From https://hub.docker.com/r/gitlab/gitlab-runner/dockerfile:
VOLUME ["/etc/gitlab-runner", "/home/gitlab-runner"]
I have read https://stackoverflow.com/questions/41935435/understanding-volume-instruction-in-dockerfile and https://stackoverflow.com/questions/53901320/docker-volume-and-volume-inside-dockerfile, however, I still cannot figure why does this image specify these two paths as VOLUME.