Add Python binary build support for Heroku-24

This adds support for building Python binaries for Heroku-24
using GitHub Actions. Since the Heroku-24 base image supports
both `amd64` and `arm64` (to allow for multi-arch CNBs), for
Heroku-24 (only) we now also build binaries for both architectures.

A later PR will add support for Heroku-24 to the buildpack itself,
however, that depends on (a) the Python binaries already having
been built, (b) the Heroku build system for Heroku-24 being ready,
so those changes are not being made here.

GUS-W-15571102.

.github/workflows/build_python_runtime.yml

@@ -15,6 +15,7 @@ on:
           - auto
           - heroku-20
           - heroku-22
+          - heroku-24
         default: auto
         required: false
       dry_run:
@@ -67,3 +68,36 @@ jobs:
       - name: Upload Python runtime archive to S3
         if: (!inputs.dry_run)
         run: aws s3 sync ./upload "s3://${S3_BUCKET}"
+
+  heroku-24:
+    # On Heroku-24 we only support Python 3.12+.
+    if: inputs.stack == 'heroku-24' || (inputs.stack == 'auto' && startsWith(inputs.python_version,'3.12.'))
+    strategy:
+      fail-fast: false
+      matrix:
+        architecture: ["amd64", "arm64"]
+    runs-on: ${{ matrix.architecture == 'arm64' && 'pub-hk-ubuntu-22.04-arm-large' || 'pub-hk-ubuntu-22.04-xlarge' }}
+    env:
+      STACK_VERSION: "24"
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      # The beta Arm64 runners don't yet ship with the normal installed tools.
+      - name: Install Docker and AWS CLI (ARM64 only)
+        if: matrix.architecture == 'arm64'
+        run: |
+          sudo apt-get update --error-on=any
+          sudo apt-get install -y --no-install-recommends acl docker.io docker-buildx unzip
+          sudo usermod -aG docker $USER
+          sudo setfacl --modify user:$USER:rw /var/run/docker.sock
+          curl https://awscli.amazonaws.com/awscli-exe-linux-aarch64.zip -o awscliv2.zip
+          unzip awscliv2.zip
+          sudo ./aws/install
+          rm -rf awscliv2.zip ./aws/
+      - name: Build Docker image
+        run: docker build --platform="linux/${{ matrix.architecture }}" --pull --tag buildenv --build-arg=STACK_VERSION builds/
+      - name: Build and package Python runtime
+        run: docker run --rm --volume="${PWD}/upload:/tmp/upload" buildenv ./build_python_runtime.sh "${{ inputs.python_version }}"
+      - name: Upload Python runtime archive to S3
+        if: (!inputs.dry_run)
+        run: aws s3 sync ./upload "s3://${S3_BUCKET}"

builds/Dockerfile

@@ -1,9 +1,12 @@
-ARG STACK_VERSION="22"
+ARG STACK_VERSION="24"
 FROM heroku/heroku:${STACK_VERSION}-build
 
 ARG STACK_VERSION
 ENV STACK="heroku-${STACK_VERSION}"
 
+# For Heroku-24 and newer, the build image sets a non-root default `USER`.
+USER root
+
 RUN apt-get update --error-on=any \
     && apt-get install -y --no-install-recommends \
       libsqlite3-dev \

builds/build_python_runtime.sh

@@ -5,6 +5,8 @@ set -euo pipefail
 PYTHON_VERSION="${1:?"Error: The Python version to build must be specified as the first argument."}"
 PYTHON_MAJOR_VERSION="${PYTHON_VERSION%.*}"
 
+ARCH=$(dpkg --print-architecture)
+
 # Python is relocated to different locations by the classic buildpack and CNB (which works since we
 # set `LD_LIBRARY_PATH` and `PYTHONHOME` appropriately at build/run-time), so for packaging purposes
 # we install Python into an arbitrary location that intentionally matches neither location.
@@ -18,6 +20,11 @@ function error() {
 }
 
 case "${STACK}" in
+  heroku-24)
+    SUPPORTED_PYTHON_VERSIONS=(
+      "3.12"
+    )
+    ;;
   heroku-22)
     SUPPORTED_PYTHON_VERSIONS=(
       "3.9"
@@ -63,7 +70,7 @@ case "${PYTHON_MAJOR_VERSION}" in
     ;;
 esac
 
-echo "Building Python ${PYTHON_VERSION} for ${STACK}..."
+echo "Building Python ${PYTHON_VERSION} for ${STACK} (${ARCH})..."
 
 SOURCE_URL="https://www.python.org/ftp/python/${PYTHON_VERSION}/Python-${PYTHON_VERSION}.tgz"
 SIGNATURE_URL="${SOURCE_URL}.asc"
@@ -214,9 +221,8 @@ LD_LIBRARY_PATH="${SRC_DIR}" "${SRC_DIR}/python" -m compileall -f --invalidation
 ln -srvT "${INSTALL_DIR}/bin/python3" "${INSTALL_DIR}/bin/python"
 
 # Results in a compressed archive filename of form: 'python-X.Y.Z-ubuntu-22.04-amd64.tar.zst'
-# TODO: Switch to dynamically calculating the architecture when adding support for Heroku-24.
 UBUNTU_VERSION=$(lsb_release --short --release 2>/dev/null)
-TAR_FILEPATH="${UPLOAD_DIR}/python-${PYTHON_VERSION}-ubuntu-${UBUNTU_VERSION}-amd64.tar"
+TAR_FILEPATH="${UPLOAD_DIR}/python-${PYTHON_VERSION}-ubuntu-${UBUNTU_VERSION}-${ARCH}.tar"
 tar --create --format=pax --sort=name --file "${TAR_FILEPATH}" --directory="${INSTALL_DIR}" .
 zstd -T0 -22 --ultra --long --no-progress --rm "${TAR_FILEPATH}"