Docker

Docker is an open-source engine which automates the deployment of applications as highly portable, self-sufficient containers which are independent of hardware, language, framework, packaging system and hosting provider.

See also:

Building docker from scratch

Articles

It is essentially Docker, but you can boot bare-metal with it. It even uses Docker under the hood. Every boot is a fresh boot. You can read-write during boot, but all changes are made to ram. You mount with fstab things you want persisted, like home. It uses very simply primitives, which makes it easy to use. Squashfs/grub-mkconfig/overlayfs/etc. Docker isn’t exactly a “primitive”, but it is easily reasoned with. reply – creator comment

Dockerizing applications