GODT-2013: CLI flag for frontend is required.

Other: removed --ni flag alias.

internal/app/base/base.go

@@ -69,12 +69,13 @@ const (
 	flagMemProfileShort = "m"
 	flagLogLevel        = "log-level"
 	flagLogLevelShort   = "l"
-	// FlagCLI indicate to start with command line interface.
-	FlagCLI      = "cli"
-	flagCLIShort = "c"
-	flagRestart  = "restart"
-	FlagLauncher = "launcher"
-	FlagNoWindow = "no-window"
+	FlagGRPC            = "grpc" // FlagGRPC starts the gRPC frontend
+	FlagGRPCShort       = "g"
+	FlagCLI             = "cli" // FlagCLI indicate to start with command line interface.
+	flagCLIShort        = "c"
+	flagRestart         = "restart"
+	FlagLauncher        = "launcher"
+	FlagNoWindow        = "no-window"
 )
 
 type Base struct {
@@ -299,6 +300,11 @@ func (b *Base) NewApp(mainLoop func(*Base, *cli.Context) error) *cli.App {
 			Aliases: []string{flagLogLevelShort},
 			Usage:   "Set the log level (one of panic, fatal, error, warn, info, debug)",
 		},
+		&cli.BoolFlag{
+			Name:    FlagGRPC,
+			Aliases: []string{FlagGRPCShort},
+			Usage:   "Start the gRPC service",
+		},
 		&cli.BoolFlag{
 			Name:    FlagCLI,
 			Aliases: []string{flagCLIShort},

internal/app/bridge/bridge.go

@@ -40,10 +40,10 @@ import (
 )
 
 const (
-	flagLogIMAP        = "log-imap"
-	flagLogSMTP        = "log-smtp"
-	flagNonInteractive = "noninteractive"
-
+	flagLogIMAP             = "log-imap"
+	flagLogSMTP             = "log-smtp"
+	flagNonInteractive      = "noninteractive"
+	flagNonInteractiveShort = "n"
 	// Memory cache was estimated by empirical usage in the past, and it was set to 100MB.
 	// NOTE: This value must not be less than maximal size of one email (~30MB).
 	inMemoryCacheLimit = 100 * (1 << 20)
@@ -62,8 +62,9 @@ func New(base *base.Base) *cli.App {
 			Usage: "Enable logging of SMTP communications (may contain decrypted data!)",
 		},
 		&cli.BoolFlag{
-			Name:  flagNonInteractive,
-			Usage: "Start Bridge entirely non-interactively",
+			Name:    flagNonInteractive,
+			Aliases: []string{flagNonInteractiveShort},
+			Usage:   "Start Bridge entirely non-interactively",
 		},
 	}...)
 
@@ -72,6 +73,11 @@ func New(base *base.Base) *cli.App {
 
 func main(b *base.Base, c *cli.Context) error { //nolint:funlen
 	frontendType := getFrontendTypeFromCLIParams(c)
+	if frontendType == frontend.Unknown {
+		_ = cli.ShowAppHelp(c)
+		return errors.New("no frontend was specified. Use --grpc, --cli or --noninteractive")
+	}
+
 	f := frontend.New(
 		frontendType,
 		!c.Bool(base.FlagNoWindow),
@@ -171,12 +177,14 @@ func main(b *base.Base, c *cli.Context) error { //nolint:funlen
 
 func getFrontendTypeFromCLIParams(c *cli.Context) frontend.Type {
 	switch {
+	case c.Bool(base.FlagGRPC):
+		return frontend.GRPC
 	case c.Bool(base.FlagCLI):
 		return frontend.CLI
 	case c.Bool(flagNonInteractive):
 		return frontend.NonInteractive
 	default:
-		return frontend.GRPC
+		return frontend.Unknown
 	}
 }
 

internal/frontend/bridge-gui/bridge-gui/main.cpp

@@ -200,7 +200,7 @@ void launchBridge(QStringList const &args)
     else
         app().log().debug(QString("Bridge executable path: %1").arg(QDir::toNativeSeparators(bridgeExePath)));
 
-    overseer = std::make_unique<Overseer>(new ProcessMonitor(bridgeExePath, args, nullptr), nullptr);
+    overseer = std::make_unique<Overseer>(new ProcessMonitor(bridgeExePath, QStringList("--grpc") + args, nullptr), nullptr);
     overseer->startWorker(true);
 }
 

internal/frontend/frontend.go

@@ -25,6 +25,7 @@ import (
 	"github.com/ProtonMail/proton-bridge/v2/internal/locations"
 	"github.com/ProtonMail/proton-bridge/v2/internal/updater"
 	"github.com/ProtonMail/proton-bridge/v2/pkg/listener"
+	"github.com/sirupsen/logrus"
 )
 
 // Type describes the available types of frontend.
@@ -34,6 +35,7 @@ const (
 	CLI Type = iota
 	GRPC
 	NonInteractive
+	Unknown
 )
 
 type Frontend interface {
@@ -45,7 +47,7 @@ type Frontend interface {
 	WaitUntilFrontendIsReady()
 }
 
-// New returns initialized frontend based on `frontendType`, which can be `CLI` or `GRPC`.
+// New returns initialized frontend based on `frontendType`, which can be `CLI` or `GRPC`. Non-interactive will return a nil frontend.
 func New(
 	frontendType Type,
 	showWindowOnStart bool,
@@ -75,9 +77,13 @@ func New(
 		)
 
 	case NonInteractive:
+		return nil
+
+	case Unknown:
 		fallthrough
 
 	default:
-		return nil
+		logrus.Panicf("Unexpected frontend value %v", frontendType)
+		return nil // return statement is required by compiler, although the above call will panic.
 	}
 }