synapse/.ci/scripts/prepare_old_deps.sh

#!/usr/bin/env bash
# this script is run by GitHub Actions in a plain `focal` container; it
# - installs the minimal system requirements, and poetry;
# - patches the project definition file to refer to old versions only;
# - creates a venv with these old versions using poetry; and finally
# - invokes `trial` to run the tests with old deps.

set -ex

# Prevent virtualenv from auto-updating pip to an incompatible version
export VIRTUALENV_NO_DOWNLOAD=1

# TODO: in the future, we could use an implementation of
#   https://github.com/python-poetry/poetry/issues/3527
#   https://github.com/pypa/pip/issues/8085
# to select the lowest possible versions, rather than resorting to this sed script.

# Patch the project definitions in-place:
# - Replace all lower and tilde bounds with exact bounds
# - Replace all caret bounds---but not the one that defines the supported Python version!
# - Delete all lines referring to psycopg2 --- so no testing of postgres support.
# - Use pyopenssl 17.0, which is the oldest version that works with
#   a `cryptography` compiled against OpenSSL 1.1.
# - Omit systemd: we're not logging to journal here.

sed -i \
   -e "s/[~>]=/==/g" \
   -e '/^python = "^/!s/\^/==/g' \
   -e "/psycopg2/d" \
   -e 's/pyOpenSSL = "==16.0.0"/pyOpenSSL = "==17.0.0"/' \
   -e '/systemd/d' \
   pyproject.toml

# Use poetry to do the installation. This ensures that the versions are all mutually
# compatible (as far the package metadata declares, anyway); pip's package resolver
# is more lax.
#
# Rather than `poetry install --no-dev`, we drop all dev dependencies from the
# toml file. This means we don't have to ensure compatibility between old deps and
# dev tools.

pip install toml wheel

REMOVE_DEV_DEPENDENCIES="
import toml
with open('pyproject.toml', 'r') as f:
    data = toml.loads(f.read())

del data['tool']['poetry']['dev-dependencies']

with open('pyproject.toml', 'w') as f:
    toml.dump(data, f)
"
python3 -c "$REMOVE_DEV_DEPENDENCIES"

pip install poetry==1.2.0
poetry lock

echo "::group::Patched pyproject.toml"
cat pyproject.toml
echo "::endgroup::"
echo "::group::Lockfile after patch"
cat poetry.lock
echo "::endgroup::"