remotes/ctr: allow to limit max concurrent uploads like downloads

Also add flags for push/pull subcommand to limit max concurrent
uploads/downloads.

Signed-off-by: Wei Fu <fuweid89@gmail.com>

cmd/ctr/commands/content/fetch.go

@@ -109,7 +109,7 @@ type FetchConfig struct {
 	Platforms []string
 	// Whether or not download all metadata
 	AllMetadata bool
-	// RemoteOpts is not used by ctr, but can be used by other CLI tools
+	// RemoteOpts to configure object resolutions and transfers with remote content providers
 	RemoteOpts []containerd.RemoteOpt
 	// TraceHTTP writes DNS and connection information to the log when dealing with a container registry
 	TraceHTTP bool
@@ -145,6 +145,16 @@ func NewFetchConfig(ctx context.Context, clicontext *cli.Context) (*FetchConfig,
 		config.AllMetadata = true
 	}
 
+	if clicontext.IsSet("max-concurrent-downloads") {
+		mcd := clicontext.Int("max-concurrent-downloads")
+		config.RemoteOpts = append(config.RemoteOpts, containerd.WithMaxConcurrentDownloads(mcd))
+	}
+
+	if clicontext.IsSet("max-concurrent-uploaded-layers") {
+		mcu := clicontext.Int("max-concurrent-uploaded-layers")
+		config.RemoteOpts = append(config.RemoteOpts, containerd.WithMaxConcurrentUploadedLayers(mcu))
+	}
+
 	return config, nil
 }
 

cmd/ctr/commands/images/pull.go

@@ -63,6 +63,10 @@ command. As part of this process, we do the following:
 			Name:  "print-chainid",
 			Usage: "Print the resulting image's chain ID",
 		},
+		cli.IntFlag{
+			Name:  "max-concurrent-downloads",
+			Usage: "Set the max concurrent downloads for each pull",
+		},
 	),
 	Action: func(context *cli.Context) error {
 		var (

cmd/ctr/commands/images/push.go

@@ -64,6 +64,9 @@ var pushCommand = cli.Command{
 		Name:  "platform",
 		Usage: "push content from a specific platform",
 		Value: &cli.StringSlice{},
+	}, cli.IntFlag{
+		Name:  "max-concurrent-uploaded-layers",
+		Usage: "Set the max concurrent uploaded layers for each push",
 	}),
 	Action: func(context *cli.Context) error {
 		var (
@@ -144,10 +147,17 @@ var pushCommand = cli.Command{
 				return nil, nil
 			})
 
-			return client.Push(ctx, ref, desc,
+			ropts := []containerd.RemoteOpt{
 				containerd.WithResolver(resolver),
 				containerd.WithImageHandler(jobHandler),
-			)
+			}
+
+			if context.IsSet("max-concurrent-uploaded-layers") {
+				mcu := context.Int("max-concurrent-uploaded-layers")
+				ropts = append(ropts, containerd.WithMaxConcurrentUploadedLayers(mcu))
+			}
+
+			return client.Push(ctx, ref, desc, ropts...)
 		})
 
 		// don't show progress if debug mode is set