feat(cloud-sql): enable lazy refresh for postgres, mysql and sql server connectors (#13146)

Enable lazy refresh for the Python Cloud SQL connector (Postgres, MySQL, and SQL Server).

Author: kgala2

cloud-sql/mysql/sqlalchemy/connect_connector.py

@@ -41,7 +41,8 @@ def connect_with_connector() -> sqlalchemy.engine.base.Engine:
 
     ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC
 
-    connector = Connector(ip_type)
+    # initialize Cloud SQL Python Connector object
+    connector = Connector(ip_type=ip_type, refresh_strategy="LAZY")
 
     def getconn() -> pymysql.connections.Connection:
         conn: pymysql.connections.Connection = connector.connect(

cloud-sql/mysql/sqlalchemy/connect_connector_auto_iam_authn.py

@@ -40,7 +40,7 @@ def connect_with_connector_auto_iam_authn() -> sqlalchemy.engine.base.Engine:
     ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC
 
     # initialize Cloud SQL Python Connector object
-    connector = Connector()
+    connector = Connector(refresh_strategy="LAZY")
 
     def getconn() -> pymysql.connections.Connection:
         conn: pymysql.connections.Connection = connector.connect(

cloud-sql/postgres/sqlalchemy/connect_connector.py

@@ -42,7 +42,7 @@ def connect_with_connector() -> sqlalchemy.engine.base.Engine:
     ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC
 
     # initialize Cloud SQL Python Connector object
-    connector = Connector()
+    connector = Connector(refresh_strategy="LAZY")
 
     def getconn() -> pg8000.dbapi.Connection:
         conn: pg8000.dbapi.Connection = connector.connect(

cloud-sql/postgres/sqlalchemy/connect_connector_auto_iam_authn.py

@@ -40,7 +40,7 @@ def connect_with_connector_auto_iam_authn() -> sqlalchemy.engine.base.Engine:
     ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC
 
     # initialize Cloud SQL Python Connector object
-    connector = Connector()
+    connector = Connector(refresh_strategy="LAZY")
 
     def getconn() -> pg8000.dbapi.Connection:
         conn: pg8000.dbapi.Connection = connector.connect(

cloud-sql/sql-server/sqlalchemy/connect_connector.py

@@ -41,7 +41,8 @@ def connect_with_connector() -> sqlalchemy.engine.base.Engine:
 
     ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC
 
-    connector = Connector(ip_type)
+    # initialize Cloud SQL Python Connector object
+    connector = Connector(ip_type=ip_type, refresh_strategy="LAZY")
 
     connect_args = {}
     # If your SQL Server instance requires SSL, you need to download the CA