部署Flask_PyMongo至GCP App Engine时SSL握手失败求助

我是Eitan，刚接触Google Cloud与Flask-PyMongo。将应用部署至App Engine时，尽管已在MONGO_URI中指定本地pem文件至tlsCAFile属性，仍出现错误：pymongo.errors.ServerSelectionTimeoutError: SSL handshake failed。我尝试过certifi.where()、ssl=False、ssl_cert_reqs=CERT_NONE及将pem证书放入本地项目等方法，问题仍未解决。

以下是我的代码：

app.py #

from flask import Flask, render_template
from flask_pymongo import PyMongo, MongoClient
app = Flask(__name__)
# 注：密码没问题，只是不想泄露真实密码
app.config["MONGO_URI"] = "mongodb+srv://eitanbrochstein:password@cluster0.rhtkmvj.mongodb.net/Flask?authSource=admin&tlsCAFile=cacert.pem"
mongo = PyMongo(app)

@app.route("/")
def home():
    # #创建一条数据
    print(mongo.db.users.insert_one({"user": "Username"}))
    return render_template("index.html")

if __name__ == "__main__":
    app.run(debug=True)

app.yaml #

runtime: python
env: flex
entrypoint: gunicorn -b :8080 app:app

runtime_config:
    operating_system: "ubuntu22"
    runtime_version: "3.11"

requirements.txt #

Flask==2.1.3
Flask-PyMongo
certifi
dnspython
Werkzeug==2.2.2
gunicorn

内容的提问来源于stack exchange，提问作者Eitan Travels