adds quiet option for ref

Signed-off-by: Mike Brown <brownwm@us.ibm.com>

cmd/ctr/commands/images/images.go

@@ -202,10 +202,16 @@ var checkCommand = cli.Command{
 	Usage:       "check existing images to ensure all content is available locally",
 	ArgsUsage:   "[flags] [<filter>, ...]",
 	Description: "check existing images to ensure all content is available locally",
-	Flags:       commands.SnapshotterFlags,
+	Flags: append([]cli.Flag{
+		cli.BoolFlag{
+			Name:  "quiet, q",
+			Usage: "print only the ready image refs (fully downloaded and unpacked)",
+		},
+	}, commands.SnapshotterFlags...),
 	Action: func(context *cli.Context) error {
 		var (
 			exitErr error
+			quiet   = context.Bool("quiet")
 		)
 		client, ctx, cancel, err := commands.NewClient(context)
 		if err != nil {
@@ -226,7 +232,9 @@ var checkCommand = cli.Command{
 		}
 
 		var tw = tabwriter.NewWriter(os.Stdout, 1, 8, 1, ' ', 0)
+		if !quiet {
 			fmt.Fprintln(tw, "REF\tTYPE\tDIGEST\tSTATUS\tSIZE\tUNPACKED\t")
+		}
 
 		for _, image := range imageList {
 			var (
@@ -234,6 +242,7 @@ var checkCommand = cli.Command{
 				size         string
 				requiredSize int64
 				presentSize  int64
+				complete     bool = true
 			)
 
 			available, required, present, missing, err := images.Check(ctx, contentStore, image.Target(), platforms.Default())
@@ -243,6 +252,7 @@ var checkCommand = cli.Command{
 				}
 				log.G(ctx).WithError(err).Errorf("unable to check %v", image.Name())
 				status = "error"
+				complete = false
 			}
 
 			if status != "error" {
@@ -256,6 +266,7 @@ var checkCommand = cli.Command{
 
 				if len(missing) > 0 {
 					status = "incomplete"
+					complete = false
 				}
 
 				if available {
@@ -264,6 +275,7 @@ var checkCommand = cli.Command{
 				} else {
 					status = fmt.Sprintf("unavailable (%v/?)", len(present))
 					size = fmt.Sprintf("%v/?", progress.Bytes(presentSize))
+					complete = false
 				}
 			} else {
 				size = "-"
@@ -277,6 +289,7 @@ var checkCommand = cli.Command{
 				log.G(ctx).WithError(err).Errorf("unable to check unpack for %v", image.Name())
 			}
 
+			if !quiet {
 				fmt.Fprintf(tw, "%v\t%v\t%v\t%v\t%v\t%t\n",
 					image.Name(),
 					image.Target().MediaType,
@@ -284,9 +297,15 @@ var checkCommand = cli.Command{
 					status,
 					size,
 					unpacked)
+			} else {
+				if complete {
+					fmt.Println(image.Name())
 				}
+			}
+		}
+		if !quiet {
 			tw.Flush()
-
+		}
 		return exitErr
 	},
 }