It doesn't need to be systemd, and that's the beauty of Rocket's design: it is composed of individual, well defined pieces with precise boundaries and areas of responsibility. As I wrote, my main practical concern now is to get something container-like working on FreeBSD. Docker is useless here unless it's wholly ported; Rocket is useful even if I don't use its code and go with (even partial) implementation of the spec.
From my practical POV, my options now are: port Docker (NOPE), reimplement Docker (NOPE GOD WHY), port Rocket (Maybe?), reuse spec and pieces of Rocket's code in my own opinionated NIH plumbing (Hell yeah, somebody did the thinking part for me! The spec is usable!), or write own opinionated NIH plumbing from scratch (why would I if there's a decent spec to lean on?).
