libvirt: only CI or CD too?

Hi Steffen, thanks for your work!

If I understand correctly, your libvirt WIP (gitlab-org/gitlab-runner!464 (closed)) implements only the CI functionality. Are you planning to add libvirt runner for CD too, i.e. for Review Apps and deployments in different environments?

Also, if I understood correctly, you are using snapshots and a single instance for running the CI jobs. Why not to create new domains on the fly for each CI/CD job using the image you create with virt-builder as the backing store and an xml definition of the domain as a template, then undefine the domain, removing all its temp storage, when it's no longer needed?