logger with helper methods (#1216)

* support unix daemon socket

* refactor(logger): logger fields changed to map[string]interface{}

* improvement(logger): adding string to Level Parser

* improvement(logger): rename ParseLevel to GetLevel

* refactor(logger): adding basic logger

adding micro default logger, and refactor logger interface

* refactor(logger): moved basic logger to top level package

* refactor(logger): adding default logger

logger/level.go

@@ -1,14 +1,24 @@
 package logger
 
+import "fmt"
+
 type Level int8
 
 const (
-	TraceLevel Level = iota - 1
+	// TraceLevel level. Designates finer-grained informational events than the Debug.
+	TraceLevel Level = iota - 2
+	// DebugLevel level. Usually only enabled when debugging. Very verbose logging.
 	DebugLevel
+	// InfoLevel is the default logging priority.
+	// General operational entries about what's going on inside the application.
 	InfoLevel
+	// WarnLevel level. Non-critical entries that deserve eyes.
 	WarnLevel
+	// ErrorLevel level. Logs. Used for errors that should definitely be noted.
 	ErrorLevel
+	// PanicLevel level, logs the message and then panics.
 	PanicLevel
+	// FatalLevel level. Logs and then calls `logger.Exit(1)`. highest level of severity.
 	FatalLevel
 )
 
@@ -24,10 +34,37 @@ func (l Level) String() string {
 		return "warn"
 	case ErrorLevel:
 		return "error"
-	case FatalLevel:
-		return "fatal"
 	case PanicLevel:
 		return "panic"
+	case FatalLevel:
+		return "fatal"
 	}
 	return ""
 }
+
+// Enabled returns true if the given level is at or above this level.
+func (l Level) Enabled(lvl Level) bool {
+	return lvl >= l
+}
+
+// GetLevel converts a level string into a logger Level value.
+// returns an error if the input string does not match known values.
+func GetLevel(levelStr string) (Level, error) {
+	switch levelStr {
+	case TraceLevel.String():
+		return TraceLevel, nil
+	case DebugLevel.String():
+		return DebugLevel, nil
+	case InfoLevel.String():
+		return InfoLevel, nil
+	case WarnLevel.String():
+		return WarnLevel, nil
+	case ErrorLevel.String():
+		return ErrorLevel, nil
+	case PanicLevel.String():
+		return PanicLevel, nil
+	case FatalLevel.String():
+		return FatalLevel, nil
+	}
+	return InfoLevel, fmt.Errorf("Unknown Level String: '%s', defaulting to NoLevel", levelStr)
+}