bib: make --progress=auto the default

Previously an empty string in `--progress` meant to "auto-select".
But that is not super intuitive so this commit makes it explicit
using "auto".

Thanks to Achilleas for the suggestion.

README.md

@@ -138,7 +138,7 @@ Flags:
 | Argument          | Description                                                                                               | Default Value |
 |-------------------|-----------------------------------------------------------------------------------------------------------|:-------------:|
 | **--chown**       | chown the output directory to match the specified UID:GID                                                 |       ❌      |
-| **--progress**   | Show progress in the given format, supported: plain,term,debug. If empty it is auto-detected               |       ❌      |
+| **--progress**   | Show progress in the given format, supported: plain,term,debug. If empty it is auto-detected               |   `auto`      |
 | **--rootfs**      | Root filesystem type. Overrides the default from the source container. Supported values: ext4, xfs, btrfs |       ❌      |
 | **--tls-verify**  | Require HTTPS and verify certificates when contacting registries                                          |    `true`     |
 | **--type**        | [Image type](#-image-types) to build                                                                      |    `qcow2`    |

bib/cmd/bootc-image-builder/main.go

@@ -628,9 +628,9 @@ func buildCobraCmdline() (*cobra.Command, error) {
 	rootCmd.PersistentFlags().StringVar(&rootLogLevel, "log-level", "", "logging level (debug, info, error); default error")
 
 	buildCmd := &cobra.Command{
-		Use:                   "build IMAGE_NAME",
-		Short:                 rootCmd.Long + " (default command)",
-		Long:                  rootCmd.Long + "\n" +
+		Use:   "build IMAGE_NAME",
+		Short: rootCmd.Long + " (default command)",
+		Long: rootCmd.Long + "\n" +
 			"(default action if no command is given)\n" +
 			"IMAGE_NAME: container image to build into a bootable image",
 		Args:                  cobra.ExactArgs(1),
@@ -691,7 +691,7 @@ func buildCobraCmdline() (*cobra.Command, error) {
 	buildCmd.Flags().String("output", ".", "artifact output directory")
 	buildCmd.Flags().String("store", "/store", "osbuild store for intermediate pipeline trees")
 	//TODO: add json progress for higher level tools like "podman bootc"
-	buildCmd.Flags().String("progress", "", "type of progress bar to use (e.g. plain,term)")
+	buildCmd.Flags().String("progress", "auto", "type of progress bar to use (e.g. plain,term)")
 	// flag rules
 	for _, dname := range []string{"output", "store", "rpmmd"} {
 		if err := buildCmd.MarkFlagDirname(dname); err != nil {

bib/internal/progress/progress.go

@@ -72,7 +72,7 @@ var isattyIsTerminal = isatty.IsTerminal
 // New creates a new progressbar based on the requested type
 func New(typ string) (ProgressBar, error) {
 	switch typ {
-	case "":
+	case "", "auto":
 		// autoselect based on if we are on an interactive
 		// terminal, use plain progress for scripts
 		if isattyIsTerminal(os.Stdin.Fd()) {

bib/internal/progress/progress_test.go

@@ -125,7 +125,7 @@ func TestProgressNewAutoselect(t *testing.T) {
 		})
 		defer restore()
 
-		pb, err := progress.New("")
+		pb, err := progress.New("auto")
 		assert.NoError(t, err)
 		assert.Equal(t, reflect.TypeOf(pb), reflect.TypeOf(tc.expected), fmt.Sprintf("[%v] %T not the expected %T", tc.onTerm, pb, tc.expected))
 	}