initialize log level when import log package

log/level.go

@@ -15,6 +15,10 @@
 
 package log
 
+import (
+	"fmt"
+)
+
 // Level ...
 type Level int
 
@@ -31,19 +35,41 @@ const (
 	FatalLevel
 )
 
-func (l Level) string() string {
+func (l Level) string() (lvl string) {
 	switch l {
 	case DebugLevel:
-		return "DEBUG"
+		lvl = "DEBUG"
 	case InfoLevel:
-		return "INFO"
+		lvl = "INFO"
 	case WarningLevel:
-		return "WARNING"
+		lvl = "WARNING"
 	case ErrorLevel:
-		return "ERROR"
+		lvl = "ERROR"
 	case FatalLevel:
-		return "FATAL"
+		lvl = "FATAL"
+	default:
+		lvl = "UNKNOWN"
 	}
 
-	return "unknown"
+	return
+}
+
+func parseLevel(lvl string) (level Level, err error) {
+
+	switch lvl {
+	case "debug":
+		level = DebugLevel
+	case "info":
+		level = InfoLevel
+	case "warning":
+		level = WarningLevel
+	case "error":
+		level = ErrorLevel
+	case "fatal":
+		level = FatalLevel
+	default:
+		err = fmt.Errorf("invalid log level: %s", lvl)
+	}
+
+	return
 }

log/logger.go

@@ -24,7 +24,25 @@ import (
 	"time"
 )
 
-var logger = New(os.Stdout, NewTextFormatter(""), WarningLevel)
+var logger = New(os.Stdout, NewTextFormatter(), WarningLevel)
+
+func init() {
+	// TODO add item in configuaration file
+	lvl := os.Getenv("LOG_LEVEL")
+	if len(lvl) == 0 {
+		logger.SetLevel(InfoLevel)
+		return
+	}
+
+	level, err := parseLevel(lvl)
+	if err != nil {
+		logger.SetLevel(InfoLevel)
+		return
+	}
+
+	logger.SetLevel(level)
+
+}
 
 // Logger provides a struct with fields that describe the details of logger.
 type Logger struct {

log/textformatter.go

@@ -27,14 +27,10 @@ type TextFormatter struct {
 	timeFormat string
 }
 
-// NewTextFormatter returns a customized TextFormatter
-func NewTextFormatter(timeFormat string) *TextFormatter {
-	if len(timeFormat) == 0 {
-		timeFormat = defaultTimeFormat
-	}
-
+// NewTextFormatter returns a TextFormatter, the format of time is time.RFC3339
+func NewTextFormatter() *TextFormatter {
 	return &TextFormatter{
-		timeFormat: timeFormat,
+		timeFormat: defaultTimeFormat,
 	}
 }
 
@@ -58,3 +54,9 @@ func (t *TextFormatter) Format(r *Record) (b []byte, err error) {
 
 	return
 }
+
+func (t *TextFormatter) SetTimeFormat(fmt string) {
+	if len(fmt) != 0 {
+		t.timeFormat = fmt
+	}
+}