High Level Logger

HlLogger is an opinionated logger on top of the Golang standard library logger. It adds:

syslog inspired logging facilities such as:
- Debug
- Info
- Notice
- Warning
- Error
- Critical
- Alert
- Emergency
automatic systemd-journald integration if systemd is detected as executor and output is os.Stdout or os.Stderr
automatic AWS CloudWatch Logs integration if AWS Lambda execution environment is detected

Installation

go get github.com/hekmon/hllogger/v2

Usage

package main

import (
	"os"

	"github.com/hekmon/hllogger/v2"
)

func main() {
	logger := hllogger.New(os.Stdout, hllogger.Debug)
	logger.Debug("test")
	logger.Info("test")
	logger.Notice("test")
	logger.Warning("test")
	logger.Error("test")
	logger.Critical("test")
	logger.Alert("test")
	logger.Emergency("test")
}

If you init the logger with the hllogger.Info level, all calls to logger.Debug() will no-op (won't print anything). If you init the logger with the hllogger.Notice level, all calls to to logger.Debug() and logger.Info() will no-op (won't print anything). And so on...

Regular output

Regular (default) ouput on your terminal or on a file.

2022/02/14 20:37:31     DEBUG: test
2022/02/14 20:37:31      INFO: test
2022/02/14 20:37:31    NOTICE: test
2022/02/14 20:37:31   WARNING: test
2022/02/14 20:37:31     ERROR: test
2022/02/14 20:37:31  CRITICAL: test
2022/02/14 20:37:31     ALERT: test
2022/02/14 20:37:31 EMERGENCY: test

systemd-journald integration

Automatically enabled if started by systemd and output is os.Stdout or os.Stderr. By integrating with systemd-journald, the lib will indicate the log level of each log to journald. It will allows log manipulation directly with journald (printing only info level while debug have been printed) but also log level highlighting (colors).

log level highlighting

emergency broadcast

hekmon@testserver1:~$ sudo systemctl start logleveltest.service

Broadcast message from systemd-journald@testserver1 (Mon 2022-02-14 20:47:52 UTC):

hlloggertest[1031126]: EMERGENCY: test

hekmon@testserver1:~$

AWS Lambda integration

If a AWS lambda execution environment is detected and therefor logs are being handled by AWS Cloudwatch logs, the logger won't use any time based flags as CloudWatch Logs will be taking care of it. Only log level and actual log message will be output:

    DEBUG: test
     INFO: test
   NOTICE: test
  WARNING: test
    ERROR: test
 CRITICAL: test
    ALERT: test
EMERGENCY: test