khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 1 | // Copyright 2018 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | // +build !windows |
| 16 | |
| 17 | package logutil |
| 18 | |
| 19 | import ( |
| 20 | "bytes" |
| 21 | "encoding/json" |
| 22 | "fmt" |
| 23 | "io" |
| 24 | "os" |
| 25 | "path/filepath" |
| 26 | |
| 27 | "github.com/coreos/etcd/pkg/systemd" |
| 28 | |
| 29 | "github.com/coreos/go-systemd/journal" |
| 30 | "go.uber.org/zap/zapcore" |
| 31 | ) |
| 32 | |
| 33 | // NewJournalWriter wraps "io.Writer" to redirect log output |
| 34 | // to the local systemd journal. If journald send fails, it fails |
| 35 | // back to writing to the original writer. |
| 36 | // The decode overhead is only <30µs per write. |
| 37 | // Reference: https://github.com/coreos/pkg/blob/master/capnslog/journald_formatter.go |
| 38 | func NewJournalWriter(wr io.Writer) (io.Writer, error) { |
| 39 | return &journalWriter{Writer: wr}, systemd.DialJournal() |
| 40 | } |
| 41 | |
| 42 | type journalWriter struct { |
| 43 | io.Writer |
| 44 | } |
| 45 | |
| 46 | // WARN: assume that etcd uses default field names in zap encoder config |
| 47 | // make sure to keep this up-to-date! |
| 48 | type logLine struct { |
| 49 | Level string `json:"level"` |
| 50 | Caller string `json:"caller"` |
| 51 | } |
| 52 | |
| 53 | func (w *journalWriter) Write(p []byte) (int, error) { |
| 54 | line := &logLine{} |
| 55 | if err := json.NewDecoder(bytes.NewReader(p)).Decode(line); err != nil { |
| 56 | return 0, err |
| 57 | } |
| 58 | |
| 59 | var pri journal.Priority |
| 60 | switch line.Level { |
| 61 | case zapcore.DebugLevel.String(): |
| 62 | pri = journal.PriDebug |
| 63 | case zapcore.InfoLevel.String(): |
| 64 | pri = journal.PriInfo |
| 65 | |
| 66 | case zapcore.WarnLevel.String(): |
| 67 | pri = journal.PriWarning |
| 68 | case zapcore.ErrorLevel.String(): |
| 69 | pri = journal.PriErr |
| 70 | |
| 71 | case zapcore.DPanicLevel.String(): |
| 72 | pri = journal.PriCrit |
| 73 | case zapcore.PanicLevel.String(): |
| 74 | pri = journal.PriCrit |
| 75 | case zapcore.FatalLevel.String(): |
| 76 | pri = journal.PriCrit |
| 77 | |
| 78 | default: |
| 79 | panic(fmt.Errorf("unknown log level: %q", line.Level)) |
| 80 | } |
| 81 | |
| 82 | err := journal.Send(string(p), pri, map[string]string{ |
| 83 | "PACKAGE": filepath.Dir(line.Caller), |
| 84 | "SYSLOG_IDENTIFIER": filepath.Base(os.Args[0]), |
| 85 | }) |
| 86 | if err != nil { |
| 87 | // "journal" also falls back to stderr |
| 88 | // "fmt.Fprintln(os.Stderr, s)" |
| 89 | return w.Writer.Write(p) |
| 90 | } |
| 91 | return 0, nil |
| 92 | } |