Docker Alpine: Error loading MySQLdb module - mysql

Question

I am building an Alpine based image of a Django application with MariaDB and I can't figure out which dependency I should add to my Dockerfile so that my app could properly connect to the DB.
django.core.exceptions.ImproperlyConfigured: Error loading MySQLdb module.
Did you install mysqlclient?
Well, I thought I did. From what I read in this article, in this discussion, mariadb-dev is in Alpine the equivalent of default-libmysqlclient-dev in Debian based system. Furthermore, the mysql-client package in Alpine is merely a dummy package (containing mariadb-dev, mariadb-client, etc etc). Here is the Dockerfile:
# pull official base image
FROM python:3.7-alpine
# set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# set work directory
WORKDIR /usr/src/cms
# install mysqlclient
RUN apk update \
&& apk add --virtual build-deps gcc python3-dev musl-dev \
&& apk add --no-cache mariadb-dev\
&& apk del build-deps
# install dependencies
RUN pip install --upgrade pip
RUN pip install pipenv
COPY ./Pipfile /usr/src/cms/Pipfile
RUN pipenv install --skip-lock --system --dev
# copy entrypoint.sh
COPY ./entrypoint.sh /usr/src/cms/entrypoint.sh
# copy project
COPY . /usr/src/cms/
# run entrypoint.sh
ENTRYPOINT ["/usr/src/cms/entrypoint.sh"]
I tried to add mariadb-client, to use mysql-client instead.
I also tried to add RUN pip install django-mysql. Nothing seems to change. I successfully build Postgres Django apps without any problem but, when it comes to MySQl vs MariaDB // Debian vs Alpine, I feel confused. Any insight?

Answer 1

It seems you're missing the MySQLdb Python module, for which you should install the mysqlclient Python package: pip install mysqlclient.
On Alpine, pip will build mysqlclient from source, so you'll need gcc and musl-dev for this setup step, hence you'll need to postpone apk del build-deps to after Python modules are installed.
Fixed Dockerfile snippet:
RUN apk update \
&& apk add --virtual build-deps gcc python3-dev musl-dev \
&& apk add --no-cache mariadb-dev
...
RUN pip install mysqlclient
RUN apk del build-deps

Answer 2

Mainly you need to install mariadb-connector-c-dev package. But only this package will give compilation errors. So additionally you will need to add gcc and musl-dev packages into Dockerfile. This will make Django and MySQL work within alpine image.
FROM python:3.8-alpine
RUN apk add gcc musl-dev mariadb-connector-c-dev