Logger Writing to Multiple Files & Stderr/Stdout - go

Question

My goal is to create a logger that I can use to output to stdout (info logs) and stderr (error logs) as well as respective files (info.log) and (errors.log) all at the same time.
I am currently using loggers in Go like the following:
package main
import (
"log"
"os"
"io"
)
func main() {
// Current method
infoLog := log.New("./data/info.log", "INFO\t", log.Ldate|log.Ltime)
errorLog := log.New("./data/errors.log", "ERROR\t", log.Ldate|log.Ltime|log.Lshortfile)
infoLog.Println("Hello INFO!")
errorLog.Println("Hello ERROR!")
// I've read about using io.MultiWriter like the following in order to write to stdout/stderr as well as a flat file at the same time
f, err := os.OpenFile("./data/info.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
if err != nil {
log.Fatalf("error opening file: %v", err)
}
defer f.Close()
wrt := io.MultiWriter(os.Stdout, f)
log.SetOutput(wrt)
log.Println("Hello World!")
}
I'd like to basically take the formatting of infoLog and errorLog (like in my first logging solution) like log.Ldate|log.Ltime and apply it to the io.MultiWriter. Is there a way to do this?

Answer 1

For logging info and error in file with standard format that other logging services such as filebeat, logstash and etc can understand it I suggest you to use github.com/sirupsen/logrus.
This package has SetFormater function to define format of output log. For example:
logrus.SetFormatter(&logrus.JSONFormatter{
FieldMap: logrus.FieldMap{
logrus.FieldKeyTime: "#timestamp",
logrus.FieldKeyMsg: "message",
logrus.FieldKeyFunc: "func",
logrus.FieldKeyFile: "file",
},
})
and you can define file for logging. For example:
file, err := os.OpenFile("payment_logs.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
And set log is very easy and standard:
logger.Info("This is an info message")
logger.Warn("This is a warning message")
logger.Error("This is an error message")