
Ask HN: What's wrong with FreeBSD Jails? - akandiah
I see a lot of people going with Docker for shipping products. Why don&#x27;t more people choose Jails? Is there anything wrong with it? From what I can gather it&#x27;s a far more mature implementation of containers.
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debdrup
My guess would be that it's because jails are exclusive to FreeBSD, and not
that many people (compared to Linux, that is) run FreeBSD. Jails were also
devised as a tool for the sysadmins toolbox, whereas docker is a tool for
developers toolbox - and each has its own strengths and weaknesses.

Finally, jails do lack a bit of the functionality that lets docker do some
things - but that isn't something that can't exist, an in fact there are
certain signs that such instrumentation might be in the process of being
written:
[https://twitter.com/FiLiS/status/894651614002393088](https://twitter.com/FiLiS/status/894651614002393088).

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brudgers
Docker runs on Linux. Docker runs on Mac. Docker runs on Windows. Not running
on those platforms is an engineering tradeoff Jails makes. There's nothing
wrong with that tradeoff but it does have hard implications.

~~~
debdrup
Docker runs on FreeBSD too, and it'll hopefully run even better in the future
once the results from
[https://wiki.freebsd.org/DockerHackDay2017](https://wiki.freebsd.org/DockerHackDay2017)
come in.

FreeBSD jails can't just be easily ported to any platform, as they're not
designed for portability - kernel-features being portable wasn't really a
thing back in the late 1990s when jails were developed. They're designed to
contain software (in fact, the title of the original paper is quite
demonstrably "confining the omnipotent root"), which is why they're the first
actual type of container (chroots original purpose isn't known by anyone but
Bill Joy and while he isn't saying anything much on the subject, its first
documented use that I know of was building BSD in a clean enviroment).

