Container is an emerging lightweight virtualization technology, and a way to encapsulate software dependencies and simplify deployment. When we started to build Freeshell in 2012, Docker was premature and the dominant container technology was OpenVZ. So we built Freeshell, an elastic and efficient container cloud with OpenVZ. Freeshell attracted 2,000+ users in USTC campus. Our carefully tuned system consolidated 1,000+ active containers into 8 servers.

Freeshell offers multiple pre-created OS images, including Debian, Ubuntu, CentOS, Archlinux and more Linux distributions. To consolidate disk storage of multiple containers, we store the file system of each container as the delta of the base image, and AUFS provides transparency to applications.