fix: Fallback to file log on demonize if no syslog

Author: efirs

core/cfg/logger.go

@@ -23,7 +23,7 @@ import (
 	"github.com/tigrisdata/tigrisfs/log"
 )
 
-func InitLoggers(flags *FlagStorage) {
+func InitLoggers(flags *FlagStorage) error {
 	lf := flags.LogFile
 	if lf == "" {
 		lf = "stderr"
@@ -32,7 +32,10 @@ func InitLoggers(flags *FlagStorage) {
 		}
 	}
 
-	log.InitLoggerRedirect(lf)
+	err := log.InitLoggerRedirect(lf, len(flags.LogFile) == 0)
+	if err != nil {
+		return err
+	}
 
 	log.DefaultLogConfig = &log.LogConfig{
 		Level:  flags.LogLevel,
@@ -51,4 +54,6 @@ func InitLoggers(flags *FlagStorage) {
 	log.SetLoggersConfig(log.DefaultLogConfig)
 
 	//	log.DumpLoggers("InitLoggers")
+
+	return nil
 }

log/dup_default.go

@@ -18,10 +18,11 @@
 package log
 
 import (
-	"golang.org/x/sys/unix"
 	"io"
 	"log/syslog"
 	"os"
+
+	"golang.org/x/sys/unix"
 )
 
 func redirectStdout(target *os.File) error {
@@ -32,10 +33,6 @@ func redirectStderr(target *os.File) error {
 	return unix.Dup2(int(target.Fd()), int(os.Stderr.Fd()))
 }
 
-func InitSyslog() io.Writer {
-	lf, err := syslog.New(syslog.LOG_INFO, "tigrisfs")
-	if err != nil {
-		Fatal().Err(err).Msg("Failed to connect to syslog")
-	}
-	return lf
+func InitSyslog() (io.Writer, error) {
+	return syslog.New(syslog.LOG_INFO, "tigrisfs")
 }

log/dup_windows.go

@@ -38,6 +38,6 @@ func redirectStderr(target *os.File) error {
 	return err
 }
 
-func InitSyslog() io.Writer {
-	return logWriter
+func InitSyslog() (io.Writer, error) {
+	return logWriter, nil
 }

log/log.go

@@ -22,6 +22,10 @@ func Error() *zerolog.Event {
 	return defaultLog.Error()
 }
 
+func Warn() *zerolog.Event {
+	return defaultLog.Warn()
+}
+
 func Info() *zerolog.Event {
 	return defaultLog.Info()
 }

log/logger.go

@@ -42,30 +42,42 @@ var (
 
 var logWriter io.Writer = os.Stderr
 
-func logStderr(msg string, args ...any) {
-	_, _ = fmt.Fprintf(os.Stderr, msg, args...)
-}
+func InitLoggerRedirect(logFileName string, defLog bool) error {
+	if logFileName == "stderr" || logFileName == "/dev/stderr" || logFileName == "" {
+		return nil
+	}
 
-func InitLoggerRedirect(logFileName string) {
 	if logFileName == "syslog" {
-		logWriter = InitSyslog()
-	} else if logFileName != "stderr" && logFileName != "/dev/stderr" && logFileName != "" {
 		var err error
-		lf, err := os.OpenFile(logFileName, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o666)
-		if err != nil {
-			logStderr("Couldn't open file %v for writing logs", logFileName)
-			return
-		}
-		if err = redirectStdout(lf); err != nil {
-			logStderr("Couldn't redirect STDOUT to the log file %v", logFileName)
-			return
+		logWriter, err = InitSyslog()
+		if err == nil {
+			return nil
 		}
-		if err = redirectStderr(lf); err != nil {
-			logStderr("Couldn't redirect STDERR to the log file %v", logFileName)
-			return
+
+		if !defLog {
+			return err
 		}
-		logWriter = lf
+
+		// log file is not set and we are deamonizing redirect to default file location
+		Warn().Err(err).Msg("failed to open syslog. redirecting logs to /var/log/tigrisfs.log")
+		logFileName = "/var/log/tigrisfs.log"
+	}
+
+	var err error
+	lf, err := os.OpenFile(logFileName, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0o666)
+	if err != nil {
+		return fmt.Errorf("couldn't open file %v for writing logs: %w", logFileName, err)
+	}
+	if err = redirectStdout(lf); err != nil {
+		return fmt.Errorf("couldn't redirect STDOUT to the log file %v: %w", logFileName, err)
 	}
+	if err = redirectStderr(lf); err != nil {
+		return fmt.Errorf("couldn't redirect STDERR to the log file %v: %w", logFileName, err)
+	}
+
+	logWriter = lf
+
+	return nil
 }
 
 func SetCloudLogLevel(level zerolog.Level) {

main.go

@@ -27,6 +27,7 @@ import (
 
 	"github.com/tigrisdata/tigrisfs/core"
 	"github.com/tigrisdata/tigrisfs/core/cfg"
+	"github.com/tigrisdata/tigrisfs/lib"
 	"github.com/tigrisdata/tigrisfs/log"
 	"github.com/urfave/cli"
 
@@ -112,7 +113,13 @@ func main() {
 			}
 		}
 
-		cfg.InitLoggers(flags)
+		err = cfg.InitLoggers(flags)
+		if err != nil {
+			if !flags.Foreground {
+				daemonizer.NotifySuccess(false)
+			}
+			mainLog.Fatal().Err(err).Msg("Unable to initialize logger")
+		}
 
 		mainLog.Debug().Interface("flags", flags).Msg("config")
 
@@ -143,12 +150,20 @@ func main() {
 		if err != nil {
 			if !flags.Foreground {
 				daemonizer.NotifySuccess(false)
+				// if demonized but started from terminal show error to the user
+				if lib.IsTTY(os.Stderr) {
+					_, _ = fmt.Fprintf(os.Stderr, "Mounting file system failed: %v\n", err)
+				}
 			}
 			mainLog.Fatal().Err(err).Msg("Mounting file system failed")
 			// fatal also terminates itself
 		} else {
 			mainLog.Info().Msg("File system has been successfully mounted.")
 			if !flags.Foreground {
+				// if demonized but started from terminal show success to the user
+				if lib.IsTTY(os.Stderr) {
+					_, _ = fmt.Fprintf(os.Stderr, "File system has been successfully mounted\n")
+				}
 				daemonizer.NotifySuccess(true)
 				mainLog.Debug().Msg("Process is daemonized. Closing stdout and stderr.")
 				mainLog.E(os.Stderr.Close())