Docker部署FASTAPI连接PlanetScale MySQL遇SSL错误求助

容器构建与运行正常，浏览器可正常访问FastAPI应用，但调用API连接PlanetScale托管的MySQL数据库时，抛出以下错误：

MySQLdb.OperationalError: (2026, 'SSL connection error: unknown error number')

我的Dockerfile内容如下：

FROM python:3.6.4
#WORKDIR /etc/ssl/
#add /etc/ssl/certs:/etc/ssl/certs:ro
RUN mkdir /apis
#RUN mkdir /etc
#RUN mkdir /etc/ssl
WORKDIR /apis
COPY requirements.txt .
COPY main.py .
COPY prod.env .
COPY cert.pem /etc/ssl/
RUN  python -m pip install --upgrade pip
#RUN  pip install -r requirements.txt
RUN  pip install "fastapi[all]"
RUN  pip install mysql
RUN  pip install mysqlclient
RUN  pip install python-dotenv
RUN  pip install PyMySQL
COPY . .
#CMD yum update ca-certificates
# THE BELOW SECTION IS POPULATED WITH THE CORRECT SETTINGS.
ENV HOST=<>\
ENV USERNAME=<>\
ENV PASSWORD=<>\
ENV DATABASE=<>\

RUN echo "Host: $HOST"
RUN echo "Username: $USERNAME"
RUN echo "Password: $PASSWORD"
RUN echo "Database: $DATABASE"
#RUN cd /etc/ssl/
#COPY /etc/ssl/ .
CMD ["uvicorn", "main:app", "--host=0.0.0.0", "--port=80"]

恳请各位提供解决思路。

内容的提问来源于stack exchange，提问作者Brandon Michael Hunter