Runner Registeration Command for Docker in Docker

gitlab-runner register  --url http://localhost:8000 \
                        --token glrt-qL_FTjkAGqy7SHcYYStx \
                        --executor docker \
                        --name "Docker in Docker Runner" \
                        --docker-image "docker:27.2.0" \
                        --docker-privileged \
                        --docker-volumes "/certs/client" \
                        --docker-network-mode "gitlab-in-docker" \
                        --clone-url "http://gitlab-server:8000"

GitLab Networking

How GitLab runner use /var/run/docker.sock for container creation

How GitLab runner use Docker-in-Docker service for container creation