add logging

logger.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"time"
+
+	"github.com/gin-gonic/gin"
+	"github.com/sirupsen/logrus"
+)
+
+// Logger is the global logger instance
+var Logger *logrus.Logger
+
+// InitLogger initializes the structured logger with file output
+func InitLogger(config *Config) error {
+	Logger = logrus.New()
+
+	// Set log level based on configuration
+	level, err := logrus.ParseLevel(config.LogLevel)
+	if err != nil {
+		level = logrus.InfoLevel
+	}
+	Logger.SetLevel(level)
+
+	// Set JSON formatter for structured logging
+	Logger.SetFormatter(&logrus.JSONFormatter{
+		TimestampFormat: time.RFC3339,
+		FieldMap: logrus.FieldMap{
+			logrus.FieldKeyTime:  "timestamp",
+			logrus.FieldKeyLevel: "level",
+			logrus.FieldKeyMsg:   "message",
+		},
+	})
+
+	// Create log directory if it doesn't exist
+	if err := os.MkdirAll(config.LogDir, 0755); err != nil {
+		return err
+	}
+
+	// Create log file with timestamp
+	logFile := filepath.Join(config.LogDir, "app.log")
+	file, err := os.OpenFile(logFile, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0666)
+	if err != nil {
+		return err
+	}
+
+	// Set output to both file and stdout
+	multiWriter := io.MultiWriter(os.Stdout, file)
+	Logger.SetOutput(multiWriter)
+
+	// Add default fields
+	Logger = Logger.WithFields(logrus.Fields{
+		"service":     "counter-app",
+		"environment": string(config.Environment),
+		"version":     "1.0.0",
+	}).Logger
+
+	// Log initialization
+	Logger.Info("Logger initialized successfully")
+
+	return nil
+}
+
+// GetLogger returns the global logger instance
+func GetLogger() *logrus.Logger {
+	if Logger == nil {
+		// Fallback to standard logger if not initialized
+		logrus.SetFormatter(&logrus.JSONFormatter{
+			TimestampFormat: time.RFC3339,
+		})
+		return logrus.StandardLogger()
+	}
+	return Logger
+}
+
+// LoggingMiddleware creates a Gin middleware for HTTP request logging
+func LoggingMiddleware() gin.HandlerFunc {
+	return gin.LoggerWithFormatter(func(param gin.LogFormatterParams) string {
+		// Create structured log entry
+		entry := Logger.WithFields(logrus.Fields{
+			"method":     param.Method,
+			"path":       param.Path,
+			"status":     param.StatusCode,
+			"latency":    param.Latency.String(),
+			"client_ip":  param.ClientIP,
+			"user_agent": param.Request.UserAgent(),
+			"timestamp":  param.TimeStamp.Format(time.RFC3339),
+		})
+
+		// Set log level based on status code
+		switch {
+		case param.StatusCode >= 500:
+			entry.Error("HTTP Request")
+		case param.StatusCode >= 400:
+			entry.Warn("HTTP Request")
+		default:
+			entry.Info("HTTP Request")
+		}
+
+		// Return empty string since we're handling logging ourselves
+		return ""
+	})
+}