feat: export images using Transfer api

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

cmd/ctr/commands/images/export.go

@@ -22,11 +22,15 @@ import (
 	"io"
 	"os"
 
-	"github.com/containerd/containerd/cmd/ctr/commands"
-	"github.com/containerd/containerd/images/archive"
-	"github.com/containerd/containerd/platforms"
 	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/urfave/cli"
+
+	"github.com/containerd/containerd/cmd/ctr/commands"
+	"github.com/containerd/containerd/images/archive"
+	"github.com/containerd/containerd/pkg/transfer"
+	tarchive "github.com/containerd/containerd/pkg/transfer/archive"
+	"github.com/containerd/containerd/pkg/transfer/image"
+	"github.com/containerd/containerd/platforms"
 )
 
 var exportCommand = cli.Command{
@@ -58,6 +62,10 @@ When '--all-platforms' is given all images in a manifest list must be available.
 			Name:  "all-platforms",
 			Usage: "Exports content from all platforms",
 		},
+		cli.BoolTFlag{
+			Name:  "local",
+			Usage: "run export locally rather than through transfer API",
+		},
 	},
 	Action: func(context *cli.Context) error {
 		var (
@@ -69,6 +77,56 @@ When '--all-platforms' is given all images in a manifest list must be available.
 			return errors.New("please provide both an output filename and an image reference to export")
 		}
 
+		client, ctx, cancel, err := commands.NewClient(context)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+
+		var w io.WriteCloser
+		if out == "-" {
+			w = os.Stdout
+		} else {
+			w, err = os.Create(out)
+			if err != nil {
+				return err
+			}
+		}
+		defer w.Close()
+
+		if !context.BoolT("local") {
+			pf, done := ProgressHandler(ctx, os.Stdout)
+			defer done()
+
+			var specified []ocispec.Platform
+			if pss := context.StringSlice("platform"); len(pss) > 0 {
+				for _, ps := range pss {
+					p, err := platforms.Parse(ps)
+					if err != nil {
+						return fmt.Errorf("invalid platform %q: %w", ps, err)
+					}
+					specified = append(specified, p)
+				}
+			}
+
+			err := client.Transfer(ctx,
+				image.NewStore(""), // a dummy image store
+				tarchive.NewImageExportStream(w, "", tarchive.ExportOptions{
+					Images:               images,
+					Platforms:            specified,
+					AllPlatforms:         context.Bool("all-platforms"),
+					SkipNonDistributable: context.Bool("skip-non-distributable"),
+					SkipDockerManifest:   context.Bool("skip-manifest-json"),
+				}),
+				transfer.WithProgress(pf),
+			)
+			if err != nil {
+				return err
+			}
+
+			return nil
+		}
+
 		if pss := context.StringSlice("platform"); len(pss) > 0 {
 			var all []ocispec.Platform
 			for _, ps := range pss {
@@ -95,28 +153,11 @@ When '--all-platforms' is given all images in a manifest list must be available.
 			exportOpts = append(exportOpts, archive.WithSkipNonDistributableBlobs())
 		}
 
-		client, ctx, cancel, err := commands.NewClient(context)
-		if err != nil {
-			return err
-		}
-		defer cancel()
-
 		is := client.ImageService()
 		for _, img := range images {
 			exportOpts = append(exportOpts, archive.WithImage(is, img))
 		}
 
-		var w io.WriteCloser
-		if out == "-" {
-			w = os.Stdout
-		} else {
-			w, err = os.Create(out)
-			if err != nil {
-				return err
-			}
-		}
-		defer w.Close()
-
 		return client.Export(ctx, w, exportOpts...)
 	},
 }