Refactor newClient in ctr

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/ctr/rootfs.go

@@ -22,34 +22,27 @@ var rootfsUnpackCommand = cli.Command{
 	Usage:     "unpack applies layers from a manifest to a snapshot",
 	ArgsUsage: "[flags] <digest>",
 	Flags:     snapshotterFlags,
-	Action: func(clicontext *cli.Context) error {
-		ctx, cancel := appContext(clicontext)
+	Action: func(context *cli.Context) error {
+		dgst, err := digest.Parse(context.Args().First())
+		if err != nil {
+			return err
+		}
+		client, ctx, cancel, err := newClient(context)
+		if err != nil {
+			return err
+		}
 		defer cancel()
-
-		dgst, err := digest.Parse(clicontext.Args().First())
-		if err != nil {
-			return err
-		}
-
 		log.G(ctx).Debugf("unpacking layers from manifest %s", dgst.String())
-
-		client, err := newClient(clicontext)
-		if err != nil {
-			return err
-		}
-
 		// TODO: Support unpack by name
-
 		images, err := client.ListImages(ctx)
 		if err != nil {
 			return err
 		}
-
 		var unpacked bool
 		for _, image := range images {
 			if image.Target().Digest == dgst {
 				fmt.Printf("unpacking %s (%s)...", dgst, image.Target().MediaType)
-				if err := image.Unpack(ctx, clicontext.String("snapshotter")); err != nil {
+				if err := image.Unpack(ctx, context.String("snapshotter")); err != nil {
 					fmt.Println()
 					return err
 				}
@@ -61,10 +54,8 @@ var rootfsUnpackCommand = cli.Command{
 		if !unpacked {
 			return errors.New("manifest not found")
 		}
-
 		// TODO: Get rootfs from Image
 		//log.G(ctx).Infof("chain ID: %s", chainID.String())
-
 		return nil
 	},
 }