[WIP] Add digest-only option

cmd/oras/internal/option/pusher.go

@@ -0,0 +1,49 @@
+/*
+Copyright The ORAS Authors.
+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 option
+
+import (
+	"context"
+	"os"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/spf13/pflag"
+	"oras.land/oras-go/v2/content"
+)
+
+// Pusher option struct.
+type Pusher struct {
+	DigestOnly     bool
+	ManifestExport string
+}
+
+// ApplyFlags applies flags to a command flag set.
+func (opts *Pusher) ApplyFlags(fs *pflag.FlagSet) {
+	fs.BoolVarP(&opts.DigestOnly, "digest-only", "", false, "will manifest(s) be pushed without tagging")
+	fs.StringVarP(&opts.ManifestExport, "export-manifest", "", "", "export the pushed manifest")
+}
+
+// ExportManifest saves the pushed manifest to a local file.
+func (opts *Pusher) ExportManifest(ctx context.Context, pushed ocispec.Descriptor, pushedTo content.Fetcher) error {
+	if opts.ManifestExport == "" {
+		return nil
+	}
+	manifestBytes, err := content.FetchAll(ctx, pushedTo, pushed)
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(opts.ManifestExport, manifestBytes, 0666)
+}

cmd/oras/push.go

@@ -25,7 +25,6 @@ import (
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/spf13/cobra"
 	"oras.land/oras-go/v2"
-	"oras.land/oras-go/v2/content"
 	"oras.land/oras-go/v2/content/file"
 	"oras.land/oras/cmd/oras/internal/display"
 	"oras.land/oras/cmd/oras/internal/option"
@@ -40,12 +39,12 @@ const (
 type pushOptions struct {
 	option.Common
 	option.Remote
+	option.Pusher
 
 	targetRef              string
 	fileRefs               []string
 	pathValidationDisabled bool
 	manifestAnnotations    string
-	manifestExport         string
 	manifestConfigRef      string
 }
 
@@ -88,7 +87,6 @@ Example - Push file to the HTTP registry:
 	cmd.Flags().StringVarP(&opts.manifestAnnotations, "manifest-annotations", "", "", "manifest annotation file")
 	cmd.Flags().BoolVarP(&opts.pathValidationDisabled, "disable-path-validation", "", false, "skip path validation")
 	cmd.Flags().StringVarP(&opts.manifestConfigRef, "manifest-config", "", "", "manifest config file")
-	cmd.Flags().StringVarP(&opts.manifestExport, "export-manifest", "", "", "export the pushed manifest")
 
 	option.ApplyFlags(&opts, cmd.Flags())
 	return cmd
@@ -97,11 +95,6 @@ Example - Push file to the HTTP registry:
 func runPush(opts pushOptions) error {
 	ctx, _ := opts.SetLoggerLevel()
 
-	dst, err := opts.NewRepository(opts.targetRef, opts.Common)
-	if err != nil {
-		return err
-	}
-
 	// Load annotations
 	var annotations map[string]map[string]string
 	if opts.manifestAnnotations != "" {
@@ -134,7 +127,13 @@ func runPush(opts pushOptions) error {
 	if err != nil {
 		return err
 	}
-	if tag := dst.Reference.Reference; tag == "" {
+
+	// Push
+	dst, err := opts.NewRepository(opts.targetRef, opts.Common)
+	if err != nil {
+		return err
+	}
+	if tag := dst.Reference.Reference; tag == "" || opts.DigestOnly {
 		err = oras.CopyGraph(ctx, store, dst, desc, copyOptions.CopyGraphOptions)
 	} else {
 		desc, err = oras.Copy(ctx, store, tagStaged, dst, tag, copyOptions)
@@ -146,17 +145,8 @@ func runPush(opts pushOptions) error {
 	fmt.Println("Pushed", opts.targetRef)
 	fmt.Println("Digest:", desc.Digest)
 
-	// export manifest
-	if opts.manifestExport != "" {
-		manifestBytes, err := content.FetchAll(ctx, store, desc)
-		if err != nil {
-			return err
-		}
-		if err = os.WriteFile(opts.manifestExport, manifestBytes, 0666); err != nil {
-			return err
-		}
-	}
-	return nil
+	// Export manifest
+	return opts.ExportManifest(ctx, desc, store)
 }
 
 func decodeJSON(filename string, v interface{}) error {