The idea of running virtual machines inside containers is surprisingly old and was used due to several reasons. They include willingness to run VM-s in container orchestration engines like Kubernetes or Borg, or packaging IaaS cloud software like OpenStack in containers. In this presentation, I am going to describe these use cases and two main different approaches of containerizing VM-s - putting every qemu(-kvm) process in a separate container (like Borg or Rancher OS are doing) and putting libvirtd process in container (like OpenStack Kolla or Stackanetes are doing)