sqlalchemy 构建mysql , s3, snowflake 通用连接

项目在做mysql 到snowflake的迁移， 做一个通用连接模块适配不同数据库系统的建联

早期sqlalchemy目标是提供能兼容众多数据库（如 SQLite、MySQL、Postgres、Oracle、MS-SQL、SQLServer 和 Firebird）的企业级持久性模型

代码如下:

1. 因为mysql是搭建在云端，需要SSH桥接，加入ssh_tunnel 连接库

"""SSH Tunnel Connector"""
import logging
import os

import sshtunnel

from modules.utils.configloader import load_config
from modules.utils.constants import SSHServer

logger = logging.getLogger(__name__)

INSTANCE = load_config(f'config/profiles/{os.environ.get("ENV", "bdpqa")}')


class SSHTunnel:
    """SSH Tunnel Class
    """

    def __init__(self, ssh_address=None, username=None, remote_bind_address=None):
        """Initialize
        """
        rds_items = INSTANCE.data.get('customer')
        self.tunnel = sshtunnel.SSHTunnelForwarder(
            ssh_address_or_host=ssh_address or rds_items[SSHServer.SSH_ADDRESS.value],
            ssh_username=username or rds_items[SSHServer.SSH_USERNAME.value],
            ssh_pkey=rds_items[SSHServer.SSH_PKEY.value],
            remote_bind_address=(remote_bind_address or rds_items[SSHServer.REMOTE_BIND_ADDRESS.value],
                                 rds_items[SSHServer.REMOTE_PORT.value]),
            local_bind_address=(rds_items[SSHServer.LOCAL_BIND_ADDRESS.value],
                                rds_items[SSHServer.LOCAL_PORT.value])
        )
        sshtunnel.SSH_TIMEOUT = 18000.0
        sshtunnel.TUNNEL_TIMEOUT = 18000.0

    def start(self):
        """Start Connection"""
        try:
            self.tunnel.start()
            logger.info("Tunnel Connection Started")

        except Exception as exception:
            logger.error(exception)

    def stop(self):
        """Stop Connection"""
        try:
            self.tunnel.stop()
            logger.info("Tunnel Connection Finished")

        except Exception as exception:
            logger.error(exception)

2. database_connect 主代码， , SQL返回结果为Pandas dataframe格式

import pandas as pd
import sqlalchemy

from modules.utils.configloa