feat: scaffold MySQL services with lifecycle and readiness checks

database/database.go

@@ -93,6 +93,9 @@ type DB struct {
 }
 
 func Open(ctx context.Context, cfg Config) (*DB, error) {
+	if ctx == nil {
+		ctx = context.Background()
+	}
 	if err := cfg.Validate(); err != nil {
 		return nil, err
 	}
@@ -103,9 +106,9 @@ func Open(ctx context.Context, cfg Config) (*DB, error) {
 	if cfg.MaxOpenConns > 0 {
 		db.SetMaxOpenConns(cfg.MaxOpenConns)
 	}
-	if cfg.MaxIdleConns > 0 {
-		db.SetMaxIdleConns(cfg.MaxIdleConns)
-	}
+	// 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)
 	db.SetConnMaxLifetime(cfg.ConnMaxLifetime)
 	db.SetConnMaxIdleTime(cfg.ConnMaxIdleTime)
 	checkCtx, cancel := context.WithTimeout(ctx, cfg.PingTimeout)
@@ -123,7 +126,12 @@ func (db *DB) Health(ctx context.Context) error {
 	if db == nil || db.DB == nil {
 		return errors.New("database is not initialized")
 	}
-	return db.PingContext(ctx)
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	checkCtx, cancel := context.WithTimeout(ctx, db.config.PingTimeout)
+	defer cancel()
+	return db.PingContext(checkCtx)
 }
 
 // InTx commits only when work returns nil. Any work error or panic rolls back.