[v17] Fix printing empty usage and terminate CLI for parsing global flags

lib/utils/cli.go

@@ -377,6 +377,18 @@ func InitCLIParser(appName, appHelp string) (app *kingpin.Application) {
 	return app.UsageTemplate(createUsageTemplate())
 }
 
+// InitHiddenCLIParser initializes a `kingpin.Application` that does not terminate the application
+// or write any usage information to os.Stdout. Can be used in scenarios where multiple `kingpin.Application`
+// instances are needed without interfering with subsequent parsing. Usage output is completely suppressed,
+// and the default global `--help` flag is ignored to prevent the application from exiting.
+func InitHiddenCLIParser() (app *kingpin.Application) {
+	app = kingpin.New("", "")
+	app.UsageWriter(io.Discard)
+	app.Terminate(func(i int) {})
+
+	return app
+}
+
 // createUsageTemplate creates an usage template for kingpin applications.
 func createUsageTemplate(opts ...func(*usageTemplateOptions)) string {
 	opt := &usageTemplateOptions{

tool/tctl/common/tctl.go

@@ -90,12 +90,11 @@ func TryRun(ctx context.Context, commands []CLICommand, args []string) error {
 	utils.InitLogger(utils.LoggingForCLI, slog.LevelWarn)
 
 	var ccf tctlcfg.GlobalCLIFlags
-	muApp := utils.InitCLIParser("tctl", GlobalHelpString)
+	muApp := utils.InitHiddenCLIParser()
 	muApp.Flag("auth-server",
 		fmt.Sprintf("Attempts to connect to specific auth/proxy address(es) instead of local auth [%v]", defaults.AuthConnectAddr().Addr)).
 		Envar(authAddrEnvVar).
 		StringsVar(&ccf.AuthServerAddr)
-
 	// We need to parse the arguments before executing managed updates to identify
 	// the profile name and the required version for the current cluster.
 	// All other commands and flags may change between versions, so full parsing
@@ -104,9 +103,6 @@ func TryRun(ctx context.Context, commands []CLICommand, args []string) error {
 		slog.WarnContext(ctx, "can't identify current profile", "error", err)
 	}
 
-	// app is the command line parser
-	app := utils.InitCLIParser("tctl", GlobalHelpString)
-
 	// cfg (teleport auth server configuration) is going to be shared by all
 	// commands
 	cfg := servicecfg.MakeDefaultConfig()
@@ -124,6 +120,9 @@ func TryRun(ctx context.Context, commands []CLICommand, args []string) error {
 		return trace.Wrap(err)
 	}
 
+	// app is the command line parser
+	app := utils.InitCLIParser("tctl", GlobalHelpString)
+
 	// Each command will add itself to the CLI parser.
 	for i := range commands {
 		commands[i].Initialize(app, &ccf, cfg)

tool/tsh/common/tsh.go

@@ -821,10 +821,9 @@ func Run(ctx context.Context, args []string, opts ...CliOption) error {
 	// All other commands and flags may change between versions, so full parsing
 	// should be performed only after managed updates are applied.
 	var proxyArg string
-	muApp := utils.InitCLIParser("tsh", "")
+	muApp := utils.InitHiddenCLIParser()
 	muApp.Flag("proxy", "Teleport proxy address").Envar(proxyEnvVar).Hidden().StringVar(&proxyArg)
 	muApp.Flag("check-update", "Check for availability of managed update.").Envar(toolsCheckUpdateEnvVar).Hidden().BoolVar(&cf.checkManagedUpdates)
-
 	if _, err := muApp.Parse(utils.FilterArguments(args, muApp.Model())); err != nil {
 		slog.WarnContext(ctx, "can't identify current profile", "error", err)
 	}

tool/tsh/common/tsh_test.go

@@ -461,6 +461,29 @@ func TestNoEnvVars(t *testing.T) {
 	require.NoError(t, trace.NewAggregate(err, ctx.Err()))
 }
 
+// TestDefaultPrintUsage verifies that the main `kingpin.Application` parser has not been
+// previously terminated, and that it correctly prints the usage message when using the
+// global `--help` flag or the `help` command, and both are identical.
+func TestDefaultPrintUsage(t *testing.T) {
+	t.Parallel()
+	testExecutable, err := os.Executable()
+	require.NoError(t, err)
+
+	ctx := context.Background()
+
+	cmd := exec.CommandContext(ctx, testExecutable, "version", "--help")
+	cmd.Env = []string{fmt.Sprintf("%s=1", tshBinMainTestEnv), "TELEPORT_TOOLS_VERSION=off"}
+	flagOutput, err := cmd.CombinedOutput()
+	require.NoError(t, err)
+	require.Contains(t, string(flagOutput), "Print the tsh client and Proxy server versions for the current context")
+
+	cmd = exec.CommandContext(ctx, testExecutable, "help", "version")
+	cmd.Env = []string{fmt.Sprintf("%s=1", tshBinMainTestEnv), "TELEPORT_TOOLS_VERSION=off"}
+	commandOutput, err := cmd.CombinedOutput()
+	require.NoError(t, err)
+	require.Equal(t, string(flagOutput), string(commandOutput))
+}
+
 func TestFailedLogin(t *testing.T) {
 	t.Parallel()
 	tmpHomePath := t.TempDir()