fix: oras push should return error when artifacttype is empty for spec 1.1

cmd/oras/internal/option/spec.go

@@ -27,6 +27,7 @@ import (
 const (
 	ImageSpecV1_1 = "v1.1"
 	ImageSpecV1_0 = "v1.0"
+	ImageSpecAuto = "auto"
 )
 
 const (
@@ -36,15 +37,15 @@ const (
 
 // ImageSpec option struct which implements pflag.Value interface.
 type ImageSpec struct {
-	flag        string
+	Flag        string
 	PackVersion oras.PackManifestVersion
 }
 
 // Set validates and sets the flag value from a string argument.
 func (is *ImageSpec) Set(value string) error {
-	is.flag = value
+	is.Flag = value
 	switch value {
-	case ImageSpecV1_1:
+	case ImageSpecV1_1, ImageSpecAuto:
 		is.PackVersion = oras.PackManifestVersion1_1
 	case ImageSpecV1_0:
 		is.PackVersion = oras.PackManifestVersion1_0
@@ -67,20 +68,21 @@ func (is *ImageSpec) Options() string {
 	return strings.Join([]string{
 		ImageSpecV1_1,
 		ImageSpecV1_0,
+		ImageSpecAuto,
 	}, ", ")
 }
 
 // String returns the string representation of the flag.
 func (is *ImageSpec) String() string {
-	return is.flag
+	return is.Flag
 }
 
 // ApplyFlags applies flags to a command flag set.
 func (is *ImageSpec) ApplyFlags(fs *pflag.FlagSet) {
-	// default to v1.1-rc.4
+	// default to auto
 	is.PackVersion = oras.PackManifestVersion1_1
-	defaultFlag := ImageSpecV1_1
-	fs.Var(is, "image-spec", fmt.Sprintf(`[Experimental] specify manifest type for building artifact. Options: %s (default %q)`, is.Options(), defaultFlag))
+	is.Flag = ImageSpecAuto
+	fs.Var(is, "image-spec", fmt.Sprintf(`[Experimental] specify manifest type for building artifact. Options: %s (default %q)`, is.Options(), ImageSpecAuto))
 }
 
 // DistributionSpec option struct which implements pflag.Value interface.

cmd/oras/root/push.go

@@ -108,6 +108,22 @@ Example - Push file "hi.txt" into an OCI image layout folder 'layout-dir' with t
 			if err := option.Parse(cmd, &opts); err != nil {
 				return err
 			}
+
+			if opts.manifestConfigRef != "" && opts.artifactType == "" {
+				switch opts.Flag {
+				case option.ImageSpecAuto:
+					// switch to v1.0 manifest since artifact type is suggested by OCI v1.1
+					// artifact guidance but is not presented
+					// see https://github.com/opencontainers/image-spec/blob/e7f7c0ca69b21688c3cea7c87a04e4503e6099e2/manifest.md?plain=1#L170
+					opts.PackVersion = oras.PackManifestVersion1_0
+				case option.ImageSpecV1_1:
+					return &oerrors.Error{
+						Err:            errors.New(`artifact type missing for OCI image-spec v1.1 artifacts`),
+						Recommendation: "set an artifact type via `--artifact-type` or consider image spec v1.0",
+					}
+				}
+			}
+
 			switch opts.PackVersion {
 			case oras.PackManifestVersion1_0:
 				if opts.manifestConfigRef != "" && opts.artifactType != "" {

test/e2e/suite/command/push.go

@@ -102,6 +102,16 @@ var _ = Describe("ORAS beginners:", func() {
 				MatchErrKeyWords("Error:", invalidFlag, "Available options: v1.1, v1.0").
 				Exec()
 		})
+
+		It("should fail if image spec v1.1 is used, with --config and without --artifactType", func() {
+			testRepo := pushTestRepo("v1-1/no-artifact-type")
+			subjectRef := RegistryRef(ZOTHost, testRepo, foobar.Tag)
+			imageSpecFlag := "v1.1"
+			ORAS("push", subjectRef, "--config", foobar.FileConfigName, Flags.ImageSpec, imageSpecFlag).
+				ExpectFailure().
+				MatchErrKeyWords("artifact type missing for OCI image-spec v1.1 artifacts").
+				Exec()
+		})
 	})
 })
 
@@ -233,6 +243,29 @@ var _ = Describe("Remote registry users:", func() {
 			}))
 		})
 
+		It("should pack with image spec v1.0 when --config is used, --artifact-type is not used, and --image-spec set to auto", func() {
+			repo := pushTestRepo("config/without/artifact/type")
+			configType := "my/config/type"
+			tempDir := PrepareTempFiles()
+
+			ORAS("push", RegistryRef(ZOTHost, repo, tag), "--config", fmt.Sprintf("%s:%s", foobar.FileConfigName, configType), foobar.FileBarName, "-v").
+				MatchStatus([]match.StateKey{
+					{Digest: foobar.FileConfigStateKey.Digest, Name: configType},
+					foobar.FileBarStateKey,
+				}, true, 2).
+				WithWorkDir(tempDir).Exec()
+			// validate
+			fetched := ORAS("manifest", "fetch", RegistryRef(ZOTHost, repo, tag)).Exec().Out.Contents()
+			var manifest ocispec.Manifest
+			Expect(json.Unmarshal(fetched, &manifest)).ShouldNot(HaveOccurred())
+			Expect(manifest.Config).Should(Equal(ocispec.Descriptor{
+				MediaType: configType,
+				Size:      int64(foobar.FileConfigSize),
+				Digest:    foobar.FileConfigDigest,
+			}))
+			Expect(manifest.ArtifactType).Should(Equal(""))
+		})
+
 		It("should push files with customized config file and mediatype", func() {
 			repo := pushTestRepo("config/mediatype")
 			configType := "config/type"