Gochill

Golang library for building logging data structure.

Abstract

Logging data structure that supported is following GELF. All data structure should be in json mode. Required fields :

• version
• host
• service
• short_message
• timestamp
• level

We need a library that support this logging data structure but also should be easy to use for other programmers.

Rationale

This library should be only for building logging data structure and print it using stdout or stderr.

Environment Variable

This library will listen to environment variable with registered key SERVICE_NAME. This variable used to fill service json field.

If environment variable not exists, then service will be an empty string.

Log output format have 2 type JSON and TEXT, if use TEXT it will use library Logrus for output. this can be set to environment variable with registered key JSON_FORMAT, this boolean value. if set false it will use TEXT if true output will set to JSON format. default value always set to true

Hostname

This library will automatically load hostname from os using golang's native library

os.Hostname()

But if there is some error, then hostname will be an empty string.

Usage

import "gochill"

gochill.Alert(Msg("alert message"))

Available levels :

• Alert
• Critical
• Error
• Warning
• Notice
• Info
• Debug

Gochill designed with io.MultiWriter it means you can add your own custom io.Writer to proceed your log.

package main

import "gochill"

type CustomWriter struct{}
func (cw CustomWriter) Write(message []byte) (int, error) {
  fmt.Println("hello world")
}

gochill.CustomOutput = CustomWriter{}
gochill.Info(Msg("log info"))

These code should produce an output will send a structured json code and also print "hello world" to stdout.

Each of log function also support for optional fields, usages :

package main

import "gochill"

gochill.Alert(Msg("log alert"), O("key1", "value1"), O("key2", 230))

It will produce result like this :

{"_key1":"value1","_key2":230,"host":"your.hostname","level":1,"service":"","short_message":"log alert","timestamp":1472879389234,"version":1}

If you need a full_message to describe your log, you can filled optional full message like this :

package main

import "gochill"

gochill.Alert(Msg("short message", "full_message"))

Unit Test

How to run :

go test -cover

Via Makefile :

make test