Bash shell wrapper for running git-runner locally within WSL on a Windows 10 machine using Docker Desktop.

rungit.sh

#!/usr/bin/env bash

if [[ $# -eq 0 ]]
then
        echo "Usage: {up|down|runStages}"
        exit 0
fi

PWD_RESOLVED="$(pwd -P)"

function gitlabLoop() {
        stages=($(echo "$1" | tr ',' '\n'))
        if [ -z "$stages" ]; then
                echo "Running test stage only"
                gitlabExec "test"
        else
                echo "Running stage(s): ${stages[*]}"
                for stage in ${stages[*]};
                        do
                                gitlabExec $stage
                        done
        fi
}

function gitlabExec() {
        docker exec -w $PWD_RESOLVED -it gitlab-runner \
          gitlab-runner exec docker $1 \
          --docker-privileged \
          --docker-disable-cache \                                                                                                                           --cache-dir=/tmp/gitlabrunner \
          --docker-volumes '/var/run/docker.sock:/var/run/docker.sock' \
          --env ROOT_PWD=$PWD_RESOLVED
}

case "$1" in

        ## TO CREATE/START DOCKER CONTAINER FOR GITLAB
        up)
                docker run -d --name gitlab-runner --restart always \
                  -v $PWD_RESOLVED:$PWD_RESOLVED \
                  -v /var/run/docker.sock:/var/run/docker.sock \
                  --workdir $PWD_RESOLVED \
                  -v /srv/gitlab-runner/config:/etc/gitlab-runner \
                  gitlab/gitlab-runner:latest
        ;;

        ## TO RUN RUNNER AFTER GITLAB CONTAINER HAS STARTED
        runStages)
                mkdir -p /tmp/gitlabrunner
                gitlabLoop ${2}
                rm -r /tmp/gitlabrunner
        ;;

        ## TO STOP GITLAB CONTAINER
        down)
                docker stop gitlab-runner
                docker rm gitlab-runner
        ;;
esac

It looks like now you need to write job name and not step name, here is my updated version that worked in WSL2:

#!/usr/bin/env bash

# 1. Start containter: `rungit.sh up`
# 2. Run stage:  `rungit.sh job <job>`
# 3. Stop containter: `rungit.sh down`

if [[ $# -eq 0 ]]
then
        echo "Usage: {up|down|job}"
        exit 0
fi

PWD_RESOLVED="$(pwd -P)"

function gitlabLoop() {
        stages=($(echo "$1" | tr ',' '\n'))
        if [ -z "$stages" ]; then
                echo "Please pass job name"
        else
                echo "Running jobs(s): ${stages[*]}"
                for stage in ${stages[*]};
                        do
                                gitlabExec $stage
                        done
        fi
}

function gitlabExec() {
    echo PWD=$PWD_RESOLVED
    echo JOB=$1
    docker exec -w $PWD_RESOLVED -it gitlab-runner gitlab-runner exec docker $1 --docker-privileged --docker-disable-cache --docker-volumes '/var/run/docker.sock:/var/run/docker.sock' --env ROOT_PWD=$PWD_RESOLVED
}

case "$1" in

        ## TO CREATE/START DOCKER CONTAINER FOR GITLAB
        up)
                docker run -d --name gitlab-runner --restart always \
                  -v $PWD_RESOLVED:$PWD_RESOLVED \
                  -v /var/run/docker.sock:/var/run/docker.sock \
                  --workdir $PWD_RESOLVED \
                  -v /srv/gitlab-runner/config:/etc/gitlab-runner \
                  gitlab/gitlab-runner:latest
        ;;

        ## TO RUN RUNNER AFTER GITLAB CONTAINER HAS STARTED
        job)
                mkdir -p /tmp/gitlabrunner
                gitlabLoop ${2}
                rm -r /tmp/gitlabrunner
        ;;

        ## TO STOP GITLAB CONTAINER
        down)
                docker stop gitlab-runner
                docker rm gitlab-runner
        ;;
esac

I've updated this for a bit more robustness and to make it almost functionally equivalent to running Docker in Docker on Gitlab CI. I haven't tested under WSL, but it works great on macOS and should still work in Linux.

https://gist.github.com/dragon788/485a483f20bcb205bd75866cbfb921f6

You might find https://gitlab.com/cunity/gitlab-emulator useful

Aha! I just realised that exec doesn't work for jobs that are included from other files.