1// Copyright 2015 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14// +build !windows,!nacl,!plan9
15
16package log
17
18import (
19	"fmt"
20	"log/syslog"
21	"os"
22
23	"github.com/sirupsen/logrus"
24)
25
26var _ logrus.Formatter = (*syslogger)(nil)
27
28func init() {
29	setSyslogFormatter = func(l logger, appname, local string) error {
30		if appname == "" {
31			return fmt.Errorf("missing appname parameter")
32		}
33		if local == "" {
34			return fmt.Errorf("missing local parameter")
35		}
36
37		fmter, err := newSyslogger(appname, local, l.entry.Logger.Formatter)
38		if err != nil {
39			fmt.Fprintf(os.Stderr, "error creating syslog formatter: %v\n", err)
40			l.entry.Errorf("can't connect logger to syslog: %v", err)
41			return err
42		}
43		l.entry.Logger.Formatter = fmter
44		return nil
45	}
46}
47
48var prefixTag []byte
49
50type syslogger struct {
51	wrap logrus.Formatter
52	out  *syslog.Writer
53}
54
55func newSyslogger(appname string, facility string, fmter logrus.Formatter) (*syslogger, error) {
56	priority, err := getFacility(facility)
57	if err != nil {
58		return nil, err
59	}
60	out, err := syslog.New(priority, appname)
61	_, isJSON := fmter.(*logrus.JSONFormatter)
62	if isJSON {
63		// add cee tag to json formatted syslogs
64		prefixTag = []byte("@cee:")
65	}
66	return &syslogger{
67		out:  out,
68		wrap: fmter,
69	}, err
70}
71
72func getFacility(facility string) (syslog.Priority, error) {
73	switch facility {
74	case "0":
75		return syslog.LOG_LOCAL0, nil
76	case "1":
77		return syslog.LOG_LOCAL1, nil
78	case "2":
79		return syslog.LOG_LOCAL2, nil
80	case "3":
81		return syslog.LOG_LOCAL3, nil
82	case "4":
83		return syslog.LOG_LOCAL4, nil
84	case "5":
85		return syslog.LOG_LOCAL5, nil
86	case "6":
87		return syslog.LOG_LOCAL6, nil
88	case "7":
89		return syslog.LOG_LOCAL7, nil
90	}
91	return syslog.LOG_LOCAL0, fmt.Errorf("invalid local(%s) for syslog", facility)
92}
93
94func (s *syslogger) Format(e *logrus.Entry) ([]byte, error) {
95	data, err := s.wrap.Format(e)
96	if err != nil {
97		fmt.Fprintf(os.Stderr, "syslogger: can't format entry: %v\n", err)
98		return data, err
99	}
100	// only append tag to data sent to syslog (line), not to what
101	// is returned
102	line := string(append(prefixTag, data...))
103
104	switch e.Level {
105	case logrus.PanicLevel:
106		err = s.out.Crit(line)
107	case logrus.FatalLevel:
108		err = s.out.Crit(line)
109	case logrus.ErrorLevel:
110		err = s.out.Err(line)
111	case logrus.WarnLevel:
112		err = s.out.Warning(line)
113	case logrus.InfoLevel:
114		err = s.out.Info(line)
115	case logrus.DebugLevel:
116		err = s.out.Debug(line)
117	default:
118		err = s.out.Notice(line)
119	}
120
121	if err != nil {
122		fmt.Fprintf(os.Stderr, "syslogger: can't send log to syslog: %v\n", err)
123	}
124
125	return data, err
126}
127