Can't speak for anyone else, but while I think jails are "better" for a variety of reasons it seems clear there is far more market momentum behind Docker. More

Can't speak for anyone else, but while I think jails are "better" for a variety of reasons it seems clear there is far more market momentum behind Docker. More particularly, its toolchain. Given the choice between building myself (or relying upon a small, but talented, pool of devs) and drafting off tens of millions in VC cash and a much larger community I think some would prefer the ability to have a *BSD CI chain that is just a config setting in a Docker setup.