Add manifest type conversion to skopeo with dir transport

User can select from 3 manifest types: oci, v2s1, or v2s2
skopeo copy defaults to oci manifest if the --format flag is not set
Adds option to compress blobs when saving to the directory using the dir transport
e.g skopeo copy --format v2s1 --compress-blobs docker-archive:alp.tar dir:my-directory

Signed-off-by: Urvashi Mohnani <umohnani@redhat.com>

cmd/skopeo/copy.go

@@ -7,9 +7,11 @@ import (
 	"strings"
 
 	"github.com/containers/image/copy"
+	"github.com/containers/image/manifest"
 	"github.com/containers/image/transports"
 	"github.com/containers/image/transports/alltransports"
 	"github.com/containers/image/types"
+	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/urfave/cli"
 )
 
@@ -55,12 +57,27 @@ func copyHandler(context *cli.Context) error {
 		return err
 	}
 
+	var manifestType string
+	if context.IsSet("format") {
+		switch context.String("format") {
+		case "oci":
+			manifestType = imgspecv1.MediaTypeImageManifest
+		case "v2s1":
+			manifestType = manifest.DockerV2Schema1SignedMediaType
+		case "v2s2":
+			manifestType = manifest.DockerV2Schema2MediaType
+		default:
+			return fmt.Errorf("unknown format %q. Choose on of the supported formats: 'oci', 'v2s1', or 'v2s2'", context.String("format"))
+		}
+	}
+
 	return copy.Image(policyContext, destRef, srcRef, &copy.Options{
 		RemoveSignatures:      removeSignatures,
 		SignBy:                signBy,
 		ReportWriter:          os.Stdout,
 		SourceCtx:             sourceCtx,
 		DestinationCtx:        destinationCtx,
+		ForceManifestMIMEType: manifestType,
 	})
 }
 
@@ -131,5 +148,13 @@ var copyCmd = cli.Command{
 			Value: "",
 			Usage: "`DIRECTORY` to use to store retrieved blobs (OCI layout destinations only)",
 		},
+		cli.StringFlag{
+			Name:  "format, f",
+			Usage: "`MANIFEST TYPE` (oci, v2s1, or v2s2) to use when saving image to directory using the 'dir:' transport (default is manifest type of source)",
+		},
+		cli.BoolFlag{
+			Name:  "dest-compress",
+			Usage: "Compress tarball image layers when saving to directory using the 'dir' transport. (default is same compression type as source)",
+		},
 	},
 }

cmd/skopeo/utils.go

@@ -18,6 +18,7 @@ func contextFromGlobalOptions(c *cli.Context, flagPrefix string) (*types.SystemC
 		DockerInsecureSkipTLSVerify: !c.GlobalBoolT("tls-verify"),
 		OSTreeTmpDirPath:            c.String(flagPrefix + "ostree-tmp-dir"),
 		OCISharedBlobDirPath:        c.String(flagPrefix + "shared-blob-dir"),
+		DirForceCompress:            c.Bool(flagPrefix + "compress"),
 	}
 	if c.IsSet(flagPrefix + "tls-verify") {
 		ctx.DockerInsecureSkipTLSVerify = !c.BoolT(flagPrefix + "tls-verify")

completions/bash/skopeo

@@ -21,6 +21,7 @@ _complete_() {
 
 _skopeo_copy() {
     local options_with_args="
+    --format -f
     --sign-by
     --src-creds --screds
     --src-cert-dir
@@ -30,9 +31,12 @@ _skopeo_copy() {
     --dest-ostree-tmp-dir
     --dest-tls-verify
     "
+
     local boolean_options="
+    --dest-compress
     --remove-signatures
     "
+
     _complete_ "$options_with_args" "$boolean_options"
 }
 

docs/skopeo.1.md

@@ -60,12 +60,16 @@ Uses the system's trust policy to validate images, rejects images not trusted by
 
   _destination-image_ use the "image name" format described above
 
+  **--format, -f** _manifest-type_ Manifest type (oci, v2s1, or v2s2) to use when saving image to directory using the 'dir:' transport (default is manifest type of source)
+
   **--remove-signatures** do not copy signatures, if any, from _source-image_. Necessary when copying a signed image to a destination which does not support signatures.
 
   **--sign-by=**_key-id_ add a signature using that key ID for an image name corresponding to _destination-image_
 
   **--src-creds** _username[:password]_ for accessing the source registry
 
+  **--dest-compress** _bool-value_ Compress tarball image layers when saving to directory using the 'dir' transport. (default is same compression type as source)
+
   **--dest-creds** _username[:password]_ for accessing the destination registry
 
   **--src-cert-dir** _path_ Use certificates at _path_ (*.crt, *.cert, *.key) to connect to the source registry

integration/copy_test.go

@@ -15,6 +15,7 @@ import (
 	"github.com/containers/image/signature"
 	"github.com/go-check/check"
 	"github.com/opencontainers/go-digest"
+	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/opencontainers/image-tools/image"
 )
 
@@ -591,6 +592,32 @@ func (s *CopySuite) TestCopySchemaConversion(c *check.C) {
 	s.testCopySchemaConversionRegistries(c, "docker://"+v2s1DockerRegistryURL+"/schema1", "docker://"+v2DockerRegistryURL+"/schema2")
 }
 
+func (s *CopySuite) TestCopyManifestConversion(c *check.C) {
+	topDir, err := ioutil.TempDir("", "manifest-conversion")
+	c.Assert(err, check.IsNil)
+	defer os.RemoveAll(topDir)
+	srcDir := filepath.Join(topDir, "source")
+	destDir1 := filepath.Join(topDir, "dest1")
+	destDir2 := filepath.Join(topDir, "dest2")
+
+	// oci to v2s1 and vice-versa not supported yet
+	// get v2s2 manifest type
+	assertSkopeoSucceeds(c, "", "copy", "docker://busybox", "dir:"+srcDir)
+	verifyManifestMIMEType(c, srcDir, manifest.DockerV2Schema2MediaType)
+	// convert from v2s2 to oci
+	assertSkopeoSucceeds(c, "", "copy", "--format=oci", "dir:"+srcDir, "dir:"+destDir1)
+	verifyManifestMIMEType(c, destDir1, imgspecv1.MediaTypeImageManifest)
+	// convert from oci to v2s2
+	assertSkopeoSucceeds(c, "", "copy", "--format=v2s2", "dir:"+destDir1, "dir:"+destDir2)
+	verifyManifestMIMEType(c, destDir2, manifest.DockerV2Schema2MediaType)
+	// convert from v2s2 to v2s1
+	assertSkopeoSucceeds(c, "", "copy", "--format=v2s1", "dir:"+srcDir, "dir:"+destDir1)
+	verifyManifestMIMEType(c, destDir1, manifest.DockerV2Schema1SignedMediaType)
+	// convert from v2s1 to v2s2
+	assertSkopeoSucceeds(c, "", "copy", "--format=v2s2", "dir:"+destDir1, "dir:"+destDir2)
+	verifyManifestMIMEType(c, destDir2, manifest.DockerV2Schema2MediaType)
+}
+
 func (s *CopySuite) testCopySchemaConversionRegistries(c *check.C, schema1Registry, schema2Registry string) {
 	topDir, err := ioutil.TempDir("", "schema-conversion")
 	c.Assert(err, check.IsNil)

vendor.conf

@@ -1,5 +1,5 @@
 github.com/urfave/cli v1.17.0
-github.com/containers/image master
+github.com/containers/image f950aa3529148eb0dea90888c24b6682da641b13
 github.com/opencontainers/go-digest master
 gopkg.in/cheggaaa/pb.v1 ad4efe000aa550bb54918c06ebbadc0ff17687b9 https://github.com/cheggaaa/pb
 github.com/containers/storage master