db: connection retry logic

database/main.go

@@ -16,27 +16,7 @@ import (
 var DB *gorm.DB
 
 func Start() {
-	host := os.Getenv("DB_HOST")
-	port := os.Getenv("DB_PORT")
-	user := os.Getenv("DB_USER")
-	password := os.Getenv("DB_PASSWORD")
-	dbname := os.Getenv("DB_NAME")
-
-	connectionString := fmt.Sprintf(
-		"%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True",
-		user, password, host, port, dbname,
-	)
-	db, err := gorm.Open(mysql.Open(connectionString), &gorm.Config{
-		Logger: logger.Default.LogMode(logger.Silent),
-		NowFunc: func() time.Time {
-			utc, _ := time.LoadLocation("Europe/Rome")
-			return time.Now().In(utc)
-		},
-	})
-	if err != nil {
-		log.Fatalf("failed to connect to database: %v", err)
-	}
-	DB = db
+	DB = connect()
 	sqlDB, err := DB.DB()
 	if err != nil {
 		log.Fatalf("failed to get database connection: %v", err)
@@ -54,6 +34,47 @@ func Start() {
 	}
 }
 
+func connect() *gorm.DB {
+	host := os.Getenv("DB_HOST")
+	port := os.Getenv("DB_PORT")
+	user := os.Getenv("DB_USER")
+	password := os.Getenv("DB_PASSWORD")
+	dbname := os.Getenv("DB_NAME")
+
+	connectionString := fmt.Sprintf(
+		"%s:%s@tcp(%s:%s)/%s?charset=utf8mb4&parseTime=True",
+		user, password, host, port, dbname,
+	)
+
+	var conn *gorm.DB
+	var err error
+
+	maxRetries := 10
+	retryCount := 0
+
+	for retryCount < maxRetries {
+		conn, err = gorm.Open(mysql.Open(connectionString), &gorm.Config{
+			Logger: logger.Default.LogMode(logger.Silent),
+			NowFunc: func() time.Time {
+				utc, _ := time.LoadLocation("Europe/Rome")
+				return time.Now().In(utc)
+			},
+		})
+		if err == nil {
+			break
+		}
+		retryCount++
+		log.Printf("failed to connect to database (attempt %d/%d)", retryCount, maxRetries)
+		if retryCount < maxRetries {
+			time.Sleep(2 * time.Second)
+		}
+	}
+	if err != nil {
+		log.Fatalf("failed to connect to database after %d attempts: %v", maxRetries, err)
+	}
+	return conn
+}
+
 func migrateDatabase() error {
 	err := DB.AutoMigrate(
 		&models.Media{},