yup! FreeBSD jails are essentially what OP wants with chroot++.

I was pretty puzzled when Docker and LXC came around as this whole new thing believed to have "never been done before"; FreeBSD had supported a very similar concept for years before security groups were added in Linux.

Jails and ezjail were stellar to make mini no-overhead containers when running various services on a server. Being able to archive them and expand them on a new machine was also pretty cool (as long as the BSD version was the same.)