Installing seaborn on Docker Alpine - numpy

Question

I am trying to install seaborn with this Dockerfile:
FROM alpine:latest
RUN apk add --update python py-pip python-dev
RUN pip install seaborn
CMD python
The error I get is related to numpy and scipy (required by seaborn). It starts with:
/tmp/easy_install-nvj61E/numpy-1.11.1/setup.py:327: UserWarning:
Unrecognized setuptools command, proceeding with generating Cython
sources and expanding templates
and ends with
File "numpy/core/setup.py", line 654, in get_mathlib_info
RuntimeError: Broken toolchain: cannot link a simple C program
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-DZ4cXr/scipy/
The command '/bin/sh -c pip install seaborn' returned a non-zero code: 1
Any idea how I can fix this?

Answer 1

To fix this error, you need to install gcc: apk add gcc.
But you will see that you will hit a new error as numpy, matplotlip and scipy have several dependencies. You need to also install gfortran, musl-dev, freetype-dev, etc.
Here is a Dockerfile based on you initial one that will install those dependencies as well as seaborn:
FROM alpine:latest
# install dependencies
# the lapack package is only in the community repository
RUN echo "http://dl-4.alpinelinux.org/alpine/edge/community" >> /etc/apk/repositories
RUN apk --update add --no-cache \
lapack-dev \
gcc \
freetype-dev
RUN apk add python py-pip python-dev
# Install dependencies
RUN apk add --no-cache --virtual .build-deps \
gfortran \
musl-dev \
g++
RUN ln -s /usr/include/locale.h /usr/include/xlocale.h
RUN pip install seaborn
# removing dependencies
RUN apk del .build-deps
CMD python
You'll notice that I'm removing the dependencies using apk-del .build-deps to limit the size of your image (http://www.sandtable.com/reduce-docker-image-sizes-using-alpine/).
Personally I also had to install ca-certificates but it seems you didn't have this issue.
Note: You could also build your image FROM the python:2.7-alpine image to avoid installing python and pip yourself.