contrib: add a set of scripts to run pytype in Docker

Having a simple way to run pytype for developers can massively shorten
development cycle. Using the same Docker image and scripts that we use on our
CI guarantees that the result achieved locally will be very similar to (if not
the same as) the output of our CI runners.

Things to note: the Dockerfile needs to do a little dance around user
permissions inside /home/ci-runner/ because:

- on one hand, creating new files on the host (e.g. .pyi files inside .pytype/)
  should use host user's uid and gid

- on the other hand, when we run the image as uid:gid of host user, it needs to
  be able to read/execute files inside the image that are owned by ci-runner

Since local user's uid might be different from ci-runner's uid, we execute this
very broad chmod command inside /home/ci-runner/, but then run the image as the
host user's uid:gid.

There might be a better way to do this.

contrib/docker/pytype/Dockerfile

@@ -0,0 +1,14 b''
+FROM registry.heptapod.net/mercurial/ci-images/mercurial-core:v2.0
+
+USER ci-runner
+
+ENV PATH=/home/ci-runner/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+ENV PYTHONPATH=/home/ci-runner/.local/lib/python3.11/site-packages
+
+RUN python3 -m pip install --user --break-system-packages --upgrade pytype==2023.11.21
+
+ADD --chown=ci-runner entrypoint.sh /home/ci-runner/entrypoint.sh
+
+RUN chmod -R a=rwX /home/ci-runner/.local/ /home/ci-runner/entrypoint.sh
+
+CMD /home/ci-runner/entrypoint.sh

contrib/docker/pytype/entrypoint.sh

@@ -0,0 +1,8 b''
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+cd /tmp/mercurial-ci/
+make local
+./contrib/setup-pytype.sh
+./contrib/check-pytype.sh

contrib/docker/pytype/recipe.sh

@@ -0,0 +1,28 b''
+#!/usr/bin/env bash
+
+# find repo-root without calling hg as this might be run with sudo
+THIS="$(readlink -m "$0")"
+HERE="$(dirname "$THIS")"
+HG_ROOT="$(readlink -m "$HERE"/../../..)"
+echo source mercurial repository: "$HG_ROOT"
+
+# find actual user as this might be run with sudo
+if [ -n "$SUDO_UID" ]; then
+    ACTUAL_UID="$SUDO_UID"
+else
+    ACTUAL_UID="$(id -u)"
+fi
+if [ -n "$SUDO_GID" ]; then
+    ACTUAL_GID="$SUDO_GID"
+else
+    ACTUAL_GID="$(id -g)"
+fi
+echo using user "$ACTUAL_UID:$ACTUAL_GID"
+if groups | egrep -q '\<(docker|root)\>' ; then
+    env DOCKER_BUILDKIT=1 docker build --tag mercurial-pytype-checker "$HERE"
+    docker run --rm -it --user "$ACTUAL_UID:$ACTUAL_GID" -v "$HG_ROOT:/tmp/mercurial-ci" mercurial-pytype-checker
+else
+    echo "user not in the docker group" >&2
+    echo "(consider running this with \`sudo\`)" >&2
+    exit 255
+fi

Makefile

@@ -296,10 +296,12 b' pyoxidizer-macos-tests: pyoxidizer'
 	rm -rf $(PYOX_DIR)/doc
 	cp -a doc $(PYOX_DIR)/doc
 
+pytype-docker:
+	contrib/docker/pytype/recipe.sh
 
 .PHONY: help all local build doc cleanbutpackages clean install install-bin \
 	install-doc install-home install-home-bin install-home-doc \
 	dist dist-notests check tests rust-tests check-code format-c \
 	update-pot pyoxidizer pyoxidizer-windows-tests pyoxidizer-macos-tests \
 	$(packaging_targets) \
-	osx
+	osx pytype-docker