Add logger

logger/logger.go

@@ -0,0 +1,37 @@
+// Copyright 2017 Frédéric Guillot. All rights reserved.
+// Use of this source code is governed by the Apache 2.0
+// license that can be found in the LICENSE file.
+
+package logger
+
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+// Debug sends a debug log message.
+func Debug(format string, v ...interface{}) {
+	formatMessage("DEBUG", format, v...)
+}
+
+// Info sends an info log message.
+func Info(format string, v ...interface{}) {
+	formatMessage("INFO", format, v...)
+}
+
+// Error sends an error log message.
+func Error(format string, v ...interface{}) {
+	formatMessage("ERROR", format, v...)
+}
+
+// Fatal sends a fatal log message and stop the execution of the program.
+func Fatal(format string, v ...interface{}) {
+	formatMessage("FATAL", format, v...)
+	os.Exit(1)
+}
+
+func formatMessage(level, format string, v ...interface{}) {
+	prefix := fmt.Sprintf("[%s] [%s] ", time.Now().Format("2006-01-02T15:04:05"), level)
+	fmt.Fprintf(os.Stderr, prefix+format+"\n", v...)
+}