From 9f061ea97d5927b884474d6a08115f40b7d11707 Mon Sep 17 00:00:00 2001 From: powderluv Date: Tue, 30 Aug 2022 11:07:25 -0700 Subject: [PATCH] Dockerize CI + Release builds (#1234) Gets both CI and Release builds integrated in one workflow. Mount ccache and pip cache as required for fast iterative builds Current Release docker builds still run with root perms, fix it in the future to run as the same user. There may be some corner cases left especially when switching build types etc. Docker build TEST plan: tl;dr: Build everythin: Releases (Python 3.8, 3.9, 3.10) and CIs. TM_PACKAGES="torch-mlir out-of-tree in-tree" 2.57s user 2.49s system 0% cpu 30:33.11 total Out of Tree + PyTorch binaries: Fresh build (purged cache): TM_PACKAGES="out-of-tree" 0.47s user 0.51s system 0% cpu 5:24.99 total Incremental with ccache: TM_PACKAGES="out-of-tree" 0.09s user 0.08s system 0% cpu 34.817 total Out of Tree + PyTorch from source Incremental TM_PACKAGES="out-of-tree" TM_USE_PYTORCH_BINARY=OFF 1.58s user 1.81s system 2% cpu 1:59.61 total In-Tree + PyTorch binaries: Fresh build and tests: (purge ccache) TM_PACKAGES="in-tree" 0.53s user 0.49s system 0% cpu 6:23.35 total Fresh build/ but with prior ccache TM_PACKAGES="in-tree" 0.45s user 0.66s system 0% cpu 3:57.47 total Incremental in-tree with all tests and regression tests TM_PACKAGES="in-tree" 0.16s user 0.09s system 0% cpu 2:18.52 total In-Tree + PyTorch from source Fresh build and tests: (purge ccache) TM_PACKAGES="in-tree" TM_USE_PYTORCH_BINARY=OFF 2.03s user 2.28s system 0% cpu 11:11.86 total Fresh build/ but with prior ccache TM_PACKAGES="in-tree" TM_USE_PYTORCH_BINARY=OFF 1.58s user 1.88s system 1% cpu 4:53.15 total Incremental in-tree with all tests and regression tests TM_PACKAGES="in-tree" TM_USE_PYTORCH_BINARY=OFF 1.09s user 1.10s system 1% cpu 3:29.84 total Incremental without tests TM_PACKAGES="in-tree" TM_USE_PYTORCH_BINARY=OFF TM_SKIP_TESTS=ON 1.52s user 1.42s system 3% cpu 1:15.82 total In-tree+out-of-tree + Pytorch Binaries TM_PACKAGES="out-of-tree in-tree" 0.25s user 0.18s system 0% cpu 3:01.91 total To clear all artifacts: rm -rf build build_oot llvm-build libtorch docker_venv externals/pytorch/build --- .gitignore | 6 + build_tools/docker/Dockerfile | 54 ++++ .../python_deploy/build_linux_packages.sh | 240 +++++++++++++++--- docs/development.md | 115 +++++++++ 4 files changed, 385 insertions(+), 30 deletions(-) create mode 100644 build_tools/docker/Dockerfile diff --git a/.gitignore b/.gitignore index 543d617fe..330a871b0 100644 --- a/.gitignore +++ b/.gitignore @@ -1,6 +1,7 @@ *.swp .cache/ .vscode +.ccache .env *.code-workspace .ipynb_checkpoints @@ -26,3 +27,8 @@ bazel-* # Autogenerated files /python/torch_mlir/csrc/base_lazy_backend/generated + +#Docker builds +build_oot/ +docker_venv/ +llvm-build/ diff --git a/build_tools/docker/Dockerfile b/build_tools/docker/Dockerfile new file mode 100644 index 000000000..1027a1141 --- /dev/null +++ b/build_tools/docker/Dockerfile @@ -0,0 +1,54 @@ +ARG BASE_IMG=ubuntu:22.04 +FROM ${BASE_IMG} as dev-base + +# Disable apt-key parse waring. If someone knows how to do whatever the "proper" +# thing is then feel free. The warning complains about parsing apt-key output, +# which we're not even doing. +ARG APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 + +ARG ARCH="x86_64" +ARG REPO_NAME="deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy main" +RUN apt-get update && \ + apt-get install -y \ + ca-certificates \ + software-properties-common \ + wget \ + apt-transport-https \ + ccache \ + curl \ + cmake \ + ninja-build \ + git \ + gnupg \ + lsb-release \ + python3-pip \ + python3.10 \ + python3.10-dev \ + python3.10-venv \ + unzip && \ + echo $REPO_NAME >> /etc/apt/sources.list.d/llvm.list && \ + wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key| apt-key add - && \ + apt-get update && \ + apt-get install -y \ + clang \ + lld + +######## Bazel ######## +WORKDIR /install-bazel +ARG BAZEL_VERSION=5.2.0 + +# https://bazel.build/install/ubuntu +RUN curl -fsSL https://bazel.build/bazel-release.pub.gpg \ + | gpg --dearmor >bazel-archive-keyring.gpg \ + && mv bazel-archive-keyring.gpg /usr/share/keyrings \ + && echo "deb [arch=amd64 signed-by=/usr/share/keyrings/bazel-archive-keyring.gpg] https://storage.googleapis.com/bazel-apt stable jdk1.8" \ + | tee /etc/apt/sources.list.d/bazel.list \ + && apt-get update \ + && apt-get install -y "bazel=${BAZEL_VERSION?}" \ + && rm -rf /install-bazel + +### Clean up +RUN apt-get clean \ + && rm -rf /var/lib/apt/lists/* + +WORKDIR /main_checkout/torch-mlir diff --git a/build_tools/python_deploy/build_linux_packages.sh b/build_tools/python_deploy/build_linux_packages.sh index 887b4c8e8..44ab910c0 100755 --- a/build_tools/python_deploy/build_linux_packages.sh +++ b/build_tools/python_deploy/build_linux_packages.sh @@ -16,22 +16,21 @@ # ./build_tools/python_deploy/build_linux_packages.sh # # Build specific Python versions and packages to custom directory: -# python_versions="cp38-cp38 cp39-cp39" \ -# packages="torch-mlir" \ -# output_dir="/tmp/wheelhouse" \ +# TM_PYTHON_VERSIONS="cp38-cp38 cp39-cp39" \ +# TM_PACKAGES="torch-mlir" \ +# TM_OUTPUT_DIR="/tmp/wheelhouse" \ # ./build_tools/python_deploy/build_linux_packages.sh # # Valid Python versions match a subdirectory under /opt/python in the docker # image. Typically: -# cp37-cp37m cp38-cp38 cp39-cp39 cp310-cp310 +# cp38-cp38 cp39-cp39 cp310-cp310 # # Valid packages: -# torch-mlir +# torch-mlir, in-tree, out-of-tree # # Note that this script is meant to be run on CI and it will pollute both the -# output directory and in-tree build/ directories (under runtime/ and -# iree/compiler/) with docker created, root owned builds. Sorry - there is -# no good way around it. +# output directory and in-tree build/ directories with docker created, root owned builds. +# Sorry - there is no good way around it but TODO: move to using user UID/GID. # # It can be run on a workstation but recommend using a git worktree dedicated # to packaging to avoid stomping on development artifacts. @@ -39,54 +38,117 @@ set -eu -o errtrace this_dir="$(cd "$(dirname "$0")" && pwd)" repo_root="$(cd "$this_dir"/../../ && pwd)" -manylinux_docker_image="${manylinux_docker_image:-stellaraccident/manylinux2014_x86_64-bazel-5.1.0:latest}" -python_versions="${TM_PYTHON_VERSIONS:-cp38-cp38 cp39-cp39 cp310-cp310}" -output_dir="${output_dir:-${this_dir}/wheelhouse}" -packages="${packages:-torch-mlir}" +# This needs to be a manylinux image so we can ship pip packages +TM_RELEASE_DOCKER_IMAGE="${TM_RELEASE_DOCKER_IMAGE:-stellaraccident/manylinux2014_x86_64-bazel-5.1.0:latest}" +# This assumes an Ubuntu LTS like image. You can build your own with +# ./build_tools/docker/Dockerfile +TM_CI_DOCKER_IMAGE="${TM_CI_DOCKER_IMAGE:-powderluv/torch-mlir-ci:latest}" +# Version of Python to use in Release builds. Ignored in CIs. +TM_PYTHON_VERSIONS="${TM_PYTHON_VERSIONS:-cp38-cp38 cp39-cp39 cp310-cp310}" +# Location to store Release wheels +TM_OUTPUT_DIR="${TM_OUTPUT_DIR:-${this_dir}/wheelhouse}" +# What "packages to build" +TM_PACKAGES="${TM_PACKAGES:-torch-mlir out-of-tree in-tree}" +# Use pre-built Pytorch +TM_USE_PYTORCH_BINARY="${TM_USE_PYTORCH_BINARY:-ON}" +# Skip running tests if you want quick iteration +TM_SKIP_TESTS="${TM_SKIP_TESTS:-OFF}" PKG_VER_FILE="${repo_root}"/torch_mlir_package_version ; [ -f "$PKG_VER_FILE" ] && . "$PKG_VER_FILE" export TORCH_MLIR_PYTHON_PACKAGE_VERSION="${TORCH_MLIR_PYTHON_PACKAGE_VERSION:-0.0.1}" echo "Setting torch-mlir Python Package version to: ${TORCH_MLIR_PYTHON_PACKAGE_VERSION}" function run_on_host() { - echo "Running on host" - echo "Launching docker image ${manylinux_docker_image}" - echo "Outputting to ${output_dir}" - rm -rf "${output_dir}" - mkdir -p "${output_dir}" + echo "Running on host for $1:$@" + echo "Outputting to ${TM_OUTPUT_DIR}" + rm -rf "${TM_OUTPUT_DIR}" + mkdir -p "${TM_OUTPUT_DIR}" + case "$package" in + torch-mlir) + TM_CURRENT_DOCKER_IMAGE=${TM_RELEASE_DOCKER_IMAGE} + export USERID=0 + export GROUPID=0 + ;; + out-of-tree) + TM_CURRENT_DOCKER_IMAGE=${TM_CI_DOCKER_IMAGE} + # CI uses only Python3.10 + TM_PYTHON_VERSIONS="cp310-cp310" + export USERID=$(id -u) + export GROUPID=$(id -g) + ;; + in-tree) + TM_CURRENT_DOCKER_IMAGE=${TM_CI_DOCKER_IMAGE} + # CI uses only Python3.10 + TM_PYTHON_VERSIONS="cp310-cp310" + export USERID=$(id -u) + export GROUPID=$(id -g) + ;; + *) + echo "Unrecognized package '$package'" + exit 1 + ;; + esac + echo "Launching docker image ${TM_CURRENT_DOCKER_IMAGE} with UID:${USERID} GID:${GROUPID}" docker run --rm \ -v "${repo_root}:/main_checkout/torch-mlir" \ - -v "${output_dir}:/wheelhouse" \ + -v "${TM_OUTPUT_DIR}:/wheelhouse" \ + -v "${HOME}:/home/${USER}" \ + --user ${USERID}:${GROUPID} \ + --workdir="/home/$USER" \ + --volume="/etc/group:/etc/group:ro" \ + --volume="/etc/passwd:/etc/passwd:ro" \ + --volume="/etc/shadow:/etc/shadow:ro" \ + --ipc=host \ + --ulimit nofile=32768:32768 \ -e __MANYLINUX_BUILD_WHEELS_IN_DOCKER=1 \ -e "TORCH_MLIR_PYTHON_PACKAGE_VERSION=${TORCH_MLIR_PYTHON_PACKAGE_VERSION}" \ - -e "python_versions=${python_versions}" \ - -e "packages=${packages}" \ - "${manylinux_docker_image}" \ - -- bash /main_checkout/torch-mlir/build_tools/python_deploy/build_linux_packages.sh + -e "TM_PYTHON_VERSIONS=${TM_PYTHON_VERSIONS}" \ + -e "TM_PACKAGES=${package}" \ + -e "TM_SKIP_TESTS=${TM_SKIP_TESTS}" \ + -e "TM_USE_PYTORCH_BINARY=${TM_USE_PYTORCH_BINARY}" \ + -e "CCACHE_DIR=/main_checkout/torch-mlir/.ccache" \ + "${TM_CURRENT_DOCKER_IMAGE}" \ + /bin/bash /main_checkout/torch-mlir/build_tools/python_deploy/build_linux_packages.sh } function run_in_docker() { echo "Running in docker" - echo "Using python versions: ${python_versions}" + echo "Using python versions: ${TM_PYTHON_VERSIONS}" local orig_path="$PATH" # Build phase. - for package in $packages; do - echo "******************** BUILDING PACKAGE ${package} ********************" - for python_version in $python_versions; do + for package in $TM_PACKAGES; do + echo "******************** BUILDING PACKAGE ${package} (docker) ************" + for python_version in $TM_PYTHON_VERSIONS; do python_dir="/opt/python/$python_version" if ! [ -x "$python_dir/bin/python" ]; then - echo "ERROR: Could not find python: $python_dir (skipping)" - continue + echo "Could not find python: $python_dir (using system default Python3)" + python_dir=`which python3` + echo "Defaulting to $python_dir (expected for CI builds)" fi export PATH=$python_dir/bin:$orig_path - echo ":::: Python version $(python --version)" + echo ":::: Python version $(python3 --version)" case "$package" in torch-mlir) clean_wheels torch_mlir "$python_version" build_torch_mlir #run_audit_wheel torch_mlir "$python_version" + clean_build torch_mlir "$python_version" + ;; + out-of-tree) + setup_venv "$python_version" + build_out_of_tree "$TM_USE_PYTORCH_BINARY" "$python_version" + if [ "${TM_SKIP_TESTS}" == "OFF" ]; then + test_out_of_tree + fi + ;; + in-tree) + setup_venv "$python_version" + build_in_tree "$TM_USE_PYTORCH_BINARY" "$python_version" + if [ "${TM_SKIP_TESTS}" == "OFF" ]; then + test_in_tree; + fi ;; *) echo "Unrecognized package '$package'" @@ -97,6 +159,121 @@ function run_in_docker() { done } + +function build_in_tree() { + local torch_from_src="$1" + local python_version="$2" + echo ":::: Build in-tree Torch from source: $torch_from_src with Python: $python_version" + cmake -GNinja -B/main_checkout/torch-mlir/build \ + -DCMAKE_BUILD_TYPE=Release \ + -DCMAKE_C_COMPILER=clang \ + -DCMAKE_CXX_COMPILER=clang++ \ + -DCMAKE_LINKER=lld \ + -DLLVM_ENABLE_ASSERTIONS=ON \ + -DCMAKE_C_COMPILER_LAUNCHER=ccache \ + -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \ + -DLLVM_ENABLE_PROJECTS=mlir \ + -DLLVM_EXTERNAL_PROJECTS="torch-mlir;torch-mlir-dialects" \ + -DLLVM_EXTERNAL_TORCH_MLIR_SOURCE_DIR="/main_checkout/torch-mlir" \ + -DLLVM_EXTERNAL_TORCH_MLIR_DIALECTS_SOURCE_DIR="/main_checkout/torch-mlir/externals/llvm-external-projects/torch-mlir-dialects" \ + -DLLVM_TARGETS_TO_BUILD=host \ + -DMLIR_ENABLE_BINDINGS_PYTHON=ON \ + -DTORCH_MLIR_ENABLE_LTC=OFF \ + -DTORCH_MLIR_USE_INSTALLED_PYTORCH="$torch_from_src" \ + -DPython3_EXECUTABLE="$(which python3)" \ + /main_checkout/torch-mlir/externals/llvm-project/llvm + cmake --build /main_checkout/torch-mlir/build + ccache -s +} + +function test_in_tree() { + echo ":::: Test in-tree" + cmake --build /main_checkout/torch-mlir/build --target check-torch-mlir-all + + cd /main_checkout/torch-mlir/ + export PYTHONPATH="/main_checkout/torch-mlir/build/tools/torch-mlir/python_packages/torch_mlir" + + echo ":::: Run refbackend e2e integration tests" + python -m e2e_testing.main --config=refbackend -v + + echo ":::: Run eager_mode e2e integration tests" + python -m e2e_testing.main --config=eager_mode -v + + echo ":::: Run TOSA e2e integration tests" + python -m e2e_testing.main --config=tosa -v + + echo ":::: Run Lazy Tensor Core e2e integration tests" + # Temporarily disabled in top of main (https://github.com/llvm/torch-mlir/pull/1292) + #python -m e2e_testing.torchscript.main --config=lazy_tensor_core -v +} + +function setup_venv() { + local python_version="$1" + echo ":::: Setting up VENV with Python: $python_version" + python3 -m venv /main_checkout/torch-mlir/docker_venv + source /main_checkout/torch-mlir/docker_venv/bin/activate + + echo ":::: pip installing dependencies" + python3 -m pip install -r /main_checkout/torch-mlir/externals/llvm-project/mlir/python/requirements.txt + python3 -m pip install -r /main_checkout/torch-mlir/requirements.txt + +} + +function build_out_of_tree() { + local torch_from_src="$1" + local python_version="$2" + echo ":::: Build out-of-tree Torch from source: $torch_from_src with Python: $python_version" + + if [ ! -d "/main_checkout/torch-mlir/llvm-build/lib/cmake/mlir/" ] + then + echo ":::: LLVM / MLIR is not built so building it first.." + cmake -GNinja -B/main_checkout/torch-mlir/llvm-build \ + -DCMAKE_BUILD_TYPE=Release \ + -DCMAKE_C_COMPILER=clang \ + -DCMAKE_CXX_COMPILER=clang++ \ + -DCMAKE_C_COMPILER_LAUNCHER=ccache \ + -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \ + -DCMAKE_LINKER=lld \ + -DLLVM_ENABLE_ASSERTIONS=ON \ + -DLLVM_ENABLE_PROJECTS=mlir \ + -DLLVM_TARGETS_TO_BUILD=host \ + -DMLIR_ENABLE_BINDINGS_PYTHON=ON \ + -DPython3_EXECUTABLE="$(which python3)" \ + /main_checkout/torch-mlir/externals/llvm-project/llvm + cmake --build /main_checkout/torch-mlir/llvm-build + fi + + # Incremental builds come here directly and can run cmake if required. + cmake -GNinja -B/main_checkout/torch-mlir/build_oot \ + -DCMAKE_C_COMPILER=clang \ + -DCMAKE_CXX_COMPILER=clang++ \ + -DCMAKE_C_COMPILER_LAUNCHER=ccache \ + -DCMAKE_CXX_COMPILER_LAUNCHER=ccache \ + -DCMAKE_LINKER=lld \ + -DLLVM_DIR="/main_checkout/torch-mlir/llvm-build/lib/cmake/llvm/" \ + -DMLIR_DIR="/main_checkout/torch-mlir/llvm-build/lib/cmake/mlir/" \ + -DMLIR_ENABLE_BINDINGS_PYTHON=OFF \ + -DTORCH_MLIR_ENABLE_LTC=OFF \ + -DTORCH_MLIR_USE_INSTALLED_PYTORCH="$torch_from_src" \ + -DPython3_EXECUTABLE="$(which python3)" \ + /main_checkout/torch-mlir + cmake --build /main_checkout/torch-mlir/build_oot + ccache -s +} + +function test_out_of_tree() { + echo ":::: Test out-of-tree" + cmake --build /main_checkout/torch-mlir/build_oot --target check-torch-mlir-all +} + +function clean_build() { + # clean up for recursive runs + local package="$1" + local python_version="$2" + echo ":::: Clean build dir $package $python_version" + rm -rf /main_checkout/torch-mlir/build /main_checkout/torch-mlir/llvm-build /main_checkout/torch-mlir/docker_venv /main_checkout/torch-mlir/libtorch +} + function build_torch_mlir() { python -m pip install -r /main_checkout/torch-mlir/requirements.txt --extra-index-url https://download.pytorch.org/whl/nightly/cpu CMAKE_GENERATOR=Ninja \ @@ -123,7 +300,10 @@ function clean_wheels() { # Trampoline to the docker container if running on the host. if [ -z "${__MANYLINUX_BUILD_WHEELS_IN_DOCKER-}" ]; then - run_on_host "$@" + for package in $TM_PACKAGES; do + echo "******************** BUILDING PACKAGE ${package} (host) *************" + run_on_host "${package} $@" + done else run_in_docker "$@" fi diff --git a/docs/development.md b/docs/development.md index 231b9aba9..46bdb9c56 100644 --- a/docs/development.md +++ b/docs/development.md @@ -22,6 +22,121 @@ python -m pip install --upgrade pip python -m pip install -r requirements.txt ``` +## Docker Builds + +We have preliminary support for building with Docker images. This is a new +flow and we would like your feedback on how it works for you and please +feel free to file any feedback or issues. + +Install [Docker Engine](https://docs.docker.com/engine/install/ubuntu/). You don't need Docker Desktop. + +You have three types of builds selectable with the Environment Variable `TM_PACKAGES`:`torch-mlir` the +Release build, `out-of-tree` where torch-mlir is build with a pre-built MLIR and `in-tree` where torch-mlir +is built as part of the LLVM project along with MLIR. + +We mount a ccache and pip cache inside the docker container to speed up iterative builds. Iterative +builds should be as fast as running without docker. + +### In-Tree builds + +Build MLIR and Torch-MLIR together as part of the LLVM repo. + +```shell +TM_PACKAGES="in-tree" ./build_tools/python_deploy/build_linux_packages.sh +``` + +### Out-of-Tree builds + +Build LLVM/MLIR first and then build Torch-MLIR referencing that build +```shell +TM_PACKAGES="out-of-tree" ./build_tools/python_deploy/build_linux_packages.sh +``` + +### Release builds + +Build in a manylinux Docker image so we can upload artifacts to PyPI. + +```shell +TM_PACKAGES="torch-mlir" ./build_tools/python_deploy/build_linux_packages.sh +``` + +### Mimicing CI+Release builds + +If you wanted to build all the CIs locally + +```shell +TM_PACKAGES="out-of-tree in-tree" ./build_tools/python_deploy/build_linux_packages.sh +``` + +If you wanted to build all the CIs and the Release builds (just with Python 3.10 since most other Python builds are redundant) + +```shell +TM_PACKAGES="torch-mlir out-of-tree in-tree" TM_PYTHON_VERSIONS="cp310-cp310" ./build_tools/python_deploy/build_linux_packages.sh +``` + +Note: The Release docker still runs as root so it may generate some files owned by root:root. We hope to move it to run as a user in the future. + +### Cleaning up + +Docker builds tend to leave a wide variety of files around. Luckily most are owned by the user but there are still some that need to be removed +as superuser. + +```shell +rm -rf build build_oot llvm-build docker_venv externals/pytorch/build .ccache +``` + +## Building your own Docker image + +If you would like to build your own docker image (usually not necessary). You can run: + +```shell +cd ./build_tools/docker +docker build -t your-name/torch-mlir-ci --no-cache . +``` + +### Other configurable environmental variables + +The following additional environmental variables can be used to customie your docker build: + +* Custom Release Docker image: + Defaults to `stellaraccident/manylinux2014_x86_64-bazel-5.1.0:latest` +```shell + TM_RELEASE_DOCKER_IMAGE="stellaraccident/manylinux2014_x86_64-bazel-5.1.0:latest" +``` +* Custom CI Docker image: + Defaults to `powderluv/torch-mlir-ci:latest`. This assumes an Ubuntu LTS like image. You can build your own with `./build_tools/docker/Dockerfile` +```shell + TM_CI_DOCKER_IMAGE="powderluv/torch-mlir-ci:latest" +``` + +* Custom Python Versions for Release builds: + Version of Python to use in Release builds. Ignored in CIs. Defaults to `cp38-cp38 cp39-cp39 cp310-cp310` +```shell + TM_PYTHON_VERSIONS="cp38-cp38 cp39-cp39 cp310-cp310" +``` + +* Location to store Release build wheels +```shell + TM_OUTPUT_DIR="./build_tools/python_deploy/wheelhouse" +``` + +* What "packages" to build: + Defaults to torch-mlir. Options are `torch-mlir out-of-tree in-tree` +```shell + TM_PACKAGES="torch-mlir out-of-tree in-tree" +``` +* Use pre-built Pytorch: + Defaults to using pre-built Pytorch. Setting it to `OFF` builds from source +```shell + TM_USE_PYTORCH_BINARY="OFF" +``` +* Skip running tests + Skip running tests if you want quick build only iteration. Default set to `OFF` +```shell + TM_SKIP_TESTS="OFF" +``` + + ## Build Python Packages We have preliminary support for building Python packages. This can be done