perf: save auth requests for push and attach (#1097)

Signed-off-by: Sylvia Lei <lixlei@microsoft.com>

cmd/oras/root/attach.go

@@ -26,8 +26,11 @@ import (
 	"oras.land/oras-go/v2"
 	"oras.land/oras-go/v2/content"
 	"oras.land/oras-go/v2/content/file"
+	"oras.land/oras-go/v2/registry/remote"
+	"oras.land/oras-go/v2/registry/remote/auth"
 	"oras.land/oras/cmd/oras/internal/option"
 	"oras.land/oras/internal/graph"
+	"oras.land/oras/internal/registryutil"
 )
 
 type attachOptions struct {
@@ -116,6 +119,11 @@ func runAttach(ctx context.Context, opts attachOptions) error {
 	if err := opts.EnsureReferenceNotEmpty(); err != nil {
 		return err
 	}
+	if repo, ok := dst.(*remote.Repository); ok {
+		// add both pull and push scope hints for dst repository
+		// to save potential push-scope token requests during copy
+		ctx = registryutil.WithScopeHint(ctx, repo.Reference, auth.ActionPull, auth.ActionPush)
+	}
 	subject, err := dst.Resolve(ctx, opts.Reference)
 	if err != nil {
 		return err

cmd/oras/root/push.go

@@ -28,10 +28,13 @@ import (
 	"oras.land/oras-go/v2/content"
 	"oras.land/oras-go/v2/content/file"
 	"oras.land/oras-go/v2/content/memory"
+	"oras.land/oras-go/v2/registry/remote"
+	"oras.land/oras-go/v2/registry/remote/auth"
 	"oras.land/oras/cmd/oras/internal/display"
 	"oras.land/oras/cmd/oras/internal/fileref"
 	"oras.land/oras/cmd/oras/internal/option"
 	"oras.land/oras/internal/contentutil"
+	"oras.land/oras/internal/registryutil"
 )
 
 type pushOptions struct {
@@ -181,6 +184,12 @@ func runPush(ctx context.Context, opts pushOptions) error {
 	union := contentutil.MultiReadOnlyTarget(memoryStore, store)
 	updateDisplayOption(&copyOptions.CopyGraphOptions, union, opts.Verbose)
 	copy := func(root ocispec.Descriptor) error {
+		if repo, ok := dst.(*remote.Repository); ok {
+			// add both pull and push scope hints for dst repository
+			// to save potential push-scope token requests during copy
+			ctx = registryutil.WithScopeHint(ctx, repo.Reference, auth.ActionPull, auth.ActionPush)
+		}
+
 		if tag := opts.Reference; tag == "" {
 			err = oras.CopyGraph(ctx, union, dst, root, copyOptions.CopyGraphOptions)
 		} else {

internal/registryutil/auth.go

@@ -0,0 +1,29 @@
+/*
+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 registryutil
+
+import (
+	"context"
+
+	"oras.land/oras-go/v2/registry"
+	"oras.land/oras-go/v2/registry/remote/auth"
+)
+
+// WithScopeHint adds a hinted scope to the context.
+func WithScopeHint(ctx context.Context, ref registry.Reference, actions ...string) context.Context {
+	scope := auth.ScopeRepository(ref.Repository, actions...)
+	return auth.AppendScopes(ctx, scope)
+}