fix(cli): return non-zero exit status on command errors (#4888)

cmd/server/main.go

@@ -189,6 +189,7 @@ func main() {
 
 	if err := cmd.Run(context.Background(), os.Args); err != nil {
 		fmt.Println(err)
+		os.Exit(1)
 	}
 }
 

cmd/server/main_test.go

@@ -16,11 +16,80 @@ package main
 
 import (
 	"os"
+	"os/exec"
+	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/require"
+
+	"github.com/livekit/livekit-server/version"
 )
 
+func TestMain(m *testing.M) {
+	if os.Getenv("LIVEKIT_TEST_RUN_MAIN") == "1" {
+		main()
+		os.Exit(0)
+	}
+	os.Exit(m.Run())
+}
+
+func TestMainExitCode(t *testing.T) {
+	testBinary, err := os.Executable()
+	require.NoError(t, err)
+	missingConfig := filepath.Join(t.TempDir(), "missing.yaml")
+
+	for _, tt := range []struct {
+		name     string
+		args     []string
+		exitCode int
+		output   string
+	}{
+		{
+			name:     "missing config",
+			args:     []string{"--config", missingConfig, "ports"},
+			exitCode: 1,
+			output:   missingConfig,
+		},
+		{
+			name:     "unknown flag",
+			args:     []string{"--unknown-flag"},
+			exitCode: 1,
+			output:   "flag provided but not defined",
+		},
+		{
+			name:     "invalid flag value",
+			args:     []string{"--dev=invalid"},
+			exitCode: 1,
+			output:   "invalid value",
+		},
+		{
+			name:   "help",
+			args:   []string{"--help"},
+			output: "High performance WebRTC server",
+		},
+		{
+			name:   "version",
+			args:   []string{"--version"},
+			output: version.Version,
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			cmd := exec.CommandContext(t.Context(), testBinary, tt.args...)
+			// Run the real entry point without inheriting server configuration.
+			cmd.Env = []string{"LIVEKIT_TEST_RUN_MAIN=1"}
+			output, err := cmd.CombinedOutput()
+			if tt.exitCode == 0 {
+				require.NoError(t, err, string(output))
+			} else {
+				var exitErr *exec.ExitError
+				require.ErrorAs(t, err, &exitErr, string(output))
+				require.Equal(t, tt.exitCode, exitErr.ExitCode(), string(output))
+			}
+			require.Contains(t, string(output), tt.output)
+		})
+	}
+}
+
 type testStruct struct {
 	configFileName string
 	configBody     string