• 使用logrus配合file-rotatelogs、lfshook实现：
  1 日志文件按时间切割
  2 根据日志等级输出到不同文件
  3 增加默认的日志信息(比如本文中的本机ip，获取本机ip的代码就不贴了)

const (
    _infoPath = "info.log"
    _errorPath = "error.log"
    _rotationHour = 24
    _maxAgeHour = 72
    _timeStampFormat = "2016-01-02 15:04:05"
)
var _logEntry *logrus.Entry
func init() {
    log := logrus.StandardLogger()
    _logEntry = log.WithField("localIp", utils.GetLocalIp())
    log.SetFormatter(&logrus.TextFormatter{
        DisableColors:   true,
        TimestampFormat: _timeStampFormat,
    })
    // 不向控制台打印
    //log.Out = ioutil.Discard
    // 写文件不加锁，具体参考logrus文档确认可不可以不锁
    // log.SetNoLock()
    infoWriter, err := rotatelogs.New(
        _infoPath+".%Y-%m-%d",
        rotatelogs.WithLinkName(_infoPath),
        rotatelogs.WithRotationTime(time.Hour*_rotationHour),
        rotatelogs.WithMaxAge(time.Hour*_maxAgeHour),
    )
    if err != nil {
        panic(err)
    }
    errorWriter, err := rotatelogs.New(
        _errorPath+".%Y-%m-%d",
        rotatelogs.WithLinkName(_errorPath),
        rotatelogs.WithRotationTime(time.Hour*_rotationHour),
        rotatelogs.WithMaxAge(time.Hour*_maxAgeHour),
    )
    if err != nil {
        panic(err)
    }
    allWriter := io.MultiWriter(infoWriter, errorWriter)
    log.AddHook(lfshook.NewHook(
        lfshook.WriterMap{
            logrus.InfoLevel:  infoWriter,
            logrus.ErrorLevel: allWriter,
            logrus.PanicLevel: allWriter,
        },
        &logrus.TextFormatter{
            DisableColors:   true,
            TimestampFormat: _timeStampFormat,
        },
    ))
}

func WithField(key string, value interface{}) *logrus.Entry {
    return _logEntry.WithField(key, value)
}

func Info(args ...interface{}) {
    _logEntry.Info(args...)
}

func Infof(format string, args ...interface{}) {
    _logEntry.Infof(format, args...)
}

func Error(args ...interface{}) {
    _logEntry.Error(args...)
}

func Errorf(format string, args ...interface{}) {
    _logEntry.Errorf(format, args...)
}

func Panic(args ...interface{}) {
    _logEntry.Panic(args...)
}

func Panicf(format string, args ...interface{}) {
    _logEntry.Panicf(format, args...)
}