Introduce --index and --oci options

This let user tune the media type to be used to get manifest, without breaking compatibility.

Signed-off-by: Nicolas De Loof <[email protected]>

Author: ndeloof

README.md

@@ -139,6 +139,12 @@ $ reg manifest r.j3ss.co/htop
  }
 ```
 
+For multi-architecture docker images, `--index` allow to get the Manifest index (a.k.a Manifest List) with
+all supported platforms/architecture listed.
+
+OCI compatibility can be checked using `--oci` option, which will force use of [OCI media types](https://github.com/opencontainers/image-spec/blob/master/media-types.md).
+
+
 ### Get the Digest
 ```console
 $ reg digest r.j3ss.co/htop

digest.go

@@ -16,9 +16,15 @@ func (cmd *digestCommand) ShortHelp() string { return digestHelp }
 func (cmd *digestCommand) LongHelp() string  { return digestHelp }
 func (cmd *digestCommand) Hidden() bool      { return false }
 
-func (cmd *digestCommand) Register(fs *flag.FlagSet) {}
+func (cmd *digestCommand) Register(fs *flag.FlagSet) {
+	fs.BoolVar(&cmd.index, "index", false, "get manifest index (multi-architecture images, docker apps)")
+	fs.BoolVar(&cmd.oci, "oci", false, "use OCI media type only")
+}
 
-type digestCommand struct{}
+type digestCommand struct {
+	index bool
+	oci   bool
+}
 
 func (cmd *digestCommand) Run(ctx context.Context, args []string) error {
 	if len(args) < 1 {
@@ -37,7 +43,7 @@ func (cmd *digestCommand) Run(ctx context.Context, args []string) error {
 	}
 
 	// Get the digest.
-	digest, err := r.Digest(ctx, image)
+	digest, err := r.Digest(ctx, image, mediatypes(cmd.index, cmd.oci)...)
 	if err != nil {
 		return err
 	}

manifest.go

@@ -5,8 +5,10 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
-
+	"github.com/docker/distribution/manifest/manifestlist"
+	"github.com/docker/distribution/manifest/schema2"
 	"github.com/genuinetools/reg/registry"
+	v1 "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 const manifestHelp = `Get the json manifest for a repository.`
@@ -19,10 +21,14 @@ func (cmd *manifestCommand) Hidden() bool      { return false }
 
 func (cmd *manifestCommand) Register(fs *flag.FlagSet) {
 	fs.BoolVar(&cmd.v1, "v1", false, "force the version of the manifest retrieved to v1")
+	fs.BoolVar(&cmd.index, "index", false, "get manifest index (multi-architecture images, docker apps)")
+	fs.BoolVar(&cmd.oci, "oci", false, "use OCI media type only")
 }
 
 type manifestCommand struct {
-	v1 bool
+	v1    bool
+	index bool
+	oci   bool
 }
 
 func (cmd *manifestCommand) Run(ctx context.Context, args []string) error {
@@ -50,7 +56,7 @@ func (cmd *manifestCommand) Run(ctx context.Context, args []string) error {
 		}
 	} else {
 		// Get the v2 manifest.
-		manifest, err = r.Manifest(ctx, image.Path, image.Reference())
+		manifest, err = r.Manifest(ctx, image.Path, image.Reference(), mediatypes(cmd.index, cmd.oci)...)
 		if err != nil {
 			return err
 		}
@@ -64,3 +70,20 @@ func (cmd *manifestCommand) Run(ctx context.Context, args []string) error {
 	fmt.Println(string(b))
 	return nil
 }
+
+func mediatypes(index, oci bool) []string {
+	mediatypes := []string{}
+	if oci {
+		mediatypes = append(mediatypes, v1.MediaTypeImageManifest)
+	} else {
+		mediatypes = append(mediatypes, schema2.MediaTypeManifest)
+	}
+	if index {
+		if oci {
+			mediatypes = append(mediatypes, v1.MediaTypeImageIndex)
+		} else {
+			mediatypes = append(mediatypes, manifestlist.MediaTypeManifestList)
+		}
+	}
+	return mediatypes
+}

manifest_test.go

@@ -31,12 +31,12 @@ func TestManifestV1(t *testing.T) {
 }
 
 func TestManifestList(t *testing.T) {
-	out, err := run("manifest", "docker.io/ndeloof/hello-app")
+	out, err := run("manifest", "--index", "docker.io/library/busybox")
 	if err != nil {
 		t.Fatalf("output: %s, error: %v", out, err)
 	}
 
-	expected := `"schemaVersion": 2,`
+	expected := `"mediaType": "application\/vnd.docker.distribution.manifest.list.v2+json"`
 	if !strings.Contains(out, expected) {
 		t.Fatalf("expected: %s\ngot: %s", expected, out)
 	}

registry/digest.go

@@ -3,14 +3,16 @@ package registry
 import (
 	"context"
 	"fmt"
+	"github.com/docker/distribution/manifest/schema2"
+	"github.com/sirupsen/logrus"
 	"net/http"
+	"strings"
 
-	"github.com/docker/distribution/manifest/schema2"
-	digest "github.com/opencontainers/go-digest"
+	"github.com/opencontainers/go-digest"
 )
 
 // Digest returns the digest for an image.
-func (r *Registry) Digest(ctx context.Context, image Image) (digest.Digest, error) {
+func (r *Registry) Digest(ctx context.Context, image Image, mediatypes ...string) (digest.Digest, error) {
 	if len(image.Digest) > 1 {
 		// return early if we already have an image digest.
 		return image.Digest, nil
@@ -25,7 +27,12 @@ func (r *Registry) Digest(ctx context.Context, image Image) (digest.Digest, erro
 		return "", err
 	}
 
-	req.Header.Add("Accept", schema2.MediaTypeManifest)
+	if mediatypes == nil {
+		mediatypes = []string{schema2.MediaTypeManifest}
+	}
+	logrus.Debugf("Using media types %s", mediatypes)
+	req.Header.Add("Accept", strings.Join(mediatypes, ", "))
+
 	resp, err := r.Client.Do(req.WithContext(ctx))
 	if err != nil {
 		return "", err

registry/manifest.go

@@ -5,8 +5,10 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"github.com/sirupsen/logrus"
 	"io/ioutil"
 	"net/http"
+	"strings"
 
 	"github.com/docker/distribution"
 	"github.com/docker/distribution/manifest/manifestlist"
@@ -20,7 +22,7 @@ var (
 )
 
 // Manifest returns the manifest for a specific repository:tag.
-func (r *Registry) Manifest(ctx context.Context, repository, ref string) (distribution.Manifest, error) {
+func (r *Registry) Manifest(ctx context.Context, repository, ref string, mediatypes ...string) (distribution.Manifest, error) {
 	uri := r.url("/v2/%s/manifests/%s", repository, ref)
 	r.Logf("registry.manifests uri=%s repository=%s ref=%s", uri, repository, ref)
 
@@ -29,7 +31,11 @@ func (r *Registry) Manifest(ctx context.Context, repository, ref string) (distri
 		return nil, err
 	}
 
-	req.Header.Add("Accept", schema2.MediaTypeManifest+", "+manifestlist.MediaTypeManifestList)
+	if mediatypes == nil {
+		mediatypes = []string{schema2.MediaTypeManifest}
+	}
+	logrus.Debugf("Using media types %s", mediatypes)
+	req.Header.Add("Accept", strings.Join(mediatypes, ", "))
 
 	resp, err := r.Client.Do(req.WithContext(ctx))
 	if err != nil {