The current Dockerfile assumes the base Debain Python image (python:3.11) which produces a final image that is approximately 1.0 GB in size.

docker build . -t tests:debian
docker image ls | grep "tests:debian"
tests:debian             latest        bbd315631e3e   46 seconds ago   1.09GB

Since GitHub Actions has to build this image at runtime, I propose we use the Slim (python:3.11-slim) image instead. This change produces a final Docker image that is approximately 231 MB in size.

docker build . -t tests:debian-slim
docker image ls | grep "tests:debian-slim"
tests:debian-slim        latest        40f097c44a36   2 seconds ago       231MB

We could get further size reductions if we were to use the python:3.11-alpine image. However, I believe that sticking to a a Debian-based image prevents compatibility issues when using Python libraries with C extensions. I am open to using the alpine Docker image if you are confident that the current dependencies play nice with the Alpine Linux platform. I was able to successfully build and test an Alpine Docker image.

docker build . -t tests:alpine
docker image ls | grep "tests:alpine"
tests:alpine             latest        b6d56e866048   15 minutes ago   139MB
docker run --entrypoint python tests:alpine unit-tests.py
....
----------------------------------------------------------------------
Ran 4 tests in 0.003s

OK