derkan / nlog

Structured Go Logger without external dependencies

nlog logger

nlog is a GoLang library for performant logging.

• Easy config, easy API
• Support multiple formatters
  • Console formatter(colored)
  • JSON formatter
• Different io.Writer stream wrappers
  • Simultaneous logging to multiple writes(via channels) concurrently
  • Async logging to multiple writes(via channels) concurrently
    • Writes multiple writers in parellel with buffered channel
• Includes syslog writer(wrapped around standard syslog for correct logging levels)
• Contextual logging
  • Allows data to be added to log messages in the form of key:value pairs
• Structured logging
  • Logs with levels
• Minimal memory allocs
• No dependencies
• Hook support
• But you can bring your own json encoder for serializing objects and define it for a formatter
• No reflection for high performance
• Includes file rotater log writer with compress support
• Has a loader from yaml formatted config file
• Sub logger support

Logging concept

• Writer is after formatter, so for nlog will not build format message for each writer. It will build format only once and use it in all writers assigned to it.
• You can assign logging level for your formatter. If user log level is too detail, formatter will not format message and will not log it.
• nlog Internally uses buffer pool for low allocation.

Benchmarks

Some benchmark data

goos: linux
goarch: amd64
pkg: github.com/derkan/nlog/log
BenchmarkInfof-4         2206740               538 ns/op             123 B/op          1 allocs/op
BenchmarkStr-4           1505314               803 ns/op             216 B/op          1 allocs/op
BenchmarkWith-4          1453686               798 ns/op             223 B/op          1 allocs/op

Quick start

package main

import "github.com/derkan/nlog/log"

func main(){
    log.Infof("test: %d", 123)
    log.Info().Str("a", "string").Msg(`str "key" test`)
}

And you'll get logs on console:

2020/07/14 22:04:24 INFO test: 123
2020/07/14 22:04:24 INFO str "key" test a=string

If you want color init logger with your options:

package main

import (
    "github.com/derkan/nlog/log"
    "github.com/derkan/nlog/log/formatter/console"
)

func main() {
    log.Init(
        log.WithFormatter(
            console.NewFormatter(
                console.WithColor(),
                console.WithDate(),
                console.WithTime(),
            )),
    )
    log.Infof("test: %d", 123)
    log.Debug().Str("a", "string").Msg("my debug")
    log.Warn().Int("i", 4).Msg("my warning")
    log.Info().Bool("b", true).Strs("strslice", []string{"a"}).Msg("my bool")
    log.Error().Err(nil).With("k", map[string]int{"x": 1}).Msg("my err with map")
}

You'll get colored output:

Installation

go get -u github.com/derkan/nlog

Formatters

Formatters are used to format log message according to your needs.

Console Formatter

Console formatter is used to print plain logs to given io.WriteCloser.

Option	Default	Description
WithColor	false	When enabled, prints colored logs
WithWriter	os.Stdout	Where to log messages

TODO

• Documentation
• Tests
• Bechmarks