Alpine ERROR: unsatisfiable constraints: py3-pandas (missing): - docker

Question

I have the following dockerfile:
FROM alpine:latest
ADD crontab.txt /crontab.txt
ADD script.sh /script.sh
COPY entry.sh /entry.sh
ADD app /app
RUN chmod 755 /script.sh /entry.sh
RUN /usr/bin/crontab /crontab.txt
# install dependencies
# the lapack package is only in the community repository
RUN echo "http://dl-8.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories \
&& apk update \
&& apk add --no-cache python3 py-pip py3-setuptools python-dev py3-lxml py3-requests py3-numpy py3-cssselect py3-pandas
RUN apk --update add --no-cache \
lapack-dev \
gcc \
freetype-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 pip3 install cython
RUN pip3 install pymongo xlrd
CMD ["/entry.sh"]
when I try to build the dockerfile, I received the error saying that py3-pandas (missing).
I am wondering whether that's the Alpine package management issue.

Answer 1

I can reproduce your issue by doing just:
FROM alpine:latest
RUN echo "http://dl-8.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories \
&& apk update \
&& apk add --no-cache py3-pandas
Some comments here:
If you are going to use the edge/testing packages repository already, then you would be better using the alpine:edge image, although I would not advise this for a production server, of course
Using another package repository than the default one on apk can be done on a one run basis using the option
-X, --repository REPO Use packages from REPO
From apk --help
The package python-dev does not exist in the edge/testing repository, you should use python3-dev
Important disclaimer: this solution does involve using the testing repository and the edge rolling release branch of Alpine, and is thus not recommended for production use.
So, in the end, all your dependencies can be installed doing:
FROM alpine:edge
RUN apk add --no-cache --repository http://dl-cdn.alpinelinux.org/alpine/edge/testing \
py-pip \
py3-setuptools \
python3-dev \
py3-lxml \
py3-requests \
py3-numpy \
py3-cssselect \
py3-pandas \
lapack-dev \
gcc \
freetype-dev
Note that I didn't add the build dependancies there, as they don't seems to be related to your issue at hand

Answer 2

Don't use alpine images for python; there's too many issues. Use a something like python:slim-buster. You can then just install your requirements with:
FROM python:3.8.4-slim-buster
COPY ./requirements.txt /requirements.txt
RUN pip install -r /requirements.txt