feat: nctl auth login in non-interactive env and without set token sh…

…ould not block

If you execute `nctl auth login` in a non-interactive environment (e.g. CI/CD)
and forget to set `--api-token`, the browser should not try to open - you
should see an error message instead.

auth/login.go

@@ -58,6 +58,10 @@ func (l *LoginCmd) Run(ctx context.Context, command string, tk api.TokenGetter)
 		return login(ctx, cfg, loadingRules.GetDefaultFilename(), userInfo.User, "", project(l.Organization))
 	}
 
+	if !format.IsInteractiveEnvironment(os.Stdout) {
+		return fmt.Errorf("a static API token is required in non-interactive envirtonments")
+	}
+
 	usePKCE := true
 
 	token, err := tk.GetTokenString(ctx, l.IssuerURL, l.ClientID, usePKCE)

internal/format/print.go

@@ -193,11 +193,7 @@ func getPrinter(out io.Writer) (printer.Printer, error) {
 	p := printer.Printer{
 		LineNumber: false,
 	}
-	f, isFile := out.(*os.File)
-	if !isFile {
-		return p, nil
-	}
-	if isatty.IsTerminal(f.Fd()) || isatty.IsCygwinTerminal(f.Fd()) {
+	if IsInteractiveEnvironment(out) {
 		p.Bool = printerProperty(&printer.Property{
 			Prefix: format(color.FgHiMagenta),
 			Suffix: format(color.Reset),
@@ -218,6 +214,14 @@ func getPrinter(out io.Writer) (printer.Printer, error) {
 	return p, nil
 }
 
+func IsInteractiveEnvironment(out io.Writer) bool {
+	f, isFile := out.(*os.File)
+	if !isFile {
+		return false
+	}
+	return isatty.IsTerminal(f.Fd()) || isatty.IsCygwinTerminal(f.Fd())
+}
+
 // stripObj removes some fields which simply add clutter to the yaml output.
 // The object should still be applyable afterwards as just defaults and
 // computed fields get removed.