https://gitlab.com/daurnimator/docker-hererocks/blob/master/Dockerfile https://github.com/javierfernandes/lua-circleci/blob/master/.circleci/config.yml https://support.circleci.com/hc/en-us/articles/360000217868-How-do-I-create-a-custom-docker-image-for-CircleCI-
