mongo-python-driver/test/test_replica_set_reconfig.py

# Copyright 2013-present MongoDB, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Test clients and replica set configuration changes, using mocks."""

import sys

sys.path[0:0] = [""]

from test import MockClientTest, client_context, client_knobs, unittest
from test.pymongo_mocks import MockClient
from test.utils import wait_until

from pymongo import ReadPreference
from pymongo.errors import ConnectionFailure, ServerSelectionTimeoutError


@client_context.require_connection
@client_context.require_no_load_balancer
def setUpModule():
    pass


class TestSecondaryBecomesStandalone(MockClientTest):
    # An administrator removes a secondary from a 3-node set and
    # brings it back up as standalone, without updating the other
    # members' config. Verify we don't continue using it.
    def test_client(self):
        c = MockClient(
            standalones=[],
            members=["a:1", "b:2", "c:3"],
            mongoses=[],
            host="a:1,b:2,c:3",
            replicaSet="rs",
            serverSelectionTimeoutMS=100,
            connect=False,
        )
        self.addCleanup(c.close)

        # C is brought up as a standalone.
        c.mock_members.remove("c:3")
        c.mock_standalones.append("c:3")

        # Fail over.
        c.kill_host("a:1")
        c.kill_host("b:2")

        with self.assertRaises(ServerSelectionTimeoutError):
            c.db.command("ping")
        self.assertEqual(c.address, None)

        # Client can still discover the primary node
        c.revive_host("a:1")
        wait_until(lambda: c.address is not None, "connect to primary")
        self.assertEqual(c.address, ("a", 1))

    def test_replica_set_client(self):
        c = MockClient(
            standalones=[],
            members=["a:1", "b:2", "c:3"],
            mongoses=[],
            host="a:1,b:2,c:3",
            replicaSet="rs",
        )
        self.addCleanup(c.close)

        wait_until(lambda: ("b", 2) in c.secondaries, 'discover host "b"')

        wait_until(lambda: ("c", 3) in c.secondaries, 'discover host "c"')

        # C is brought up as a standalone.
        c.mock_members.remove("c:3")
        c.mock_standalones.append("c:3")

        wait_until(lambda: set([("b", 2)]) == c.secondaries, "update the list of secondaries")

        self.assertEqual(("a", 1), c.primary)


class TestSecondaryRemoved(MockClientTest):
    # An administrator removes a secondary from a 3-node set *without*
    # restarting it as standalone.
    def test_replica_set_client(self):
        c = MockClient(
            standalones=[],
            members=["a:1", "b:2", "c:3"],
            mongoses=[],
            host="a:1,b:2,c:3",
            replicaSet="rs",
        )
        self.addCleanup(c.close)

        wait_until(lambda: ("b", 2) in c.secondaries, 'discover host "b"')
        wait_until(lambda: ("c", 3) in c.secondaries, 'discover host "c"')

        # C is removed.
        c.mock_hello_hosts.remove("c:3")
        wait_until(lambda: set([("b", 2)]) == c.secondaries, "update list of secondaries")

        self.assertEqual(("a", 1), c.primary)


class TestSocketError(MockClientTest):
    def test_socket_error_marks_member_down(self):
        # Disable background refresh.
        with client_knobs(heartbeat_frequency=999999):
            c = MockClient(
                standalones=[],
                members=["a:1", "b:2"],
                mongoses=[],
                host="a:1",
                replicaSet="rs",
                serverSelectionTimeoutMS=100,
            )
            self.addCleanup(c.close)

            wait_until(lambda: len(c.nodes) == 2, "discover both nodes")

            # b now raises socket.error.
            c.mock_down_hosts.append("b:2")
            self.assertRaises(
                ConnectionFailure,
                c.db.collection.with_options(read_preference=ReadPreference.SECONDARY).find_one,
            )

            self.assertEqual(1, len(c.nodes))


class TestSecondaryAdded(MockClientTest):
    def test_client(self):
        c = MockClient(
            standalones=[], members=["a:1", "b:2"], mongoses=[], host="a:1", replicaSet="rs"
        )
        self.addCleanup(c.close)

        wait_until(lambda: len(c.nodes) == 2, "discover both nodes")

        # MongoClient connects to primary by default.
        self.assertEqual(c.address, ("a", 1))
        self.assertEqual(set([("a", 1), ("b", 2)]), c.nodes)

        # C is added.
        c.mock_members.append("c:3")
        c.mock_hello_hosts.append("c:3")

        c.db.command("ping")

        self.assertEqual(c.address, ("a", 1))

        wait_until(
            lambda: set([("a", 1), ("b", 2), ("c", 3)]) == c.nodes, "reconnect to both secondaries"
        )

    def test_replica_set_client(self):
        c = MockClient(
            standalones=[], members=["a:1", "b:2"], mongoses=[], host="a:1", replicaSet="rs"
        )
        self.addCleanup(c.close)

        wait_until(lambda: ("a", 1) == c.primary, "discover the primary")
        wait_until(lambda: set([("b", 2)]) == c.secondaries, "discover the secondary")

        # C is added.
        c.mock_members.append("c:3")
        c.mock_hello_hosts.append("c:3")

        wait_until(lambda: set([("b", 2), ("c", 3)]) == c.secondaries, "discover the new secondary")

        self.assertEqual(("a", 1), c.primary)


if __name__ == "__main__":
    unittest.main()