accepts attachment-tag-prefix for cosign copy

cmd/cosign/cli/copy/copy.go

@@ -49,17 +49,24 @@ func CopyCmd(ctx context.Context, regOpts options.RegistryOptions, srcImg, dstIm
 	}
 	dstRepoRef := dstRef.Context()
 
+	ociRemoteOpts, err := regOpts.ClientOpts(ctx)
+	if err != nil {
+		return err
+	}
+
 	remoteOpts := regOpts.GetRegistryClientOpts(ctx)
 
 	pusher, err := remote.NewPusher(remoteOpts...)
 	if err != nil {
 		return err
 	}
 
+	ociRemoteOpts = append(ociRemoteOpts, ociremote.WithRemoteOptions(remoteOpts...))
+
 	g, gctx := errgroup.WithContext(ctx)
 	g.SetLimit(runtime.GOMAXPROCS(0))
 
-	root, err := ociremote.SignedEntity(srcRef, ociremote.WithRemoteOptions(remoteOpts...))
+	root, err := ociremote.SignedEntity(srcRef, ociRemoteOpts...)
 	if err != nil {
 		return err
 	}
@@ -73,7 +80,7 @@ func CopyCmd(ctx context.Context, regOpts options.RegistryOptions, srcImg, dstIm
 		srcDigest := srcRepoRef.Digest(h.String())
 
 		copyTag := func(tm tagMap) error {
-			src, err := tm(srcDigest, ociremote.WithRemoteOptions(remoteOpts...))
+			src, err := tm(srcDigest, ociRemoteOpts...)
 			if err != nil {
 				return err
 			}
@@ -102,6 +109,7 @@ func CopyCmd(ctx context.Context, regOpts options.RegistryOptions, srcImg, dstIm
 		// Copy the entity itself.
 		g.Go(func() error {
 			dst := dstRepoRef.Tag(srcDigest.Identifier())
+			dst = dst.Tag(fmt.Sprint(regOpts.RefOpts.TagPrefix, h.Algorithm, "-", h.Hex))
 			return remoteCopy(ctx, pusher, srcDigest, dst, force, remoteOpts...)
 		})
 

cmd/cosign/cli/copy/copy_test.go

@@ -0,0 +1,40 @@
+// Copyright 2023 the Sigstore 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 copy
+
+import (
+	"context"
+	"testing"
+
+	"github.com/sigstore/cosign/v2/cmd/cosign/cli/options"
+)
+
+func TestCopyAttachmentTagPrefix(t *testing.T) {
+	ctx := context.Background()
+
+	refOpts := options.ReferenceOptions{
+		TagPrefix: "test-tag",
+	}
+
+	srcImg := "alpine"
+	destImg := "test-alpine"
+
+	err := CopyCmd(ctx, options.RegistryOptions{
+		RefOpts: refOpts,
+	}, srcImg, destImg, false, true)
+	if err == nil {
+		t.Fatal("failed to copy with attachment-tag-prefix")
+	}
+}