Dockerfile

FROM buildpack-deps:buster

# ensure local python is preferred over distribution python
ENV PATH /usr/local/bin:$PATH

# http://bugs.python.org/issue19846
# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
ENV LANG C.UTF-8
# https://github.com/docker-library/python/issues/147
ENV PYTHONIOENCODING UTF-8

# extra dependencies (over what buildpack-deps already includes)
RUN apt-get update && apt-get install -y --no-install-recommends \
		tk-dev \
	&& rm -rf /var/lib/apt/lists/*

ENV GPG_KEY C01E1CAD5EA2C4F0B8E3571504C367C218ADD4FF
ENV PYTHON_VERSION 2.7.18

RUN set -ex \
	\
	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
	&& export GNUPGHOME="$(mktemp -d)" \
	&& gpg --batch --keyserver ha.pool.sks-keyservers.net --recv-keys "$GPG_KEY" \
	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
	&& { command -v gpgconf > /dev/null && gpgconf --kill all || :; } \
	&& rm -rf "$GNUPGHOME" python.tar.xz.asc \
	&& mkdir -p /usr/src/python \
	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
	&& rm python.tar.xz \
	\
	&& cd /usr/src/python \
	&& gnuArch="$(dpkg-architecture --query DEB_BUILD_GNU_TYPE)" \
	&& ./configure \
		--build="$gnuArch" \
		--enable-optimizations \
		--enable-option-checking=fatal \
		--enable-shared \
		--enable-unicode=ucs4 \
	&& make -j "$(nproc)" \
# setting PROFILE_TASK makes "--enable-optimizations" reasonable: https://bugs.python.org/issue36044 / https://github.com/docker-library/python/issues/160#issuecomment-509426916
		PROFILE_TASK='-m test.regrtest --pgo \
			test_array \
			test_base64 \
			test_binascii \
			test_binhex \
			test_binop \
			test_bytes \
			test_c_locale_coercion \
			test_class \
			test_cmath \
			test_codecs \
			test_compile \
			test_complex \
			test_csv \
			test_decimal \
			test_dict \
			test_float \
			test_fstring \
			test_hashlib \
			test_io \
			test_iter \
			test_json \
			test_long \
			test_math \
			test_memoryview \
			test_pickle \
			test_re \
			test_set \
			test_slice \
			test_struct \
			test_threading \
			test_time \
			test_traceback \
			test_unicode \
		' \
	&& make install \
	&& ldconfig \
	\
	&& find /usr/local -depth \
		\( \
			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
			-o \
			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
		\) -exec rm -rf '{}' + \
	&& rm -rf /usr/src/python \
	\
	&& python --version

# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
ENV PYTHON_PIP_VERSION 20.0.2
# https://github.com/pypa/get-pip
ENV PYTHON_GET_PIP_URL https://github.com/pypa/get-pip/raw/d59197a3c169cef378a22428a3fa99d33e080a5d/get-pip.py
ENV PYTHON_GET_PIP_SHA256 421ac1d44c0cf9730a088e337867d974b91bdce4ea2636099275071878cc189e

RUN set -ex; \
	\
	wget -O get-pip.py "$PYTHON_GET_PIP_URL"; \
	echo "$PYTHON_GET_PIP_SHA256 *get-pip.py" | sha256sum --check --strict -; \
	\
	python get-pip.py \
		--disable-pip-version-check \
		--no-cache-dir \
		"pip==$PYTHON_PIP_VERSION" \
	; \
	pip --version; \
	\
	find /usr/local -depth \
		\( \
			\( -type d -a \( -name test -o -name tests -o -name idle_test \) \) \
			-o \
			\( -type f -a \( -name '*.pyc' -o -name '*.pyo' \) \) \
		\) -exec rm -rf '{}' +; \
	rm -f get-pip.py

# install "virtualenv", since the vast majority of users of this image will want it
RUN pip install --no-cache-dir virtualenv

CMD ["python2.7"]