Flask SQLAlchemy setup dynamic URI
You can make a custom builder for the session that will re-create the engine and scoped session when your rules dictate it. Something like
class SessionManager(object): def __init__(self): self.session = None def get_session(self): # return existing session or make a new engine and scoped_sessionTo make this class transparent, use Werkzeug's LocalProxy. The code that uses the sessions won't have to change at all.
session_manager = SessionManager()db_session = LocalProxy(session_manager.get_session)