로그 포맷 통일, slog 적용

backend/internal/logger/logger.go

@@ -0,0 +1,49 @@
+package logger
+
+import (
+	"log/slog"
+	"os"
+	"strings"
+)
+
+// Config holds the logger configuration
+type Config struct {
+	ServiceName string
+	Environment string // "dev", "local", "production"
+}
+
+// Init initializes the global logger with slog.
+// It detects the environment to switch between TextHandler (dev) and JSONHandler (prod).
+func Init(cfg Config) {
+	var handler slog.Handler
+
+	opts := &slog.HandlerOptions{
+		// Default level
+		Level: slog.LevelInfo,
+		// Customize attributes (Time format)
+		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+			if a.Key == slog.TimeKey {
+				return slog.String(a.Key, a.Value.Time().Format("2006-01-02 15:04:05"))
+			}
+			return a
+		},
+	}
+
+	// Adjust level and format based on environment
+	env := strings.ToLower(cfg.Environment)
+	if env == "dev" || env == "local" || env == "development" {
+		opts.Level = slog.LevelDebug
+		handler = slog.NewTextHandler(os.Stdout, opts)
+	} else {
+		// Production defaults to JSON
+		handler = slog.NewJSONHandler(os.Stdout, opts)
+	}
+
+	// Create logger with common attributes
+	logger := slog.New(handler).With(
+		slog.String("svc", cfg.ServiceName),
+	)
+
+	// Set as global default logger
+	slog.SetDefault(logger)
+}