Go language uses zap log Library

install Zap Log Library

go get -u go.uber.org/zap

To configure Zap Logger

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. It's 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 terminal interface of the application .

package main

import (
	"go.uber.org/zap"
	"net/http"
)

var logger *zap.Logger

func main() {
    
	InitLogger()
	// Sync  Call the underlying layer Core Of  Sync  Method , Flush all buffered log entries . The application should be careful to call... Before exiting  Sync.
	defer logger.Sync()

	//  Assign to  URL  send out  GET  request , Print log information based on success or error results 
	simpleHttpGet("www.baidu.com")
	simpleHttpGet("http://www.baidu.com")
}

func InitLogger() {
    
	//  adopt  zap.NewProduction()  Create a  logger
	logger, _ = zap.NewProduction()
}

func simpleHttpGet(url string) {
    
	resp, err := http.Get(url)
	if err != nil {
    
		logger.Error(
			"Error fetching url..",  //  Output custom error prompt 
			zap.String("url", url),  //  Key information about this error 
			zap.Error(err))			//  Key information about this error 
	} else {
    
		logger.Info("Success..",
			zap.String("statusCode", resp.Status),
			zap.String("url", url))
		resp.Body.Close()
	}
}

You can see the level at which the log is printed , Spend time , The position , And the error messages we customized .

The syntax of the logger method ：

func (log *Logger) MethodXXX(msg string, fields ...Field) 

among MethodXXX It's a variable parameter function , It can be Info / Error/ Debug / Panic etc. . Each method accepts a message string and any number of zapcore.Field Parameters .

Every zapcore.Field It's actually a set of key values versus parameters .

Sugared Logger

Sugar Packaged Logger In order to provide more in line with people's use habits but slightly slower API. Yes Logger It's very cheap to add sugar , So a single application uses Loggers and SugaredLoggers It's reasonable , Transform between performance sensitive code at their boundaries .

package main

import (
	"go.uber.org/zap"、
	"net/http"
)

var sugarLogger *zap.SugaredLogger

func main() {
    
	InitLogger()
	// Sync  Call the underlying layer Core Of  Sync  Method , Flush all buffered log entries . The application should be careful to call... Before exiting  Sync.
	defer sugarLogger.Sync()

	//  Assign to  URL  send out  GET  request , Print log information based on success or error results 
	simpleHttpGet("www.baidu.com")
	simpleHttpGet("http://www.baidu.com")
}

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

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

customized logger

Next we will not use the default zap To configure , Instead, use custom configurations . This mainly depends on 0

func New(core zapcore.Core, options ...Option) *Logger Method to implement .

New From providing zapcore Construct a new Logger . If it's delivered zapcore.Core by nil, Then go back to the implementation of no operation .

logger := zap.New(core)

We are now going to replace the previous InitLogger function

func InitLogger() {
    
	writeSyncer := getLogWriter()
	encoder := getEncoder()
	//  Need to transfer in Encoder、WriterSyncer、Log Level
	core := zapcore.NewCore(encoder, writeSyncer, zapcore.DebugLevel)
	//  Use zap.New(…) Method to manually pass all configuration 
	logger := zap.New(core)
	sugarLogger = logger.Sugar()
}

//  Use JSON Format write log 
func getEncoder() zapcore.Encoder {
    
	return zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
}

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

Change the format of the log

take JSON Encoder Change to normal Log Encoder

//  Write logs in different formats 
func getEncoder() zapcore.Encoder {
    
	//return zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig())
	return zapcore.NewConsoleEncoder(zap.NewProductionEncoderConfig())
}

You can see that the format in the log file has changed , It's not the same as before JSON Format

More detailed configuration

We will add the following configuration

• Encode time in a form that adults can understand
• Record the log level in the log file

//  Custom log format 
func getEncoder() zapcore.Encoder {
    
	encoderConfig := zap.NewProductionEncoderConfig()
	// ISO8601TimeEncoder  Serialization time . In milliseconds  ISO8601  Format string time .
	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
	// CapitalLevelEncoder  take Level Serialize to an all uppercase string . for example , InfoLevel Serialized as “INFO”.
	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder
	return zapcore.NewConsoleEncoder(encoderConfig)
}

The log adds information about the calling function

//  Add the function to log the information of the calling function .
logger := zap.New(core, zap.AddCaller())

Complete code

package main

import (
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"net/http"
	"os"
)

var sugarLogger *zap.SugaredLogger

func main() {
    
	InitLogger()
	// Sync  Call the underlying layer Core Of  Sync  Method , Flush all buffered log entries . The application should be careful to call... Before exiting  Sync.
	defer sugarLogger.Sync()

	//  Assign to  URL  send out  GET  request , Print log information based on success or error results 
	simpleHttpGet("www.baidu.com")
	simpleHttpGet("http://www.baidu.com")
}

func InitLogger() {
    
	//  Write location 
	writeSyncer := getLogWriter()
	//  Coding format 
	encoder := getEncoder()
	//  Need to transfer in Encoder、WriterSyncer、Log Level
	core := zapcore.NewCore(encoder, writeSyncer, zapcore.DebugLevel)
	//  Use zap.New(…) Method to manually pass all configuration 
	//  increase  Caller  Information 
	logger := zap.New(core, zap.AddCaller())
	sugarLogger = logger.Sugar()
}

//  Custom log format 
func getEncoder() zapcore.Encoder {
    
	encoderConfig := zap.NewProductionEncoderConfig()
	// ISO8601TimeEncoder  Serialization time . In milliseconds  ISO8601  Format string time .
	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
	// CapitalLevelEncoder  take Level Serialize to an all uppercase string . for example , InfoLevel Serialized as “INFO”.
	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder
	return zapcore.NewConsoleEncoder(encoderConfig)
}

//  Write log to  test.log  In file 
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 {
    
		sugarLogger.Errorf(
			"Error fetching url..",
			zap.String("url", url),
			zap.Error(err))
	} else {
    
		sugarLogger.Infof("Success..",
			zap.String("statusCode", resp.Status),
			zap.String("url", url))
		resp.Body.Close()
	}
}

Cutting log

Execute the following command to install Lumberjack

go get -u github.com/natefinch/lumberjack

If only one file is used for logging , Then the file will get bigger and bigger , Finally, it is inconvenient to locate the error . So we need to split the log , For example, divide according to time , A log file records the information of the day .

//  stay zap Add Lumberjack Support 
func getLogWriter() zapcore.WriteSyncer {
    
	lumberJackLogger := &lumberjack.Logger{
    
		Filename:   "./test.log", 	//  Location of log files 
		MaxSize:    1,     			//  With  MB  In units of 
		MaxBackups: 5,     			//  Before cutting , Maximum log file size （ With MB In units of ）
		MaxAge:     30,    			//  Maximum number of days to keep old files 
		Compress:   false, 			//  Is it compressed? / Filing old documents 
	}
	return zapcore.AddSync(lumberJackLogger)
}

Complete code

package main

import (
	"github.com/natefinch/lumberjack"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"net/http"
)

var (
	sugarLogger *zap.SugaredLogger
)

func main() {
    
	InitLogger()
	defer sugarLogger.Sync() //  Refresh stream , Write log to file 
    //  Cycle write log , Here, in order to meet the cutting requirements, the cycle is recorded  100000  Time 
	for i := 0; i < 100000; i++ {
    
		sugarLogger.Infof("this is a test")
	}

}

func InitLogger() {
    
	writeSyncer := getLogWriter()
	encoder := getEncoder()
	core := zapcore.NewCore(encoder, writeSyncer, zapcore.DebugLevel)
	logger := zap.New(core, zap.AddCaller())
	sugarLogger = logger.Sugar()
}

func getEncoder() zapcore.Encoder {
    
	encoderConfig := zap.NewProductionEncoderConfig()
	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder
	return zapcore.NewConsoleEncoder(encoderConfig)
}

//  stay zap Add Lumberjack Support 
func getLogWriter() zapcore.WriteSyncer {
    
	lumberJackLogger := &lumberjack.Logger{
    
		Filename:   "./test.log",
		MaxSize:    1,     //  With  MB  In units of 
		MaxBackups: 5,     //  Before cutting , Maximum log file size （ With MB In units of ）
		MaxAge:     30,    //  Maximum number of days to keep old files 
		Compress:   false, //  Is it compressed? / Filing old documents 
	}
	return zapcore.AddSync(lumberJackLogger)
}

Reference resources

• stay Go Used in language projects Zap Log Library | Li Wenzhou's blog (liwenzhou.com)