Now there's directory for core libs but there's no git installed by default so it is not possible to use Mineunit lib downloader feature directly, probably also wont be adding git for this image.

Instead of that probably including some preinstalled core libs to keep it lightweight, --fetch-core wont work but libraries can still be included either by mounting default library path or by changing path with --core-root.

Here's also Dockerfile.local I've used to build from Mineunit source directory.

1. Place Dockerfile.local with following contents to local Mineunit source directory.
2. docker build -t mineunit-dev -f Dockerfile.local .
3. docker run -it --rm --mount type=bind,source=$HOME/.minetest/mods,target=/home/mineunit,readonly mineunit-dev

Instead of installing Mineunit from Luarocks it will build directly from source directory therefore including latest / local changes to Docker image.

FROM alpine:latest as build
USER root
ENV USER=root
RUN apk add --no-cache build-base git lua-dev luarocks5.1 lua5.1-sec
RUN luarocks-5.1 install luasocket
RUN luarocks-5.1 install luacov
RUN luarocks-5.1 install busted 2.0.0-1

COPY . /build/mineunit
RUN cd /build/mineunit && luarocks-5.1 make

# Mineunit base
FROM alpine:latest
COPY --from=build /usr/local /usr/local
RUN adduser -D mineunit
RUN mkdir /usr/local/share/lua/5.1/mineunit/core
RUN chown mineunit /usr/local/share/lua/5.1/mineunit/core
RUN apk add --no-cache lua5.1

USER mineunit
WORKDIR /home/mineunit
#ENTRYPOINT ["mineunit"]
ENTRYPOINT ["sh", "-l"]

Tested latest with GitHub actions using slightly modified image (includes git) here: https://github.com/S-S-X/mineunit-test
Seems to work fine and probably as a next step I'm going to integrate this with https://github.com/marketplace/actions/mineunit-runner

This should allow simplest resolution for broken luarocks package manager which currently causes most GitHub Mineunit workflows actions to fail.

DockerHub image is ssxx/mineunit:latest this will probably include git (which makes image a lot larger).
I've planned to release another version without git and maybe including multiple engine core library versions with full docker image.

Pushed latest to https://hub.docker.com/r/mineunit/mineunit with custom built luassert that includes mentioned patch, seems to work without issues. (see: mt-mods/mineunit-actions#12)

For command line exec: docker run --rm -it --mount 'type=bind,source=./,target=/home/mineunit/mod' --entrypoint /bin/sh mineunit/mineunit:latest -lc "cd mod; mineunit"

For bash script:
placed in ~/bin/mineunit to allow calling mineunit like if it was actually installed but run in container and allow access only to current directory.

#!/bin/bash
cmd=("cd" "mod;" "mineunit" "${@}")
docker run --rm -it \
        --mount 'type=bind,source=./,target=/home/mineunit/mod' \
        --entrypoint /bin/sh mineunit/mineunit:latest \
        -lc "${cmd[*]}"