feat: validate driver with database engine

google/cloud/sql/connector/connector.py

@@ -30,8 +30,10 @@
 
 import google.cloud.sql.connector.asyncpg as asyncpg
 from google.cloud.sql.connector.client import CloudSQLClient
+from google.cloud.sql.connector.enums import DriverMapping
 from google.cloud.sql.connector.exceptions import ConnectorLoopError
 from google.cloud.sql.connector.exceptions import DnsNameResolutionError
+from google.cloud.sql.connector.exceptions import IncompatibleDriverError
 from google.cloud.sql.connector.instance import IPTypes
 from google.cloud.sql.connector.instance import RefreshAheadCache
 from google.cloud.sql.connector.instance import RefreshStrategy
@@ -321,6 +323,14 @@ async def connect_async(
         # attempt to make connection to Cloud SQL instance
         try:
             conn_info = await cache.connect_info()
+            # validate driver matches intended database engine
+            mapping = DriverMapping[driver.upper()]
+            if not conn_info.database_version.startswith(mapping.value):
+                raise IncompatibleDriverError(
+                    f"Database driver '{driver}' is incompatible with database "
+                    f"version '{conn_info.database_version}'. Given driver can "
+                    f"only be used with Cloud SQL {mapping.value} databases."
+                )
             ip_address = conn_info.get_preferred_ip(ip_type)
             # resolve DNS name into IP address for PSC
             if ip_type.value == "PSC":

google/cloud/sql/connector/enums.py

@@ -0,0 +1,24 @@
+# Copyright 2024 Google LLC
+#
+# 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.
+
+from enum import Enum
+
+
+class DriverMapping(Enum):
+    """Maps a given database driver to it's corresponding database engine."""
+
+    ASYNCPG = "POSTGRES"
+    PG8000 = "POSTGRES"
+    PYMYSQL = "MYSQL"
+    PYTDS = "SQLSERVER"

google/cloud/sql/connector/exceptions.py

@@ -70,3 +70,10 @@ class RefreshNotValidError(Exception):
     """
 
     pass
+
+
+class IncompatibleDriverError(Exception):
+    """
+    Exception to be raised when the database driver given is for the wrong
+    database engine. (i.e. asyncpg for a MySQL database)
+    """

tests/unit/test_connector.py

@@ -13,6 +13,7 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+
 import asyncio
 from typing import Union
 
@@ -25,6 +26,7 @@
 from google.cloud.sql.connector import IPTypes
 from google.cloud.sql.connector.client import CloudSQLClient
 from google.cloud.sql.connector.exceptions import ConnectorLoopError
+from google.cloud.sql.connector.exceptions import IncompatibleDriverError
 from google.cloud.sql.connector.instance import RefreshAheadCache
 
 
@@ -46,10 +48,32 @@ def test_connect_enable_iam_auth_error(
         "If you require both for your use case, please use a new "
         "connector.Connector object."
     )
-    # remove cache entrry to avoid destructor warnings
+    # remove cache entry to avoid destructor warnings
     connector._cache = {}
 
 
+async def test_connect_incompatible_driver_error(
+    fake_credentials: Credentials,
+    fake_client: CloudSQLClient,
+) -> None:
+    """Test that calling connect() with driver that is incompatible with
+    database version throws error."""
+    connect_string = "test-project:test-region:test-instance"
+    async with Connector(
+        credentials=fake_credentials, loop=asyncio.get_running_loop()
+    ) as connector:
+        connector._client = fake_client
+        # try to connect using pymysql driver to a Postgres database
+        with pytest.raises(IncompatibleDriverError) as exc_info:
+            await connector.connect_async(connect_string, "pymysql")
+        assert (
+            exc_info.value.args[0]
+            == "Database driver 'pymysql' is incompatible with database version"
+            " 'POSTGRES_15'. Given driver can only be used with Cloud SQL MYSQL"
+            " databases."
+        )
+
+
 def test_connect_with_unsupported_driver(fake_credentials: Credentials) -> None:
     with Connector(credentials=fake_credentials) as connector:
         # try to connect using unsupported driver, should raise KeyError