From CoreOS comes "rkt": DESCRIPTION="A fast, composable, and secure App Container runtime for Linux" HOMEPAGE="https://coreos.com/rkt/docs/" Code is available from: https://github.com/coreos/rkt Would be great to have an ebuild for that in Gentoo.
I'm working with user steveeJ in my overlay to get a proxy-maintained version of this into the tree. It's not yet in my overlay and once in should quickly be ready to move to the tree. Keep an eye on https://github.com/alunduil/alunduil-overlay/pull/21 for updates.
app-emulation/rkt-0.8.0 is in the tree.