feat: tag image using Transfer api

Signed-off-by: Jian Zeng <anonymousknight96@gmail.com>

cmd/ctr/commands/images/tag.go

@@ -19,9 +19,11 @@ package images
 import (
 	"fmt"
 
+	"github.com/urfave/cli"
+
 	"github.com/containerd/containerd/cmd/ctr/commands"
 	"github.com/containerd/containerd/errdefs"
-	"github.com/urfave/cli"
+	"github.com/containerd/containerd/pkg/transfer/image"
 )
 
 var tagCommand = cli.Command{
@@ -34,6 +36,10 @@ var tagCommand = cli.Command{
 			Name:  "force",
 			Usage: "Force target_ref to be created, regardless if it already exists",
 		},
+		cli.BoolTFlag{
+			Name:  "local",
+			Usage: "run tag locally rather than through transfer API",
+		},
 	},
 	Action: func(context *cli.Context) error {
 		var (
@@ -52,6 +58,17 @@ var tagCommand = cli.Command{
 		}
 		defer cancel()
 
+		if !context.BoolT("local") {
+			for _, targetRef := range context.Args()[1:] {
+				err = client.Transfer(ctx, image.NewStore(ref), image.NewStore(targetRef))
+				if err != nil {
+					return err
+				}
+				fmt.Println(targetRef)
+			}
+			return nil
+		}
+
 		ctx, done, err := client.WithLease(ctx)
 		if err != nil {
 			return err