logger

type Config struct {
	// Level is the minimum enabled logging level
	Level string `yaml:"level" env:"LEVEL" env-default:"INFO"`

	// Logger line ending. Default: "\n" for the all modes except production
	LineEnding string `yaml:"line_ending"`

	// Encoding sets the logger's encoding. InitDefault values are "json" and
	// "console", as well as any third-party encodings registered via
	// RegisterEncoder.
	Encoding string `yaml:"encoding"`

	// Output is a list of URLs or file paths to write logging output to.
	// See Open for details.
	Output []string `yaml:"output"`

	// ErrorOutput is a list of URLs to write internal logger errors to.
	// The default is standard error.
	//
	// Note that this setting only affects internal errors; for sample code that
	// sends error-level logs to a different location from info- and debug-level
	// logs, see the package-level AdvancedConfiguration example.
	ErrorOutput []string `yaml:"error_output"`

	// File logger options
	FileLogger *FileLoggerConfig `yaml:"file_logger_options"`
}

type FileLoggerConfig struct {
	// Filename is the file to write logs to.  Backup log files will be retained
	// in the same directory.  It uses <processname>-lumberjack.log in
	// os.TempDir() if empty.
	LogOutput string `yaml:"log_output"`

	// MaxSize is the maximum size in megabytes of the log file before it gets
	// rotated. It defaults to 100 megabytes.
	MaxSize int `yaml:"max_size"`

	// MaxAge is the maximum number of days to retain old log files based on the
	// timestamp encoded in their filename.  Note that a day is defined as 24
	// hours and may not exactly correspond to calendar days due to daylight
	// savings, leap seconds, etc. The default is not to remove old log files
	// based on age.
	MaxAge int `yaml:"max_age"`

	// MaxBackups is the maximum number of old log files to retain.  The default
	// is to retain all old log files (though MaxAge may still cause them to get
	// deleted.)
	MaxBackups int `yaml:"max_backups"`

	// Compress determines if the rotated log files should be compressed
	// using gzip. The default is not to perform compression.
	Compress bool `yaml:"compress"`
}