Change compression format and S3 URL for Python runtime archives

CHANGELOG.md

@@ -5,6 +5,7 @@
 - Improved the error message shown for EOL Python versions when using a stack for which those versions were never built. ([#1570](https://github.com/heroku/heroku-buildpack-python/pull/1570))
 - Fixed the "Python security update is available" warning being shown when the requested version is newer than the latest version known to the buildpack. ([#1569](https://github.com/heroku/heroku-buildpack-python/pull/1569))
 - Fixed glibc warnings seen when downgrading the stack version. ([#1568](https://github.com/heroku/heroku-buildpack-python/pull/1568))
+- Changed compression format and S3 URL for Python runtime archives. ([#1567](https://github.com/heroku/heroku-buildpack-python/pull/1567))
 - Adjusted compiler options used to build Python for improved parity with the Docker Hub Python images. ([#1566](https://github.com/heroku/heroku-buildpack-python/pull/1566))
 - Excluded `LD_LIBRARY_PATH` and `PYTHONHOME` app config vars when invoking subprocesses during the build. ([#1565](https://github.com/heroku/heroku-buildpack-python/pull/1565))
 

bin/steps/python

@@ -35,7 +35,11 @@ case "${PYTHON_VERSION}" in
     ;;
 esac
 
-PYTHON_URL="${S3_BASE_URL}/${STACK}/runtimes/${PYTHON_VERSION}.tar.gz"
+# The Python runtime archive filename is of form: 'python-X.Y.Z-ubuntu-22.04-amd64.tar.zst'
+# The Ubuntu version is calculated from `STACK` since it's faster than calling `lsb_release`.
+# TODO: Switch to dynamically calculating the architecture when adding support for Heroku-24.
+UBUNTU_VERSION="${STACK/heroku-}.04"
+PYTHON_URL="${S3_BASE_URL}/${PYTHON_VERSION}-ubuntu-${UBUNTU_VERSION}-amd64.tar.zst"
 
 if ! curl --output /dev/null --silent --head --fail --retry 3 --retry-connrefused --connect-timeout 10 "${PYTHON_URL}"; then
   puts-warn
@@ -138,7 +142,7 @@ else
   # Prepare destination directory.
   mkdir -p .heroku/python
 
-  if ! curl --silent --show-error --fail --retry 3 --retry-connrefused --connect-timeout 10 "${PYTHON_URL}" | tar -zxC .heroku/python; then
+  if ! curl --silent --show-error --fail --retry 3 --retry-connrefused --connect-timeout 10 "${PYTHON_URL}" | tar --zstd --extract --directory .heroku/python; then
     # The Python version was confirmed to exist previously, so any failure here is due to
     # a networking issue or archive/buildpack bug rather than the runtime not existing.
     puts-warn "Failed to download/install ${PYTHON_VERSION}"

builds/build_python_runtime.sh

@@ -10,7 +10,7 @@ PYTHON_MAJOR_VERSION="${PYTHON_VERSION%.*}"
 # we install Python into an arbitrary location that intentionally matches neither location.
 INSTALL_DIR="/tmp/python"
 SRC_DIR="/tmp/src"
-UPLOAD_DIR="/tmp/upload/${STACK}/runtimes"
+UPLOAD_DIR="/tmp/upload"
 
 function error() {
   echo "Error: ${1}" >&2
@@ -213,12 +213,12 @@ LD_LIBRARY_PATH="${SRC_DIR}" "${SRC_DIR}/python" -m compileall -f --invalidation
 # This symlink must be relative, to ensure that the Python install remains relocatable.
 ln -srvT "${INSTALL_DIR}/bin/python3" "${INSTALL_DIR}/bin/python"
 
-# The tar file is gzipped separately, so we can set a higher gzip compression level than
-# the default. In the future we'll also want to create a second archive that used zstd.
-# Results in a compressed archive filename of form: 'python-X.Y.Z.tar.gz'
-TAR_FILEPATH="${UPLOAD_DIR}/python-${PYTHON_VERSION}.tar"
+# 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 --create --format=pax --sort=name --file "${TAR_FILEPATH}" --directory="${INSTALL_DIR}" .
-gzip --best "${TAR_FILEPATH}"
+zstd -T0 -22 --ultra --long --no-progress --rm "${TAR_FILEPATH}"
 
 du --max-depth 1 --human-readable "${INSTALL_DIR}"
 du --all --human-readable "${UPLOAD_DIR}"