,7 +18,7 @@ package image
 
 import "github.com/opencontainers/go-digest"
 
-// Digest provides a CAS address of an image.
+// Digest provides a CAS address of an image (either an image manifest or a manifest list).
 type Digest struct {
 	dig digest.Digest
 }

pkg/image/name.go

@@ -29,7 +29,7 @@ const (
 	fullDockerHubHost = "index.docker.io"
 )
 
-// Name is a named image reference
+// Name is a named image reference. It can refer to an image manifest or a manifest list (e.g. a multi-arch image).
 type Name struct {
 	ref reference.Named
 }

pkg/irel/copy.go

@@ -19,7 +19,7 @@ package irel
 import (
 	"fmt"
 	"github.com/pivotal/image-relocation/pkg/image"
-	"github.com/pivotal/image-relocation/pkg/registry"
+	"github.com/pivotal/image-relocation/pkg/registry/ggcr"
 	"github.com/spf13/cobra"
 	"log"
 )
@@ -47,7 +47,7 @@ func copy(cmd *cobra.Command, args []string) {
 		log.Fatalf("invalid reference %q: %v", dstStr, err)
 	}
 
-	regClient := registry.NewRegistryClient()
+	regClient := ggcr.NewRegistryClient()
 	dig, _, err := regClient.Copy(src, dst)
 	if err != nil {
 		log.Fatalf("copy failed: %v", err)

pkg/irel/digest.go

@@ -19,7 +19,7 @@ package irel
 import (
 	"fmt"
 	"github.com/pivotal/image-relocation/pkg/image"
-	"github.com/pivotal/image-relocation/pkg/registry"
+	"github.com/pivotal/image-relocation/pkg/registry/ggcr"
 	"github.com/spf13/cobra"
 	"log"
 )
@@ -43,7 +43,7 @@ func digest(cmd *cobra.Command, args []string) {
 		log.Fatalf("invalid reference %q: %v", refStr, err)
 	}
 
-	regClient := registry.NewRegistryClient()
+	regClient := ggcr.NewRegistryClient()
 	dig, err := regClient.Digest(ref)
 	if err != nil {
 		log.Fatalf("digest failed: %v", err)

pkg/irel/layout_add.go

@@ -19,7 +19,7 @@ package irel
 import (
 	"fmt"
 	"github.com/pivotal/image-relocation/pkg/image"
-	"github.com/pivotal/image-relocation/pkg/registry"
+	"github.com/pivotal/image-relocation/pkg/registry/ggcr"
 	"github.com/spf13/cobra"
 	"log"
 )
@@ -40,8 +40,8 @@ func layoutAdd(cmd *cobra.Command, args []string) {
 		log.Fatalf("invalid reference %q: %v", refStr, err)
 	}
 
-	regClient := registry.NewRegistryClient()
-	layout, err := regClient.ReadLayout(layoutPath)
+	regClient := ggcr.NewRegistryClient()
+	layout, err := regClient.NewLayout(layoutPath)
 	if err != nil {
 		layout, err = regClient.NewLayout(layoutPath)
 		if err != nil {

pkg/irel/layout_find.go

@@ -19,7 +19,7 @@ package irel
 import (
 	"fmt"
 	"github.com/pivotal/image-relocation/pkg/image"
-	"github.com/pivotal/image-relocation/pkg/registry"
+	"github.com/pivotal/image-relocation/pkg/registry/ggcr"
 	"github.com/spf13/cobra"
 	"log"
 )
@@ -40,7 +40,7 @@ func layoutFind(cmd *cobra.Command, args []string) {
 		log.Fatalf("invalid reference %q: %v", refStr, err)
 	}
 
-	regClient := registry.NewRegistryClient()
+	regClient := ggcr.NewRegistryClient()
 	layout, err := regClient.ReadLayout(layoutPath)
 	if err != nil {
 		log.Fatalf("failed to create OCI image layout: %v", err)

pkg/irel/layout_push.go

@@ -19,7 +19,7 @@ package irel
 import (
 	"fmt"
 	"github.com/pivotal/image-relocation/pkg/image"
-	"github.com/pivotal/image-relocation/pkg/registry"
+	"github.com/pivotal/image-relocation/pkg/registry/ggcr"
 	"github.com/spf13/cobra"
 	"log"
 )
@@ -45,7 +45,7 @@ func layoutPush(cmd *cobra.Command, args []string) {
 		log.Fatalf("invalid digest %q: %v", digStr, err)
 	}
 
-	regClient := registry.NewRegistryClient()
+	regClient := ggcr.NewRegistryClient()
 	layout, err := regClient.ReadLayout(layoutPath)
 	if err != nil {
 		log.Fatalf("failed to access OCI image layout: %v", err)

pkg/registry/client.go

@@ -17,9 +17,6 @@
 package registry
 
 import (
-	"fmt"
-
-	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/pivotal/image-relocation/pkg/image"
 )
 
@@ -41,58 +38,3 @@ type Client interface {
 	ReadLayout(path string) (Layout, error)
 }
 
-type client struct {
-	readRemoteImage  func(n image.Name) (v1.Image, error)
-	writeRemoteImage func(i v1.Image, n image.Name) error
-}
-
-// NewRegistryClient returns a new Client.
-func NewRegistryClient() Client {
-	return &client{
-		readRemoteImage:  readRemoteImage,
-		writeRemoteImage: writeRemoteImage,
-	}
-}
-
-func (r *client) Digest(n image.Name) (image.Digest, error) {
-	img, err := r.readRemoteImage(n)
-	if err != nil {
-		return image.EmptyDigest, err
-	}
-
-	hash, err := img.Digest()
-	if err != nil {
-		return image.EmptyDigest, err
-	}
-
-	return image.NewDigest(hash.String())
-}
-
-func (r *client) Copy(source image.Name, target image.Name) (image.Digest, int64, error) {
-	img, err := r.readRemoteImage(source)
-	if err != nil {
-		return image.EmptyDigest, 0, fmt.Errorf("failed to read image %v: %v", source, err)
-	}
-
-	hash, err := img.Digest()
-	if err != nil {
-		return image.EmptyDigest, 0, fmt.Errorf("failed to read digest of image %v: %v", source, err)
-	}
-
-	err = r.writeRemoteImage(img, target)
-	if err != nil {
-		return image.EmptyDigest, 0, fmt.Errorf("failed to write image %v: %v", target, err)
-	}
-
-	dig, err := image.NewDigest(hash.String())
-	if err != nil {
-		return image.EmptyDigest, 0, err
-	}
-
-	rawManifest, err := img.RawManifest()
-	if err != nil {
-		return image.EmptyDigest, 0, fmt.Errorf("failed to get raw manifest of image %v: %v", source, err)
-	}
-
-	return dig, int64(len(rawManifest)), nil
-}

pkg/registry/ggcr/client.go

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2019-Present Pivotal Software, Inc. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package ggcr
+
+import (
+	"fmt"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/pivotal/image-relocation/pkg/image"
+	"github.com/pivotal/image-relocation/pkg/registry"
+)
+
+type manifestWriter func(i v1.Image, n image.Name) error
+type indexWriter func(i v1.ImageIndex, n image.Name) error
+
+type client struct {
+	readRemoteImage  func(n image.Name) (registry.Image, error)
+	writeRemoteImage manifestWriter
+	writeRemoteIndex indexWriter
+}
+
+// NewRegistryClient returns a new Client.
+func NewRegistryClient() registry.Client {
+	return &client{
+		readRemoteImage:  readRemoteImage(writeRemoteImage, writeRemoteIndex),
+		writeRemoteImage: writeRemoteImage,
+		writeRemoteIndex: writeRemoteIndex,
+	}
+}
+
+func (r *client) Digest(n image.Name) (image.Digest, error) {
+	img, err := r.readRemoteImage(n)
+	if err != nil {
+		return image.EmptyDigest, err
+	}
+
+	hash, err := img.Digest()
+	if err != nil {
+		return image.EmptyDigest, err
+	}
+
+	return image.NewDigest(hash.String())
+}
+
+func (r *client) Copy(source image.Name, target image.Name) (image.Digest, int64, error) {
+	img, err := r.readRemoteImage(source)
+	if err != nil {
+		return image.EmptyDigest, 0, fmt.Errorf("failed to read image %v: %v", source, err)
+	}
+
+	sourceDigest, err := img.Digest()
+	if err != nil {
+		return image.EmptyDigest, 0, fmt.Errorf("failed to read digest of image %v: %v", source, err)
+	}
+
+	targetDigest, s, err := img.Write(target)
+	if err != nil {
+		return image.EmptyDigest, 0 , fmt.Errorf("failed to write image %v: %v", target, err)
+	}
+	if sourceDigest != targetDigest {
+		return image.EmptyDigest, 0, fmt.Errorf("failed to preserve digest of image %v: source digest %v, target digest %v", source, sourceDigest, targetDigest)
+	}
+	return targetDigest, s, err
+}