使用Python驱动连接Astra DB失败，求助解决网络不可达问题

严格按照AstraDB Python驱动文档操作，代码如下：

cloud_config= {
        'secure_connect_bundle': 'secure-connect-test-warehouse.zip'
}

logging.basicConfig(level=logging.DEBUG)

auth_provider = PlainTextAuthProvider(my_id, my_secret)
cluster = Cluster(cloud=cloud_config, auth_provider=auth_provider)
session = cluster.connect()

row = session.execute("select release_version from system.local").one()
if row:
    print(row[0])
else:
    print("An error occurred.")

执行后出现错误：

File "connect_database.py", line 23, in <module>
    session = cluster.connect()
  File "cassandra/cluster.py", line 1677, in cassandra.cluster.Cluster.connect
  File "cassandra/cluster.py", line 1713, in cassandra.cluster.Cluster.connect
  File "cassandra/cluster.py", line 1700, in cassandra.cluster.Cluster.connect
  File "cassandra/cluster.py", line 3507, in cassandra.cluster.ControlConnection.connect
  File "cassandra/cluster.py", line 3552, in cassandra.cluster.ControlConnection._reconnect_internal
cassandra.cluster.NoHostAvailable: ('Unable to connect to any servers
OSError(101, "Tried connecting to [(...', ..., 0, 0)]. Last error: Network is unreachable")})

已尝试将control_connection_timeout从默认2.0调整为10，问题仍未解决，求解决方案。

• 检查Secure Connect Bundle文件
  确认secure-connect-test-warehouse.zip路径正确，文件未损坏。可重新从AstraDB控制台下载最新的bundle文件替换原文件，下载时确保文件完整。

• 验证认证信息正确性
  确认my_id和my_secret是AstraDB的客户端ID和客户端密钥，而非用户名密码。可在AstraDB控制台的「Connect」页面获取正确凭据。

• 排查网络限制

  • 检查本地防火墙、杀毒软件是否拦截Python程序的网络请求，临时关闭防火墙测试连接。
  • 确认所在网络未屏蔽443端口（AstraDB使用该端口通信，需确保出站443端口开放）。
  • 若在企业网络环境，联系IT部门确认是否有代理或准入规则限制外部连接，必要时配置代理：

    cloud_config= {
            'secure_connect_bundle': 'secure-connect-test-warehouse.zip',
            'proxy_url': 'http://your-proxy-host:port'
    }
    

• 检查驱动版本兼容性
  确认cassandra-driver版本与AstraDB兼容，建议安装4.15.x及以上版本，执行以下命令升级：

  pip install --upgrade cassandra-driver
  

• 调整连接参数并启用重试
  同时设置connect_timeout和control_connection_timeout，并配置重试策略：

  from cassandra.cluster import Cluster, ExecutionProfile, EXEC_PROFILE_DEFAULT
  from cassandra.auth import PlainTextAuthProvider
  from cassandra.policies import DowngradingConsistencyRetryPolicy
  
  profile = ExecutionProfile(
      retry_policy=DowngradingConsistencyRetryPolicy(),
      connect_timeout=15,
      control_connection_timeout=15
  )
  
  cloud_config= {
          'secure_connect_bundle': 'secure-connect-test-warehouse.zip'
  }
  
  auth_provider = PlainTextAuthProvider(my_id, my_secret)
  cluster = Cluster(
      cloud=cloud_config,
      auth_provider=auth_provider,
      execution_profiles={EXEC_PROFILE_DEFAULT: profile}
  )
  session = cluster.connect()
  

内容的提问来源于stack exchange，提问作者Amine SAIHI