BREAKING CHANGE: Remodelled logging setup

- other.ConfigureLoggingFromCliArgs has been renamed to
  other.ConfigureLogging
- The -logfile cli argument has been removed and replaced with an
  argument to other.ConfigureLogging. This argument takes a pointer to a
  string or nil. If it's a valid pointer, it's used just like the
  -logfile cli flag before
- The logfile, if requested via the previously mentioned parameter, can
  now be rotated by calling the returned function. If no logfile is
  specified, the returned function does nothing

logrotate/logrotate.go

@@ -15,13 +15,13 @@ type RotateWriter struct {
 }
 
 // Make a new RotateWriter. Return nil if error occurs during setup.
-func New(filename string) *RotateWriter {
+func New(filename string) (*RotateWriter, error) {
 	w := &RotateWriter{filename: filename}
 	err := w.Rotate()
 	if err != nil {
-		return nil
+		return nil, err
 	}
-	return w
+	return w, nil
 }
 
 // Write satisfies the io.Writer interface.

other/zerolog.go

@@ -8,11 +8,12 @@ import (
 
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
+
+	"git.mstar.dev/mstar/goutils/logrotate"
 )
 
 var cliFlagLogLevel = "info"
 var cliFlagLogJson = false
-var cliFlagLogFile = ""
 
 func SetupFlags() {
 	flag.StringVar(
@@ -27,17 +28,15 @@ func SetupFlags() {
 		false,
 		"Log json objects to stderr instead of nicely formatted ones",
 	)
-	flag.StringVar(
-		&cliFlagLogFile,
-		"logfile",
-		"",
-		"Set the file to write json formatted log messages to",
-	)
 }
 
-func ConfigureLoggingFromCliArgs() {
-	configOutputs()
+// If logfileName != nil, that file will be used for writing logs to.
+// Additionally, this function will then return another function
+// for rotating the log file
+func ConfigureLogging(logfileName *string) func() error {
+	rotateFunc := configOutputs(logfileName)
 	configLevel()
+	return rotateFunc
 }
 
 func configLevel() {
@@ -60,18 +59,16 @@ func configLevel() {
 	log.Info().Str("new-level", cliFlagLogLevel).Msg("New logging level set")
 }
 
-func configOutputs() {
+func configOutputs(logfileName *string) (rotateLogs func() error) {
+	rotateLogs = func() error { return nil }
 	extraLogWriters := []io.Writer{}
-	if cliFlagLogFile != "" {
-		file, err := os.OpenFile(cliFlagLogFile, os.O_APPEND|os.O_CREATE, os.ModeAppend)
+	if logfileName != nil {
+		logfile, err := logrotate.New(*logfileName)
 		if err != nil {
 			log.Fatal().Err(err).Msg("Failed to open log file")
 		}
-		// NOTE: Technically this leaks a file handle
-		// Shouldn't matter though since the log file should be open until the very end
-		// Sooooo, eh. Don't care about adding an elaborate system to close the file at the very end.
-		// OS will do that anyway
-		extraLogWriters = append(extraLogWriters, file)
+		extraLogWriters = append(extraLogWriters, logfile)
+		rotateLogs = logfile.Rotate
 	}
 	if !cliFlagLogJson {
 		console := zerolog.ConsoleWriter{Out: os.Stderr}
@@ -84,4 +81,5 @@ func configOutputs() {
 			append([]io.Writer{log.Logger}, extraLogWriters...)...,
 		)).With().Timestamp().Logger()
 	}
+	return
 }