Dockerfile

ARG FROM_IMAGE=python:slim
FROM $FROM_IMAGE
LABEL maintainer "Praekelt.org <sre@praekelt.org>"

# pip: Disable cache and use Praekelt.org Python Package Index
RUN set -ex; \
    codename="$(. /etc/os-release; echo $VERSION | grep -oE [a-z]+)"; \
    echo '[global]' > /etc/pip.conf; \
# `no-cache-dir = false` is not intuitive--it's translated to a CLI option and does disable the cache
    echo 'no-cache-dir = false' >> /etc/pip.conf; \
    echo "extra-index-url = https://$codename.wheelhouse.praekelt.org/simple" >> /etc/pip.conf

# HACK: Make sure a Python is available as `python`. Only necessary for PyPy.
RUN set -ex; \
    if ! command -v python > /dev/null; then \
        cd /usr/local/bin; \
        for py in pypy3 pypy python3 python2; do \
            [ -x "$py" ] && ln -s "$py" python || true; \
        done; \
        readlink -e python; \
    fi

# Install utility scripts
COPY scripts /scripts
ENV PATH $PATH:/scripts

# Install gosu/dumb-init after copying in the scripts so we can use them
# Note that gosu/dumb-init are only available from Debian Stretch, tini should
# be available on Buster.
RUN set -xe; \
    apt-get-install.sh dumb-init gosu; \
# Link `gosu` as `su-exec` for compatibility with Alpine Linux
    ln -s "$(which gosu)" /usr/local/sbin/su-exec; \
    gosu nobody true; \
# Link `dumb-init` as `dinit` and `tini` for compatibility with older images
    ln -s "$(which dumb-init)" /usr/local/sbin/dinit; \
    dinit -- true; \
    ln -s "$(which dumb-init)" /usr/local/sbin/tini; \
    tini -- true

# Set tini as the default entrypoint
ENTRYPOINT ["tini", "--"]
CMD ["python"]