使用python连接到群集时出错

Question

我正在通过Dockers使用Cassandra并且我创建了节点，当我启动节点时，它工作正常，我也可以使用cqlsh运行查询。但是当我尝试连接python（Pycharm）和cassandra时，它给了我错误。请提出你的建议可能是错的。我指定的联系点是我的节点ip之一。我还检查了节点及其启动和运行。我无法理解为什么它会给我这个错误。

from cassandra.cluster import Cluster
cluster= Cluster(contact_points=[ "172.17.0.2"],port=7000)
session=cluster.connect()
row= session.execute(
   """
   CREATE KEYSPACE IF NOT EXISTS demo WITH REPLICATION = {
       'class':SimpleStrategy,
       'replication_factor':3
   }
   """
   )

错误

session=cluster.connect()
 File "cassandra/cluster.py", line 1247, in cassandra.cluster.Cluster.connect
 File "cassandra/cluster.py", line 1283, in cassandra.cluster.Cluster.connect
 File "cassandra/cluster.py", line 1270, in cassandra.cluster.Cluster.connect
 File "cassandra/cluster.py", line 2773, in cassandra.cluster.ControlConnection.connect
 File "cassandra/cluster.py", line 2816, in cassandra.cluster.ControlConnection._reconnect_internal
cassandra.cluster.NoHostAvailable: ('Unable to connect to any servers', {'172.17.0.2': ConnectionShutdown('Connection to 172.17.0.2 was closed',)})