Re: Docker

On 4/12/23 08:38, Mario Marietto wrote:
> ---> Docker will NEVER run on FreeBSD, because Docker is built on technologies which only exist in the Linux kernel.
> 
> I don't agree with this. In my humble opinion Docker can run on FreeBSD. For sure,not using the same technology that it uses on Linux.

By way of introduction, I have been a BSD user before it ever existed
in any form on x86 machinery, starting with Sun workstations and a variety
of machinery thereafter. My first version of FreeBSD was 1.0 and I have also
done Linux platform engineering approaching 20 years now.  Finally, I
have lead teams to deliver Kubernetes/Docker implementation for a
$1 Billion US commercial interest.

I have stayed out of this mostly because I hate listening to internet
"experts" running Linux on their RPis who think they are 1st class
systems engineers.  Also, I generally try to be nice.  But some of the
commentary here show a lack fundamental clarity about what docker
is, how it is implemented, and why it is used.  So, lets see if we can
shine some light on this:

1. Docker is many things.  It is a virtually private filespace running over
    a common Linux kernel.  In this regard, it's basically a high-
    class version of chroot.  And this COULD be reimplemented
    notionally on FreeBSD.  That's roughly what jails do as I recall.

2. Trying to run docker binaries on a FreeBSD kernel might be
    a good science experiment but it would likely be inefficient
    and unstable without a ton of work because the kernel
    architectures of FreeBSD and Linux are fundamentally different.

    There are potentially ways to do this - say running FreeBSD and
    Linux kernels as Mach servers and then writing a bunch of
    userland glue to make it look like docker is running on FreeBSD.
    But it is a nonsensical idea.  It's doesn't solve a problem
    that needs fixing.

3. But docker is far more than this, as the term is normally used.
    It is an entire ecosystem built in layers on top of core
    containerization. Among these include Kubernetes, Swarm, and
    Anthos/Istio just for starters.  Then there's all the third party
    tooling to deploy an manage microservices written using these
    various systems.

    These aren't toys or some hobby hackery, they are commercial grade
    bet-your-business capabilities that aren't going to run on some
    cross-OS experiment.  They represent likely 100s of thousands of man hours
    of work and 10s of millions in expenditure and that's not going to
    get replicated on a volunteer basis anytime soon.

4. You're not going to see docker on FreeBSD in any meaningful way because
    it's not worth doing and doesn't solve a significant problem begging
    to get fixed.

5. Professionals use all the tools in the toolbox when/as
    they make sense.  FreeBSD and Linux coexist happily in some of the
    biggest data centers in the world.  There are commercial NAS
    products written in FreeBSD, for instance, that are plugged into
    networks running hundreds or even thousands of Linux servers.
    The point is, you don't have to choose one, you can choose both.

6. But if you want to have a go at this, here's a way to get started.

    -  Write a userland abstraction for FreeBSD that looks, feels, and
       runs like native docker.

    -  Build *reliable and self annealing* IPCs between that abstraction
       and an actual Linux machine which is truly running docker.  Make
       sure it isn't noticeably slower than just running straight on
       Linux.

    -  When you have this done, you will have given FreeBSD users the
       docker experience you claim is desperately needed.

    - Now all you have to do is port Kubernetes, Swarm, and Isto/Anthos
      over to get the world to come to FreeBSD.  Good luck ...