Merge pull request apache#1096 from datastax/python-1265

PYTHON-1265: Fix the default cqlengine connection mechanism to work with Astra

Author: aboudreault

CHANGELOG.rst

@@ -6,6 +6,7 @@ Features
 --------
 * Ensure the driver can connect when invalid peer hosts are in system.peers (PYTHON-1260)
 * Implement protocol v5 checksumming (PYTHON-1258)
+* Fix the default cqlengine connection mechanism to work with Astra (PYTHON-1265)
 
 Bug Fixes
 ---------

cassandra/cqlengine/connection.py

@@ -98,7 +98,13 @@ def setup(self):
         if self.lazy_connect:
             return
 
-        self.cluster = Cluster(self.hosts, **self.cluster_options)
+        if 'cloud' in self.cluster_options:
+            if self.hosts:
+                log.warning("Ignoring hosts %s because a cloud config was provided.", self.hosts)
+            self.cluster = Cluster(**self.cluster_options)
+        else:
+            self.cluster = Cluster(self.hosts, **self.cluster_options)
+
         try:
             self.session = self.cluster.connect()
             log.debug(format_log_context("connection initialized with internally created session", connection=self.name))
@@ -301,6 +307,8 @@ def set_session(s):
     log.debug("cqlengine default connection initialized with %s", s)
 
 
+# TODO next major: if a cloud config is specified in kwargs, hosts will be ignored.
+# This function should be refactored to reflect this change. PYTHON-1265
 def setup(
         hosts,
         default_keyspace,

docs/cloud.rst

@@ -54,3 +54,36 @@ Limitations
 Event loops
 ^^^^^^^^^^^
 Evenlet isn't yet supported for python 3.7+ due to an `issue in Eventlet <https://github.com/eventlet/eventlet/issues/526>`_.
+
+
+CqlEngine
+=========
+
+When using the object mapper, you can configure cqlengine with :func:`~.cqlengine.connection.set_session`:
+
+.. code:: python
+
+  from cassandra.cqlengine import connection
+  ...
+
+  c = Cluster(cloud={'secure_connect_bundle':'/path/to/secure-connect-test.zip'},
+              auth_provider=PlainTextAuthProvider('user', 'pass'))
+  s = c.connect('myastrakeyspace')
+  connection.set_session(s)
+  ...
+
+If you are using some third-party libraries (flask, django, etc.), you might not be able to change the
+configuration mechanism. For this reason, the `hosts` argument of the default
+:func:`~.cqlengine.connection.setup` function will be ignored if a `cloud` config is provided:
+
+.. code:: python
+
+  from cassandra.cqlengine import connection
+  ...
+
+  connection.setup(
+    None,  # or anything else
+    "myastrakeyspace", cloud={
+      'secure_connect_bundle':'/path/to/secure-connect-test.zip'
+    },
+    auth_provider=PlainTextAuthProvider('user', 'pass'))

tests/integration/cloud/test_cloud.py

@@ -13,6 +13,10 @@
 # limitations under the License
 from cassandra.datastax.cloud import parse_metadata_info
 from cassandra.query import SimpleStatement
+from cassandra.cqlengine import connection
+from cassandra.cqlengine.management import sync_table, create_keyspace_simple
+from cassandra.cqlengine.models import Model
+from cassandra.cqlengine import columns
 
 try:
     import unittest2 as unittest
@@ -30,7 +34,7 @@
 
 from mock import patch
 
-from tests.integration import requirescloudproxy, TestCluster
+from tests.integration import requirescloudproxy
 from tests.util import wait_until_not_raised
 from tests.integration.cloud import CloudProxyCluster, CLOUD_PROXY_SERVER
 
@@ -143,7 +147,7 @@ def test_resolve_and_reconnect_on_node_down(self):
             wait_until_not_raised(
                 lambda: self.assertEqual(len(self.hosts_up()), 3),
                 0.02, 250)
-            mocked_resolve.assert_called_once()
+            mocked_resolve.assert_called()
 
     def test_metadata_unreachable(self):
         with self.assertRaises(DriverException) as cm:
@@ -234,3 +238,14 @@ def test_consistency_guardrails(self):
             self.session.execute(statement)
         except InvalidRequest:
             self.fail("InvalidRequest was incorrectly raised for write query at LOCAL QUORUM!")
+
+    def test_cqlengine_can_connect(self):
+        class TestModel(Model):
+            id = columns.Integer(primary_key=True)
+            val = columns.Text()
+
+        connection.setup(None, "test", cloud={'secure_connect_bundle': self.creds})
+        create_keyspace_simple('test', 1)
+        sync_table(TestModel)
+        TestModel.objects.create(id=42, value='test')
+        self.assertEqual(len(TestModel.objects.all()), 1)