From c15fae57e125c96e5e8147dc6c9b2eb7ce7c3e6d Mon Sep 17 00:00:00 2001
From: Bruno Carlin <bruno@bcarlin.net>
Date: Wed, 22 Oct 2014 11:32:57 +0200
Subject: [PATCH] Add A syslog backend that writes to the host daemon

---
 backend.go | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 logging.go |  4 +++
 2 files changed, 94 insertions(+)

diff --git a/backend.go b/backend.go
index 39fc205..882357b 100644
--- a/backend.go
+++ b/backend.go
@@ -4,7 +4,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log/syslog"
 	"os"
+	"strings"
 )
 
 type Backend interface {
@@ -80,3 +82,91 @@ func (b *FileBackend) Level() Level {
 func (b *FileBackend) SetFormatter(f *Formatter) {
 	b.formatter = f
 }
+
+//
+// Syslog Backend
+//
+
+type SyslogBackend struct {
+	w         *syslog.Writer
+	formatter *Formatter
+	level     Level
+}
+
+func NewSyslogBackend(facilityName string, tag string) (Backend, error) {
+	f, err := facility(facilityName)
+	if err != nil {
+		return nil, err
+	}
+	w, err := syslog.New(f, tag)
+	if err != nil {
+		return nil, err
+	}
+	sb := &SyslogBackend{
+		w:         w,
+		formatter: &basicFormatter,
+	}
+	return sb, nil
+}
+
+func (sb *SyslogBackend) Write(r *Record) (err error) {
+	text := (*sb.formatter)(r)
+	switch r.Level {
+	case DEBUG:
+		err = sb.w.Debug(text)
+	case INFO:
+		err = sb.w.Info(text)
+	case WARNING:
+		err = sb.w.Warning(text)
+	case ERROR:
+		err = sb.w.Err(text)
+	case CRITICAL:
+		err = sb.w.Crit(text)
+	case FATAL:
+		err = sb.w.Emerg(text)
+	}
+	return err
+}
+
+func (sb *SyslogBackend) SetFormatter(f *Formatter) {
+	sb.formatter = f
+}
+
+func (sb *SyslogBackend) SetLevel(level Level) {
+	sb.level = level
+}
+
+func (sb *SyslogBackend) Level() Level {
+	return sb.level
+}
+
+var facilities = map[string]syslog.Priority{
+	"kern":     syslog.LOG_KERN,
+	"user":     syslog.LOG_USER,
+	"mail":     syslog.LOG_MAIL,
+	"daemon":   syslog.LOG_DAEMON,
+	"auth":     syslog.LOG_AUTH,
+	"syslog":   syslog.LOG_SYSLOG,
+	"lpr":      syslog.LOG_LPR,
+	"news":     syslog.LOG_NEWS,
+	"uucp":     syslog.LOG_UUCP,
+	"cron":     syslog.LOG_CRON,
+	"authpriv": syslog.LOG_AUTHPRIV,
+	"ftp":      syslog.LOG_FTP,
+	"local0":   syslog.LOG_LOCAL0,
+	"local1":   syslog.LOG_LOCAL1,
+	"local2":   syslog.LOG_LOCAL2,
+	"local3":   syslog.LOG_LOCAL3,
+	"local4":   syslog.LOG_LOCAL4,
+	"local5":   syslog.LOG_LOCAL5,
+	"local6":   syslog.LOG_LOCAL6,
+	"local7":   syslog.LOG_LOCAL7,
+}
+
+func facility(name string) (syslog.Priority, error) {
+	if p, ok := facilities[strings.ToLower(name)]; !ok {
+		return 0, fmt.Errorf("Facility '%s' does not exist", name)
+	} else {
+		return p, nil
+	}
+}
diff --git a/logging.go b/logging.go
index 43d7b59..daff311 100644
--- a/logging.go
+++ b/logging.go
@@ -58,6 +58,10 @@ var defaultFormatter Formatter = func(r *Record) string {
 		strings.TrimSpace(r.Message))
 }
 
+var basicFormatter Formatter = func(r *Record) string {
+	return fmt.Sprintf("%s: %s", r.Logger, strings.TrimSpace(r.Message))
+}
+
 func init() {
 	loggers = make(map[string]*Logger, 3)