A brother from another mother: https://bastillebsd.org/ Bastille manages jails using shell with many of the same constructs you'd find in docker. I like it over other jail management software in BSD because it has so few dependencies.
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Currently I'm going through a phase of building and managing jails with just the stuff in FreeBSD base, but that's entirely intended to only be a phase - it'll last until I have the way all of it fits together burned into my brain well enough to be confident debugging it, and then I'll stop banging rocks together and go back to using higher level tools like a sensible person :D