Go Logger Rotation

This article is about how we rotate log files from within the go app without having to worry about the disk full alerts.

We are going to use https://github.com/lestrrat/go-file-rotatelogs for log rotation.

Example: In the example below we are setting

• MaxAge to 10 seconds. It sets the max-age of a log file before it is purged from the file system. Meaning the file will be deleted after 10 seconds. See

rotatelogs.WithMaxAge(time.Second*10)

• RotationTime is 1 second. It sets the time when the file will be rotated. So the file will be rotated every second. See

rotatelogs.WithRotationTime(time.Second*1)

• Location is /var/log/service/ . See

path := "/var/log/service/"

• Pattern of the file is “old.UTC..2019-11-30.22:40:10” . See

 fmt.Sprintf("%s.%s", path, "%Y-%m-%d.%H:%M:%S")

• Link Path is/var/log/service/current. This file would be a symlink for the actual file. See

rotatelogs.WithLinkName("/var/log/service/current")

Code:

package main

import (
    "fmt"
    "log"
    "time"
    rotatelogs "github.com/lestrrat/go-file-rotatelogs"
    "github.com/sirupsen/logrus"
)

func initiLogger() {
    path := "/var/log/service/old.UTC."
    writer, err := rotatelogs.New(
        fmt.Sprintf("%s.%s", path, "%Y-%m-%d.%H:%M:%S"),
        rotatelogs.WithLinkName("/var/log/service/current"),
        rotatelogs.WithMaxAge(time.Second*10),
        rotatelogs.WithRotationTime(time.Second*1),
    )
    if err != nil {
        log.Fatalf("Failed to Initialize Log File %s", err)
    }
    log.SetOutput(writer)
    return
}

func main() {
    initiLogger()
    for i := 0; i < 100; i++ {
        time.Sleep(time.Second * 1)
        log.Printf("Hello, World!")
    }
    fmt.Scanln()
}

Go to the location /var/log/service/. You will notice

• Files are rotated every second.
• Max age of the file is 10 seconds. So every file will be deleted after 10 seconds.