fix: use lazy refresh for Cloud SQL Connector (#86)

Author: jackwotherspoon

pyproject.toml

@@ -13,7 +13,7 @@ dependencies = [
     "langchain-community>=0.0.18, <1.0.0",
     "numpy>=1.24.4, <2.0.0",
     "SQLAlchemy>=2.0.7, <3.0.0",
-    "cloud-sql-python-connector[pymysql]>=1.7.0, <2.0.0"
+    "cloud-sql-python-connector[pymysql]>=1.10.0, <2.0.0"
 ]
 
 classifiers = [

requirements.txt

@@ -3,5 +3,5 @@ langchain-community==0.2.0
 numpy===1.24.4; python_version <= "3.8"
 numpy==1.26.4; python_version > "3.8"
 SQLAlchemy==2.0.30
-cloud-sql-python-connector[pymysql]==1.9.2
+cloud-sql-python-connector[pymysql]==1.10.0
 

src/langchain_google_cloud_sql_mysql/engine.py

@@ -21,7 +21,7 @@
 import google.auth.transport.requests
 import requests
 import sqlalchemy
-from google.cloud.sql.connector import Connector
+from google.cloud.sql.connector import Connector, RefreshStrategy
 
 from .version import __version__
 
@@ -193,7 +193,9 @@ def _create_connector_engine(
             enable_iam_auth = True
 
         if cls._connector is None:
-            cls._connector = Connector(user_agent=USER_AGENT)
+            cls._connector = Connector(
+                user_agent=USER_AGENT, refresh_strategy=RefreshStrategy.LAZY
+            )
 
         # anonymous function to be used for SQLAlchemy 'creator' argument
         def getconn() -> pymysql.Connection: