yackrru / gogger

A Go library for logging.

gogger

A Go library for logging.

Overview

gogger is a logging library, providing just one Log struct and Logger interface. This is to simplify instance creation and to ensure that the exact same approach can always be taken.
Log struct is designed to be highly extensible, using the LogWriter interface for log output and the LogFormatter interface for log formatting, which can be freely replaced. Also, multiple LogWriters can be configured for Log, so that the same log can be written to both stdout and a file, for example.
Since LogWriter and LogFormatter are exported interfaces, users are free to define and use them if they are dissatisfied with the built-in ones. If they are useful, please give us pull request.

Quickstart

Here is an example of using the built-in LogStreamWriter and LogSimpleFormatter. Those details are described after this section.
Remember that Log generation is done here by passing only LogConfig to its constructor, NewLog. Then, configure LogWriter and LogFormatter in LogConfig.

package main

import (
	"github.com/yackrru/gogger"
	"os"
	"time"
)

func main() {
	writer := gogger.NewLogStreamWriter(gogger.LogStreamWriterOption{
		Output: os.Stderr,
	})
	writer.Open()
	defer writer.Close()
	
	logger := gogger.NewLog(&gogger.LogConfig{
		Writers: []gogger.LogWriter{writer},
		Formatter: gogger.NewLogSimpleFormatter(gogger.DefaultLogSimpleFormatterTmpl),
	})
	
	// logging
	logger.Info("log string")
}

LogConfig

It is a centralized setting for Log.

option	default	description
Writers	-	Set a LogWriter for each output destination.
Formatter	-	Only one LogFormatter can be set.
TimeFormat	"2006-01-02 15:04:05.000"	Time stamp format. Specify a time format string for the golang.
LogMinLevel	INFO	Specify the log level you want to output. Log levels are ERROR, WARN, INFO, DEBUG, and OFF.

Writer

LogStreamWriter

It is an asynchronous log writer with an internal buffer of log strings and a log output goroutine.

gogger.NewLogStreamWriter(gogger.LogStreamWriterOption{
	Output: os.Stderr,
	SyncIntervalMills: 100,
})

option	default	description
Output	os.Stderr	Specify the *os.File to which the logs will be output.
SyncIntervalMills	100	The log output interval. (milliseconds)

Formatter

LogSimpleFormatter

It is a LogFormatter that formats a predefined parameter and log string in a format set as a template. The struct itself has only one parameter, a template string called tmpl, which is passed to the constructor when the instance is created.

gogger.NewLogSimpleFormatter(gogger.DefaultLogSimpleFormatterTmpl)

option	default	description
tmpl	"%timestamp% %level% --- [%pkg%] %args%"	The template string. Each parameter is enclosed in %. %args% is the string passed to Log.