To connect to PostgreSQL® most frameworks accept a connection URI that begins with postgres://, this is not the case with SQLAlchemy that requires the connection URI to begin with postgresql://.

To handle this situation we added this feature in our buildpack: if we detect that you’re using SQLAlchemy (to do so we check the presence of sqlalchemy in the files requirements.txt or Pipfile), we’re adding a new environment variables SCALINGO_POSTGRESQL_ALCHEMY_URL with the right format.