> Yeah, that (sadly) is a good use case.  But surely a proper package
> management system would let you do this too.
>
> - allow more than one version of a package to be installed
>
> - allow more than one instance of the same package, but with different
>   global configuration.  Perhaps global configuration is evil.
>
> - allow package dependencies to contol which versions of each package
>   talk to each other.  For example, if A talks to B, under some
>   conditions, old A should talk to old B
>
> - make sure that distinct package's configurations don't affect each
>   other.  Example: two different packages that use Apache; they should not
>   configure Apache in ways that conflict.

I think Red Hat's software collections are supposed to do that:

https://www.softwarecollections.org

On 22 April 2015 at 17:24, D. Hugh Redelmeier <hugh@mimosa.com> wrote:
>
> | From: Giles Orr <gilesorr@gmail.com>
>
> | I've been using VirtualBox a lot recently, and I've been pretty
> | impressed with it - running more than one simultaneous machine,
> | setting up an internal network and running ansible between them,
> | nifty.
>
> It is a neat trick.
>
> But what is it useful for?
>
> Clearly it is great to be able to run different OSes if you need to
> run more than one.  For example, to be able to run MS Word when you
> mostly want to run Linux.  Or to test on multiple platforms.
>
> In the Libreswan project, we use virtualization to test networking
> software.  Since some of the code is in the OS, we at least sometimes have
> to run different OSes.
>
> But most of virtualization seems to be for other purposes.
>
> |  Today at work we had an interesting discussion about Digital
> | Ocean: the suggestion was made (and undoubtedly it's obvious to many
> | on this list, but it was eye-opening to me, I'm still getting my head
> | around disposable machines) that if you weren't sure an upgrade to a
> | droplet would work, just clone it, do the upgrade on the clone and see
> | how it goes.  Then you can make your decision and destroy the unwanted
> | version.
>
> Yeah, that (sadly) is a good use case.  But surely a proper package
> management system would let you do this too.
>
> - allow more than one version of a package to be installed
>
> - allow more than one instance of the same package, but with different
>   global configuration.  Perhaps global configuration is evil.
>
> - allow package dependencies to contol which versions of each package
>   talk to each other.  For example, if A talks to B, under some
>   conditions, old A should talk to old B
>
> - make sure that distinct package's configurations don't affect each
>   other.  Example: two different packages that use Apache; they should not
>   configure Apache in ways that conflict.
>
> - job migration between machines, even while running, seems useful.
>   (That's not a package management problem.)
>
> One step more towards virtualization:
>
> Jails are minimal and may be good enough but a lot cheaper than
> supporting true virtual x86 machines.
>
> |  All of which made me think "wouldn't it be cool if I could
> | have a system with an totally stripped Linux with VirtualBox as the
> | "Window Manager" so I could toggle between two or three running OSes
> | with graphical interfaces ..."  So:
>
> I think that Serious VMware products are stripped Linux systems that
> can run VMs without a lot of extras.
>
> I think that Zen Dom0 (host) can be minimal too.
>
> So much of the noise this day is about things like Docker and CoreOS.
> A lot feels like branding exercises rather than technology.  I find it
> too hard to figure out what they actually are.
> ---
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