Allow creating of local docker images before running tests

Feature disposition status (2022-12-22)

We do not plan to implement this feature.

Overview

We really like the idea of running our tests in a container, but the current gitlab-ci docker support is a bit limiting in terms of the base image you can use. If you have a Python app you can use the standard python:2/3 base image, but then on every test you need to re-install all pip dependencies/system packages. Is there a way to use the local dockerfile for the project instead?