Add manifest type conversion to buildah push

buildah push supports manifest type conversion when pushing using the 'dir' transport
Manifest types include oci, v2s1, and v2s2
e.g buildah push --format v2s2 alpine dir:my-directory

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

Closes: #321
Approved by: rhatdan

cmd/buildah/push.go

@@ -5,9 +5,11 @@ import (
 	"os"
 	"strings"
 
+	"github.com/containers/image/manifest"
 	"github.com/containers/image/transports"
 	"github.com/containers/image/transports/alltransports"
 	"github.com/containers/storage/pkg/archive"
+	imgspecv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/pkg/errors"
 	"github.com/projectatomic/buildah"
 	"github.com/urfave/cli"
@@ -29,6 +31,10 @@ var (
 			Name:  "disable-compression, D",
 			Usage: "don't compress layers",
 		},
+		cli.StringFlag{
+			Name:  "format, f",
+			Usage: "manifest type (oci, v2s1, or v2s2) to use when saving image using the 'dir:' transport (default is manifest type of source)",
+		},
 		cli.BoolFlag{
 			Name:  "quiet, q",
 			Usage: "don't output progress information when pushing images",
@@ -104,8 +110,23 @@ func pushCmd(c *cli.Context) error {
 		return errors.Wrapf(err, "error building system context")
 	}
 
+	var manifestType string
+	if c.IsSet("format") {
+		switch c.String("format") {
+		case "oci":
+			manifestType = imgspecv1.MediaTypeImageManifest
+		case "v2s1":
+			manifestType = manifest.DockerV2Schema1SignedMediaType
+		case "v2s2", "docker":
+			manifestType = manifest.DockerV2Schema2MediaType
+		default:
+			return fmt.Errorf("unknown format %q. Choose on of the supported formats: 'oci', 'v2s1', or 'v2s2'", c.String("format"))
+		}
+	}
+
 	options := buildah.PushOptions{
 		Compression:         compress,
+		ManifestType:        manifestType,
 		SignaturePolicyPath: c.String("signature-policy"),
 		Store:               store,
 		SystemContext:       systemContext,

commit.go

@@ -80,6 +80,9 @@ type PushOptions struct {
 	// github.com/containers/image/types SystemContext to hold credentials
 	// and other authentication/authorization information.
 	SystemContext *types.SystemContext
+	// ManifestType is the format to use when saving the imge using the 'dir' transport
+	// possible options are oci, v2s1, and v2s2
+	ManifestType string
 }
 
 // shallowCopy copies the most recent layer, the configuration, and the manifest from one image to another.
@@ -256,7 +259,7 @@ func (b *Builder) Commit(dest types.ImageReference, options CommitOptions) error
 	}
 	if exporting {
 		// Copy everything.
-		err = cp.Image(policyContext, dest, src, getCopyOptions(options.ReportWriter, nil, options.SystemContext))
+		err = cp.Image(policyContext, dest, src, getCopyOptions(options.ReportWriter, nil, options.SystemContext, ""))
 		if err != nil {
 			return errors.Wrapf(err, "error copying layers and metadata")
 		}
@@ -328,7 +331,7 @@ func Push(image string, dest types.ImageReference, options PushOptions) error {
 		return errors.Wrapf(err, "error recomputing layer digests and building metadata")
 	}
 	// Copy everything.
-	err = cp.Image(policyContext, dest, src, getCopyOptions(options.ReportWriter, nil, options.SystemContext))
+	err = cp.Image(policyContext, dest, src, getCopyOptions(options.ReportWriter, nil, options.SystemContext, options.ManifestType))
 	if err != nil {
 		return errors.Wrapf(err, "error copying layers and metadata")
 	}

common.go

@@ -7,11 +7,12 @@ import (
 	"github.com/containers/image/types"
 )
 
-func getCopyOptions(reportWriter io.Writer, sourceSystemContext *types.SystemContext, destinationSystemContext *types.SystemContext) *cp.Options {
+func getCopyOptions(reportWriter io.Writer, sourceSystemContext *types.SystemContext, destinationSystemContext *types.SystemContext, manifestType string) *cp.Options {
 	return &cp.Options{
-		ReportWriter:   reportWriter,
-		SourceCtx:      sourceSystemContext,
-		DestinationCtx: destinationSystemContext,
+		ReportWriter:          reportWriter,
+		SourceCtx:             sourceSystemContext,
+		DestinationCtx:        destinationSystemContext,
+		ForceManifestMIMEType: manifestType,
 	}
 }
 

contrib/completions/bash/buildah

@@ -483,6 +483,8 @@ return 1
      local options_with_args="
           --cert-dir
           --creds
+          --format
+          -f
           --signature-policy
   "
 

docs/buildah-push.md

@@ -52,6 +52,10 @@ The username[:password] to use to authenticate with the registry if required.
 
 Don't compress copies of filesystem layers which will be pushed.
 
+**--format, -f**
+
+Manifest Type (oci, v2s1, or v2s2) to use when saving image to directory using the 'dir:' transport (default is manifest type of source)
+
 **--quiet**
 
 When writing the output image, suppress progress output.

pull.go

@@ -109,6 +109,6 @@ func pullImage(store storage.Store, options BuilderOptions, sc *types.SystemCont
 
 	logrus.Debugf("copying %q to %q", spec, name)
 
-	err = cp.Image(policyContext, destRef, srcRef, getCopyOptions(options.ReportWriter, options.SystemContext, nil))
+	err = cp.Image(policyContext, destRef, srcRef, getCopyOptions(options.ReportWriter, options.SystemContext, nil, ""))
 	return destRef, err
 }

tests/push.bats

@@ -18,3 +18,23 @@ load helpers
     buildah rm "$cid"
   done
 }
+
+@test "push with manifest type conversion" {
+  cid=$(buildah from --pull --signature-policy ${TESTSDIR}/policy.json alpine)
+  run buildah push --signature-policy ${TESTSDIR}/policy.json --format oci alpine dir:my-dir
+  echo "$output"
+  [ "$status" -eq 0 ]
+  manifest=$(cat my-dir/manifest.json)
+  run grep "application/vnd.oci.image.config.v1+json" <<< "$manifest"
+  echo "$output"
+  [ "$status" -eq 0 ]
+  run buildah push --signature-policy ${TESTSDIR}/policy.json --format v2s2 alpine dir:my-dir
+  echo "$output"
+  [ "$status" -eq 0 ]
+  run grep "application/vnd.docker.distribution.manifest.v2+json" my-dir/manifest.json
+  echo "$output"
+  [ "$status" -eq 0 ]
+  buildah rm "$cid"
+  buildah rmi alpine
+  rm -rf my-dir
+}

vendor.conf

@@ -1,7 +1,7 @@
 github.com/BurntSushi/toml master
 github.com/Nvveen/Gotty master
 github.com/blang/semver master
-github.com/containers/image 063852766c3e82ec8359ce5f6612e056f3efaa76
+github.com/containers/image f950aa3529148eb0dea90888c24b6682da641b13
 github.com/containers/storage d7921c6facc516358070a1306689eda18adaa20a
 github.com/docker/distribution 5f6282db7d65e6d72ad7c2cc66310724a57be716
 github.com/docker/docker 30eb4d8cdc422b023d5f11f29a82ecb73554183b