cmd/utils, pkg/utils: Beautify an error message for the image option

containers#937

src/cmd/utils.go

@@ -112,6 +112,16 @@ func createErrorInvalidImageForContainerName() error {
 	return errors.New(errMsg)
 }
 
+func createErrorInvalidImageWithoutBasename() error {
+	var builder strings.Builder
+	fmt.Fprintf(&builder, "invalid argument for '--image'\n")
+	fmt.Fprintf(&builder, "Images must have basenames.\n")
+	fmt.Fprintf(&builder, "Run '%s --help' for usage.", executableBase)
+
+	errMsg := builder.String()
+	return errors.New(errMsg)
+}
+
 func createErrorInvalidRelease(hint string) error {
 	var builder strings.Builder
 	fmt.Fprintf(&builder, "invalid argument for '--release'\n")
@@ -145,6 +155,9 @@ func handleResolveErrorForCLI(err error, containerArg, distro string) error {
 	} else if errors.Is(err, utils.ErrContainerNameFromImageInvalid) {
 		err := createErrorInvalidImageForContainerName()
 		return err
+	} else if errors.Is(err, utils.ErrImageWithoutBasename) {
+		err := createErrorInvalidImageWithoutBasename()
+		return err
 	} else {
 		var errParseRelease *utils.ParseReleaseError
 

src/pkg/utils/utils.go

@@ -129,6 +129,8 @@ var (
 	ErrContainerNameInvalid = errors.New("container name is invalid")
 
 	ErrContainerNameFromImageInvalid = errors.New("container name generated from image is invalid")
+
+	ErrImageWithoutBasename = errors.New("image does not have a basename")
 )
 
 func init() {
@@ -247,7 +249,7 @@ func GetCgroupsVersion() (int, error) {
 func getContainerNamePrefixForImage(image string) (string, error) {
 	basename := ImageReferenceGetBasename(image)
 	if basename == "" {
-		return "", fmt.Errorf("failed to get the basename of image %s", image)
+		return "", fmt.Errorf("%s: %w", image, ErrImageWithoutBasename)
 	}
 
 	for _, distroObj := range supportedDistros {