Improve the error message when running nested inside a non-Toolbx con…

…tainer

Fixes issue #1183

Signed-off-by: Nieves Montero <nmontero@redhat.com>

src/cmd/root.go

@@ -142,6 +142,10 @@ func preRun(cmd *cobra.Command, args []string) error {
 		if _, err := validateSubIDRanges(cmd, args, currentUser); err != nil {
 			return err
 		}
+	} else {
+		if !utils.IsInsideToolboxContainer() {
+			return createErrorNonToolboxContainer()
+		}
 	}
 
 	toolboxPath := os.Getenv("TOOLBOX_PATH")

src/cmd/utils.go

@@ -138,6 +138,16 @@ func createErrorInvalidRelease(hint string) error {
 	return errors.New(errMsg)
 }
 
+func createErrorNonToolboxContainer() error {
+	var builder strings.Builder
+	fmt.Fprintf(&builder, "this is not a Toolbox container.\n")
+	fmt.Fprintf(&builder, "Toolbox is only meant to work with Toolbox containers.\n")
+	fmt.Fprintf(&builder, "Run '%s --help' for usage.", executableBase)
+
+	errMsg := builder.String()
+	return errors.New(errMsg)
+}
+
 func getUsageForCommonCommands() string {
 	var builder strings.Builder
 	fmt.Fprintf(&builder, "create    Create a new toolbox container\n")