cmd/maddy: Allow to set logging target from command line

Useful to redirect log messages generated before config is parsed.

cmd/maddy/main.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"strings"
 
 	"github.com/foxcpp/maddy"
 	"github.com/foxcpp/maddy/config"
@@ -16,6 +17,8 @@ import (
 func main() {
 	configPath := flag.String("config", filepath.Join(ConfigDirectory, "maddy.conf"), "path to configuration file")
 
+	logTargets := flag.String("log", "stderr", "default logging target(s)")
+
 	flag.StringVar(&config.StateDirectory, "state", DefaultStateDirectory, "path to the state directory")
 	flag.StringVar(&config.LibexecDirectory, "libexec", DefaultLibexecDirectory, "path to the libexec directory")
 	flag.StringVar(&config.RuntimeDirectory, "runtime", DefaultRuntimeDirectory, "path to the runtime directory")
@@ -27,6 +30,13 @@ func main() {
 
 	flag.Parse()
 
+	var err error
+	log.DefaultLogger.Out, err = maddy.LogOutputOption(strings.Split(*logTargets, " "))
+	if err != nil {
+		log.Println(err)
+		os.Exit(2)
+	}
+
 	if err := ensureDirectoryWritable(config.StateDirectory); err != nil {
 		log.Println(err)
 		os.Exit(2)

config.go

@@ -21,8 +21,12 @@ func logOutput(m *config.Map, node *config.Node) (interface{}, error) {
 		return nil, m.MatchErr("can't declare block here")
 	}
 
-	outs := make([]log.FuncLog, 0, len(node.Args))
+	return LogOutputOption(node.Args)
-	for _, arg := range node.Args {
+}
+
+func LogOutputOption(args []string) (log.FuncLog, error) {
+	outs := make([]log.FuncLog, 0, len(args))
+	for _, arg := range args {
 		switch arg {
 		case "stderr":
 			outs = append(outs, log.WriterLog(os.Stderr, false))
@@ -35,7 +39,7 @@ func logOutput(m *config.Map, node *config.Node) (interface{}, error) {
 			}
 			outs = append(outs, syslogOut)
 		case "off":
-			if len(node.Args) != 1 {
+			if len(args) != 1 {
 				return nil, errors.New("'off' can't be combined with other log targets")
 			}
 			return nil, nil
@@ -56,5 +60,5 @@ func logOutput(m *config.Map, node *config.Node) (interface{}, error) {
 }
 
 func defaultLogOutput() (interface{}, error) {
-	return log.WriterLog(os.Stderr, false), nil
+	return log.DefaultLogger.Out, nil
 }

maddy.1.scd

@@ -32,7 +32,10 @@ IMAP server functionality in one application.
 *-runtime* _path_
 	Path to the runtime directory. Temporary data will be stored here.
 	It is not recommended to use tmpfs for it since runtime directory is used only 
-	for large objects that can't be stored in RAM directly. 
+	for large objects that can't be stored in RAM directly.
+
+*-log* _targets..._
+	Logging targets. Format is the same as 'log' config directive. 
 
 *-debug*
 	Enable debug log. You want to use it when reporting bugs.