gopackagebase/logging.go

package gopackagebase

import (
	"fmt"
	"log"
	"os"
	"time"
)

type logWriter struct {
	utcTime     bool
	writeToFile bool
	logFile     *os.File
}

func (w *logWriter) Write(bytes []byte) (int, error) {
	t := time.Now()
	if w.utcTime {
		t = t.UTC()
	}
	format := t.Format(time.RFC3339)
	return fmt.Fprintf(w.logFile, "%v %v", format, string(bytes))
}

func (w *logWriter) Cleanup() {
	defer w.logFile.Close()
}

func SetupLogging(writeToFile bool, utcTime bool, logFilename string) (*logWriter, error) {
	var err error
	log.SetFlags(0)

	logFile := os.Stdout
	if writeToFile {
		logFile, err = os.OpenFile(logFilename, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
		if err != nil {
			return nil, err
		}
	}

	writer := &logWriter{
		utcTime:     utcTime,
		writeToFile: writeToFile,
		logFile:     logFile,
	}
	log.SetOutput(writer)

	return writer, nil
}