error when docker build python django app in alpine linux - mysql

Question

Dockerfile
FROM python:3.6.5-alpine3.7
WORKDIR /app
ADD . /app
RUN pip install --no-cache-dir -r requirements.txt
EXPOSE 10021
CMD ["python", "manage.py", "runserver", "0.0.0.0:10021"]
Requirements
openpyxl==2.4.11
requests==2.18.4
Django==2.0.2
mysqlclient==1.3.12
Build Error
Collecting mysqlclient==1.3.12 (from -r requirements.txt (line 4))
Downloading https://mirrors.aliyun.com/pypi/packages/6f/86/bad31f1c1bb0cc99e88ca2adb7cb5c71f7a6540c1bb001480513de76a931/mysqlclient-1.3.12.tar.gz (89kB)
Complete output from command python setup.py egg_info:
/bin/sh: mysql_config: not found
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/tmp/pip-install-er3m_9t6/mysqlclient/setup.py", line 17, in <module>
metadata, options = get_config()
File "/tmp/pip-install-er3m_9t6/mysqlclient/setup_posix.py", line 44, in get_config
libs = mysql_config("libs_r")
File "/tmp/pip-install-er3m_9t6/mysqlclient/setup_posix.py", line 26, in mysql_config
raise EnvironmentError("%s not found" % (mysql_config.path,))
OSError: mysql_config not found
Thank #danblack for mariadb-connector-c-dev which helped me solve the OSError: mysql_config not found error.
New Dockerfile
FROM python:3.6.5-alpine3.7
WORKDIR /app
ADD . /app
RUN apk add --no-cache build-base && apk add --no-cache mariadb-connector-c-dev && pip install --no-cache-dir -r requirements.txt && apk del build-base
EXPOSE 10021
CMD ["python", "manage.py", "runserver", "0.0.0.0:10021"]
New Problem
But a new problem occurred, Docker printed nothing when docker run ... ran, no logs, no errors. It should have printed logs like the following
Performing system checks...
System check identified no issues (0 silenced).
September 04, 2018 - 15:56:26
Django version 2.0.2, using settings 'xxx.settings'
Starting development server at http://0.0.0.0:10021/
Quit the server with CTRL-BREAK.
Can someone show me a complete Dockerfile? Please help! Thank you so much.

Answer 1

You'd need to install the mariadb-connector-c-dev alpine package, which provides mysql_config that the python packages uses to identify which libraries it needs link against.

Answer 2

As per #danblack, 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

Answer 3

The trick is to temporarily install mariadb-dev which is only needed during build and then delete it. You can save some bandwitdh by installing the runtime deps before deleting the build deps.
Something like:
RUN apk add --no-cache --virtual .build-deps mariadb-dev ... \
&& pip install ...\
&& apk add --virtual .runtime-deps mariadb-client-libs \
&& apk del .build-deps

Answer 4

Since mysql_config is required to compile python mysql dependencies and also it has 127MB in size so keeping that in Docker container will increase container size to overcome this problem we can install and after successfully running pip install we can safely remove
apk add --no-cache mariadb-dev build-base
above command will install mysql dependencies then we can run pip install
pip3 install -r requirements.txt
once pip is done we can safely remove
apk del mariadb-dev build-base

Answer 5

In my case run with:
FROM python:3.8-alpine
RUN apk add mysql mysql-client gcc musl-dev mariadb-connector-c-dev
Adding mysql and mysql-client