A simple logging module for go, with a rotating file feature and console logging.

Installation

go get github.com/TranDuyThanh/mlog

Level logging

mlog.Trace("Hello World !")
mlog.Info("Hello World !")
mlog.Warning("Hello World !")
mlog.Error("Hello World !")
mlog.Fatal("Hello World !")

You can set the logging level on a Logger, then it will only log entries with that severity or anything above it:

mlog.Start(mlog.LevelTrace,   "app.log")
mlog.Start(mlog.LevelInfo,    "app.log")
mlog.Start(mlog.LevelWarning, "app.log")
mlog.Start(mlog.LevelError,   "app.log")

Rotation

Log rotation is provided with mlog. Default max size of log file is: 1GB

Note:

Log rotation should be done by an external program (like logrotate(8)) that can compress and delete old log entries

Example

Write to stdout/stderr and create a rotating logfile

package main

import (
	"github.com/TranDuyThanh/mlog"
)

func main() {
	mlog.Start(mlog.LevelInfo, "app.log")

	mlog.Info("Hello World !")

	ipsum := "ipsum"
	mlog.Warning("Lorem %s", ipsum)
}

Write to stdout/stderr only

package main

import (
	"github.com/TranDuyThanh/mlog"
)

func main() {
	mlog.Start(mlog.LevelInfo, "")

	mlog.Info("Hello World !")

	ipsum := "ipsum"
	mlog.Warning("Lorem %s", ipsum)
}

By default, the log will be rolled over to a backup file when its size reaches 10Mb and 10 such files will be created (and eventually reused).

Alternatively, you can specify the max size of the log file before it gets rotated, and the number of backup files you want to create, with the StartEx function.

package main

import "github.com/TranDuyThanh/mlog"

func main() {
    mlog.StartEx(mlog.LevelInfo, "app.log", 5*1024*1024, 5)

    mlog.Info("Hello World !")

    ipsum := "ipsum"
    mlog.Warning("Lorem %s", ipsum)
}

This will rotate the file when it reaches 5Mb and 5 backup files will eventually be created.

Setting logger flags:

mlog.DefaultFlags = log.Ldate|log.Ltime|log.Lmicroseconds|log.Lshortfile

Output

I: 2015/05/15 07:09:45 main.go:10: Hello World !
W: 2015/05/15 07:09:45 main.go:13: Lorem ipsum