logger

type LogConfig struct {
	// will set the log level to DEBUG
	Debug bool
	//will set the log level to ERROR
	Quiet bool
	//stderr, stdout, file or eventlog (Windows only)
	LogTarget string
	// will direct the logging output to a file. Empty string is
	// interpreted as stderr. If there is an error opening the file the
	// logger will fallback to stderr
	Logfile string
	// will rotate when current file at the specified time interval
	RotationInterval internal.Duration
	// will rotate when current file size exceeds this parameter.
	RotationMaxSize internal.Size
	// maximum rotated files to keep (older ones will be deleted)
	RotationMaxArchives int
}

type LoggerCreator interface {
	CreateLogger(config LogConfig) (io.Writer, error)
}