docker: images to build kernels, run static tests and selftests

[matttbe]

The idea here is to have some docker images that are closed to the current CI environment, to easily run the same tests as the ones executed on NIPA. So instead of installing a bunch of dependences, and trying to guess which versions are used on NIPA, these containers can be used. The CI is not currently using these images, but that might be the case later.

These images are supposed to be easy to use and maintain. They are going to be built and pushed to the GitHub registry each time the related files are modified. The Dockerfile are also kept simple to let more people modifying them if needed: at the end it is just a bunch of commands someone would execute to install programs on their side.

To use them, that's easy: for the selftests, simply follow the instructions from the wiki and prefix each vng and make command by something like this:

cd $linux
docker run \
    -v "${CCACHE_DIR}:/home/nipa/.ccache:rw" \
    -v "${PWD}:${PWD}:rw" \
    -w "${PWD}" \
    -u "${RUID:-$(id -u)}:${RGID:-$(id -g)}" \
    --group-add "$(grep "^kvm:" /etc/group | cut -d: -f3)" \
    --rm \
    -i -t \
    --privileged \
    --pull always \
    ghcr.io/linux-netdev/nipa-selftests:latest \
    <vng|make> (...)

(--privileged is needed to access /dev/kvm, -t shouldn't be used if there is no tty)

For the static/build tests:

cd $linux
b4 send -o /tmp/b4

cd $nipa
docker run \
    -v "${CCACHE_DIR}:/home/nipa/.ccache:rw" \
    -v "${PWD}:${PWD}:rw" \
    -v "${linux}:${linux}:rw" \
    -v "/tmp/b4:/tmp/b4:ro" \
    -w "${PWD}" \
    -u "${RUID:-$(id -u)}:${RGID:-$(id -g)}" \
    --rm \
    -i -t \
    --pull always \
    ghcr.io/linux-netdev/nipa-build:latest \
    ./ingest_mdir.py \
          --mdir /tmp/b4 --tree $linux --result-dir out

An alias (or script) can be used to avoid typing such long commands.

Once merge, the wiki page will be updated.