Simple logger using `zap` and `lumberjack`

logger.go

// Author: Khiem Doan
// Github: https://github.com/khiemdoan
// Email: doankhiem.crazy<at>gmail.com

package logger

import (
	"os"
	"path/filepath"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
)

func NewLogger(logFile string) *zap.SugaredLogger {
	logDir := "logs"
	if fileInfo, err := os.Stat(logDir); os.IsNotExist(err) {
		os.MkdirAll(logDir, 0755)
	} else {
		if !fileInfo.IsDir() {
			os.Remove(logDir)
			os.MkdirAll(logDir, 0755)
		}
	}

	consoleCfg := zap.NewDevelopmentEncoderConfig()
	consoleCfg.EncodeLevel = zapcore.CapitalColorLevelEncoder
	consoleEncoder := zapcore.NewConsoleEncoder(consoleCfg)
	consoleOutput := zapcore.AddSync(os.Stdout)
	consoleLevel := zap.NewAtomicLevelAt(zap.InfoLevel)

	fileCfg := zap.NewProductionEncoderConfig()
	fileCfg.TimeKey = "time"
	fileCfg.EncodeTime = zapcore.ISO8601TimeEncoder
	fileEncoder := zapcore.NewJSONEncoder(fileCfg)
	fileOutput := zapcore.AddSync(&lumberjack.Logger{
		Filename:   filepath.Join(logDir, logFile),
		MaxSize:    10, // megabytes
		MaxBackups: 3,
		MaxAge:     7, // days
	})
	fileLevel := zap.NewAtomicLevelAt(zap.WarnLevel)

	core := zapcore.NewTee(
		zapcore.NewCore(consoleEncoder, consoleOutput, consoleLevel),
		zapcore.NewCore(fileEncoder, fileOutput, fileLevel),
	)
	zapLogger := zap.New(core, zap.AddCaller())
	return zapLogger.Sugar()
}