Add support for logging to syslog.

Author: brocaar

cmd/chirpstack-gateway-bridge/cmd/configfile.go

@@ -12,7 +12,12 @@ import (
 // when updating this template, don't forget to update config.md!
 const configTemplate = `[general]
 # debug=5, info=4, warning=3, error=2, fatal=1, panic=0
-log_level = {{ .General.LogLevel }}
+log_level={{ .General.LogLevel }}
+
+# Log to syslog.
+#
+# When set to true, log messages are being written to syslog.
+log_to_syslog={{ .General.LogToSyslog }}
 
 
 # Filters.

cmd/chirpstack-gateway-bridge/cmd/root_run.go

@@ -1,12 +1,14 @@
 package cmd
 
 import (
+	"log/syslog"
 	"os"
 	"os/signal"
 	"syscall"
 
 	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
+	lsyslog "github.com/sirupsen/logrus/hooks/syslog"
 	"github.com/spf13/cobra"
 
 	"github.com/brocaar/chirpstack-gateway-bridge/internal/backend"
@@ -23,6 +25,7 @@ func run(cmd *cobra.Command, args []string) error {
 
 	tasks := []func() error{
 		setLogLevel,
+		setSyslog,
 		printStartMessage,
 		setupFilters,
 		setupBackend,
@@ -52,6 +55,38 @@ func setLogLevel() error {
 	return nil
 }
 
+func setSyslog() error {
+	if !config.C.General.LogToSyslog {
+		return nil
+	}
+
+	var prio syslog.Priority
+
+	switch log.StandardLogger().Level {
+	case log.DebugLevel:
+		prio = syslog.LOG_USER | syslog.LOG_DEBUG
+	case log.InfoLevel:
+		prio = syslog.LOG_USER | syslog.LOG_INFO
+	case log.WarnLevel:
+		prio = syslog.LOG_USER | syslog.LOG_WARNING
+	case log.ErrorLevel:
+		prio = syslog.LOG_USER | syslog.LOG_ERR
+	case log.FatalLevel:
+		prio = syslog.LOG_USER | syslog.LOG_CRIT
+	case log.PanicLevel:
+		prio = syslog.LOG_USER | syslog.LOG_CRIT
+	}
+
+	hook, err := lsyslog.NewSyslogHook("", "", prio, "chirpstack-gateway-bridge")
+	if err != nil {
+		return errors.Wrap(err, "get syslog hook error")
+	}
+
+	log.AddHook(hook)
+
+	return nil
+}
+
 func printStartMessage() error {
 	log.WithFields(log.Fields{
 		"version": version,

docs/content/install/config.md

@@ -64,7 +64,12 @@ Example configuration file:
 {{<highlight toml>}}
 [general]
 # debug=5, info=4, warning=3, error=2, fatal=1, panic=0
-log_level = 4
+log_level=4
+
+# Log to syslog.
+#
+# When set to true, log messages are being written to syslog.
+log_to_syslog=false
 
 
 # Filters.
@@ -145,10 +150,10 @@ type="semtech_udp"
   crc_check=true
 
   # Event API URL.
-  event_url="ipc:///tmp/concentratord_event"
+  event_url="icp:///tmp/concentratord_event"
 
   # Command API URL.
-  command_url="ipc:///tmp/concentratord_command"
+  command_url="icp:///tmp/concentratord_command"
 
 
   # Basic Station backend.

internal/config/config.go

@@ -7,7 +7,8 @@ import (
 // Config defines the configuration structure.
 type Config struct {
 	General struct {
-		LogLevel int `mapstructure:"log_level"`
+		LogLevel    int  `mapstructure:"log_level"`
+		LogToSyslog bool `mapstructure:"log_to_syslog"`
 	}
 
 	Filters struct {