feat: support database connectors and HTTP server configuration

database/database.go

@@ -23,13 +23,14 @@ type Config struct {
 	PingTimeout     time.Duration `json:"pingTimeout"`
 }
 
-func DefaultConfig() Config {
-	return Config{
-		MaxOpenConns:    10,
-		MaxIdleConns:    5,
-		ConnMaxLifetime: 30 * time.Minute,
-		ConnMaxIdleTime: 5 * time.Minute,
-		PingTimeout:     5 * time.Second,
+func DefaultConfig() Config { return DefaultPoolConfig().config() }
+
+// PoolConfig returns driver-independent connection pool settings.
+func (c Config) PoolConfig() PoolConfig {
+	return PoolConfig{
+		MaxOpenConns: c.MaxOpenConns, MaxIdleConns: c.MaxIdleConns,
+		ConnMaxLifetime: c.ConnMaxLifetime, ConnMaxIdleTime: c.ConnMaxIdleTime,
+		PingTimeout: c.PingTimeout,
 	}
 }
 
@@ -83,16 +84,7 @@ func (c Config) Validate() error {
 	if strings.TrimSpace(c.DSN) == "" {
 		return errors.New("database DSN is required")
 	}
-	if c.MaxOpenConns < 0 || c.MaxIdleConns < 0 {
-		return errors.New("database pool limits cannot be negative")
-	}
-	if c.MaxIdleConns > c.MaxOpenConns && c.MaxOpenConns > 0 {
-		return errors.New("max idle connections cannot exceed max open connections")
-	}
-	if c.ConnMaxLifetime < 0 || c.ConnMaxIdleTime < 0 || c.PingTimeout <= 0 {
-		return errors.New("database timeouts are invalid")
-	}
-	return nil
+	return c.PoolConfig().Validate()
 }
 
 // DB owns a connection pool and exposes the embedded database/sql methods.
@@ -112,23 +104,30 @@ func Open(ctx context.Context, cfg Config) (*DB, error) {
 	if err != nil {
 		return nil, fmt.Errorf("open database: %w", err)
 	}
-	if cfg.MaxOpenConns > 0 {
-		db.SetMaxOpenConns(cfg.MaxOpenConns)
-	}
-	// database/sql uses zero to disable idle connections; do not leave its
-	// default pool size in place when the caller explicitly chooses zero.
-	db.SetMaxIdleConns(cfg.MaxIdleConns)
+	return initializePool(ctx, db, cfg)
+}
+
+// initializePool is the shared ownership boundary for both creation paths.
+// All configuration is validated before creating the sql.DB.
+func initializePool(ctx context.Context, db *sql.DB, cfg Config) (*DB, error) {
+	db.SetMaxOpenConns(cfg.MaxOpenConns)
+	db.SetMaxIdleConns(cfg.MaxIdleConns) // Zero explicitly disables idle connections.
 	db.SetConnMaxLifetime(cfg.ConnMaxLifetime)
 	db.SetConnMaxIdleTime(cfg.ConnMaxIdleTime)
 	checkCtx, cancel := context.WithTimeout(ctx, cfg.PingTimeout)
 	defer cancel()
 	if err := db.PingContext(checkCtx); err != nil {
-		_ = db.Close()
-		return nil, fmt.Errorf("ping database: %w", err)
+		pingErr := fmt.Errorf("ping database: %w", err)
+		if closeErr := db.Close(); closeErr != nil {
+			return nil, errors.Join(pingErr, fmt.Errorf("close database after failed ping: %w", closeErr))
+		}
+		return nil, pingErr
 	}
 	return &DB{DB: db, config: cfg}, nil
 }
 
+// Config returns the original DSN configuration. Pools opened with a Connector
+// have empty Driver/DSN fields; their connector cannot be reconstructed from Config.
 func (db *DB) Config() Config { return db.config }
 
 func (db *DB) Health(ctx context.Context) error {