Go In language logger and zap Log Library

In the process of software development , Critical logging is required , Facilitate later audit and troubleshooting .

A good logger should have the following functions ：

• Logs are written to files instead of console output
• Log cutting - By file size 、 Cutting log files such as time or interval
• Supports different log levels , Such as ：INFO,DEBUG,ERROR etc.
• Can print basic information , Such as calling file / Function name and line number , Log time, etc

Go Logger

Configure log output file

func SetupLogger() {
    
	logFileLocation, _ := os.OpenFile("./test.log", os.O_CREATE|os.O_APPEND|os.O_RDWR, 0744)
	log.SetOutput(logFileLocation)
}

Write an example , Build one to URL Of HTTP Connect , Record status code / Errors are logged to the log file

func simpleHttpGet(url string) {
    
	resp, err := http.Get(url)
	if err != nil {
    
		log.Printf("Error fetching url %s : %s", url, err.Error())
	} else {
    
		log.Printf("Status Code for %s : %s", url, resp.Status)
		resp.Body.Close()
	}
}

main function , Execute the sample

func main() {
    
	SetupLogger()
	simpleHttpGet("www.google.com")
	simpleHttpGet("http://www.google.com")
}

notice test.log The file is created , And recorded the following

2022/04/22 11:33:52 Error fetching url www.google.com : Get "www.google.com": unsupported protocol scheme ""
2022/04/22 11:33:53 Status Code for http://www.google.com : 200 OK

Zap Logger

go get -u go.uber.org/zap

Zap There are two types of loggers available - Sugared Logger and Logger

In a context where performance is good but not critical , Use SugaredLogger. It's faster than other structured logging packages 4-10 times , And support structured and printf Style logging

In the context where every microsecond and every memory allocation is important , Use Logger. Even better than SugaredLogger faster , Less memory allocation , But it only supports strongly typed structured logging

Logger

• By calling zap.NewProduction()/zap.NewDevelopment() perhaps zap.Example() Create a Logger
• Each of the above functions will create a logger. The only difference is that it will record different information . for example production logger Call function information is recorded by default 、 Date and time, etc
• adopt Logger call Info/Error etc.
• By default, logs are printed to the application's console Interface

var logger *zap.Logger

func main() {
    
	InitLogger()
  defer logger.Sync()
	simpleHttpGet("www.google.com")
	simpleHttpGet("http://www.google.com")
}

func InitLogger() {
    
	logger, _ = zap.NewProduction()
}

func simpleHttpGet(url string) {
    
	resp, err := http.Get(url)
	if err != nil {
    
		logger.Error(
			"Error fetching url..",
			zap.String("url", url),
			zap.Error(err))
	} else {
    
		logger.Info("Success..",
			zap.String("statusCode", resp.Status),
			zap.String("url", url))
		resp.Body.Close()
	}
}

Sugared Logger

• Most of the implementations are basically the same
• The only difference is , We call the master logger Of . Sugar() Method to get a SugaredLogger
• And then use SugaredLogger With printf Format record statement

var sugarLogger *zap.SugaredLogger

func main() {
    
	InitLogger()
	defer sugarLogger.Sync()
	simpleHttpGet("www.google.com")
	simpleHttpGet("http://www.google.com")
}

func InitLogger() {
    
    logger, _ := zap.NewProduction()
	sugarLogger = logger.Sugar()
}

func simpleHttpGet(url string) {
    
	sugarLogger.Debugf("Trying to hit GET request for %s", url)
	resp, err := http.Get(url)
	if err != nil {
    
		sugarLogger.Errorf("Error fetching URL %s : Error = %s", url, err)
	} else {
    
		sugarLogger.Infof("Success! statusCode = %s for URL %s", resp.Status, url)
		resp.Body.Close()
	}
}

customized Logger Record in a file

1. Encoder: Encoder ( How to write logs ). We will use out of the box NewJSONEncoder(), And use the preset
2. WriterSyncer: Specify where the log will be written . We use zapcore.AddSync() Function and pass in the open file handle
3. Log Level: Which level of log will be written to

var logger *zap.Logger
func main() {
    
	InitLogger()
    defer logger.Sync()
	simpleHttpGet("www.google.com")
	simpleHttpGet("http://www.google.com")
}

func InitLogger() {
    
	writeSyncer := getLogWriter()
	encoder := getEncoder()
	core := zapcore.NewCore(encoder, writeSyncer, zapcore.DebugLevel)

	logger := zap.New(core)
	// sugarLogger = logger.Sugar()
}

func getEncoder() zapcore.Encoder {
    
	return zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
}

func getLogWriter() zapcore.WriteSyncer {
    
	file, _ := os.Create("./test.log")
	return zapcore.AddSync(file)
}

func simpleHttpGet(url string) {
    
	resp, err := http.Get(url)
	if err != nil {
    
		logger.Error(
			"Error fetching url..",
			zap.String("url", url),
			zap.Error(err))
	} else {
    
		logger.Info("Success..",
			zap.String("statusCode", resp.Status),
			zap.String("url", url))
		resp.Body.Close()
	}
}

take JSON Encoder Change to normal Log Encoder, Only need to NewJSONEncoder() Change to NewConsoleEncoder()

Reference resources

[1] stay Go Used in language projects Zap Log Library ( Li Wenzhou )
[2] Go Logger
[3] Go zap