log using uber zap and lumberjack

logger.go

// NOTE
// This gist was created long time ago.
// According to zap's doc, now we can use zapcore.AddSync to directly add lumberjack as a zap sync
// see https://github.com/uber-go/zap/blob/master/FAQ.md#does-zap-support-log-rotation
// So I wrote a new gist if anyone is interested:
// https://gist.github.com/rnyrnyrny/a6dc926ae11951b753ecd66c00695397

// thanks to:
// https://studygolang.com/articles/17394
// https://stackoverflow.com/questions/54395407/zap-logging-with-1-customized-config-and-2-lumberjack
package logger

import (
	"fmt"
	"net/url"

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

const (
	// DPanic, Panic and Fatal level can not be set by user
	DebugLevelStr   string = "debug"
	InfoLevelStr    string = "info"
	WarningLevelStr string = "warning"
	ErrorLevelStr   string = "error"
)

var (
	globalLogger *zap.Logger
	devMode      bool = false
)

type lumberjackSink struct {
	*lumberjack.Logger
}

func (lumberjackSink) Sync() error {
	return nil
}

func Init(logLevel string, logFile string, dev bool) error {
	devMode = dev
	var level zapcore.Level
	switch logLevel {
	case DebugLevelStr:
		level = zap.DebugLevel
	case InfoLevelStr:
		level = zap.InfoLevel
	case WarningLevelStr:
		level = zap.WarnLevel
	case ErrorLevelStr:
		level = zap.ErrorLevel
	default:
		return fmt.Errorf("unknown log level %s", logLevel)
	}
	encoderConfig := zapcore.EncoderConfig{
		TimeKey:        "ts",
		LevelKey:       "level",
		NameKey:        "logger",
		CallerKey:      "caller",
		MessageKey:     "msg",
		StacktraceKey:  "stacktrace",
		LineEnding:     zapcore.DefaultLineEnding,
		EncodeLevel:    zapcore.LowercaseLevelEncoder,
		EncodeTime:     zapcore.ISO8601TimeEncoder,
		EncodeDuration: zapcore.SecondsDurationEncoder,
		EncodeCaller:   zapcore.ShortCallerEncoder,
	}
	ll := lumberjack.Logger{
		Filename:   logFile,
		MaxSize:    1024, //MB
		MaxBackups: 30,
		MaxAge:     90, //days
		Compress:   true,
	}
	zap.RegisterSink("lumberjack", func(*url.URL) (zap.Sink, error) {
		return lumberjackSink{
			Logger: &ll,
		}, nil
	})
	loggerConfig := zap.Config{
		Level:         zap.NewAtomicLevelAt(level),
		Development:   dev,
		Encoding:      "console",
		EncoderConfig: encoderConfig,
		OutputPaths:   []string{fmt.Sprintf("lumberjack:%s", logFile)},
	}
	_globalLogger, err := loggerConfig.Build()
	if err != nil {
		panic(fmt.Sprintf("build zap logger from config error: %v", err))
	}
	zap.ReplaceGlobals(_globalLogger)
	globalLogger = _globalLogger
	return nil
}

func NewSugar(name string) *zap.SugaredLogger {
	return globalLogger.Named(name).Sugar()
}