blob: b1788bc83f8cb277b460216d27a0f5835e09ff5f [file] [log] [blame]
// Copyright 2018 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !windows
package logutil
import (
"bytes"
"encoding/json"
"fmt"
"io"
"os"
"path/filepath"
"github.com/coreos/etcd/pkg/systemd"
"github.com/coreos/go-systemd/journal"
"go.uber.org/zap/zapcore"
)
// NewJournalWriter wraps "io.Writer" to redirect log output
// to the local systemd journal. If journald send fails, it fails
// back to writing to the original writer.
// The decode overhead is only <30┬Ás per write.
// Reference: https://github.com/coreos/pkg/blob/master/capnslog/journald_formatter.go
func NewJournalWriter(wr io.Writer) (io.Writer, error) {
return &journalWriter{Writer: wr}, systemd.DialJournal()
}
type journalWriter struct {
io.Writer
}
// WARN: assume that etcd uses default field names in zap encoder config
// make sure to keep this up-to-date!
type logLine struct {
Level string `json:"level"`
Caller string `json:"caller"`
}
func (w *journalWriter) Write(p []byte) (int, error) {
line := &logLine{}
if err := json.NewDecoder(bytes.NewReader(p)).Decode(line); err != nil {
return 0, err
}
var pri journal.Priority
switch line.Level {
case zapcore.DebugLevel.String():
pri = journal.PriDebug
case zapcore.InfoLevel.String():
pri = journal.PriInfo
case zapcore.WarnLevel.String():
pri = journal.PriWarning
case zapcore.ErrorLevel.String():
pri = journal.PriErr
case zapcore.DPanicLevel.String():
pri = journal.PriCrit
case zapcore.PanicLevel.String():
pri = journal.PriCrit
case zapcore.FatalLevel.String():
pri = journal.PriCrit
default:
panic(fmt.Errorf("unknown log level: %q", line.Level))
}
err := journal.Send(string(p), pri, map[string]string{
"PACKAGE": filepath.Dir(line.Caller),
"SYSLOG_IDENTIFIER": filepath.Base(os.Args[0]),
})
if err != nil {
// "journal" also falls back to stderr
// "fmt.Fprintln(os.Stderr, s)"
return w.Writer.Write(p)
}
return 0, nil
}