[libvirt] Re: kernel summit topic - 'containers end-game'
Quoting Oren Laadan (orenl(a)cs.columbia.edu):
Serge E. Hallyn wrote:
> A topic on ksummit agenda is 'containers end-game and how do we
> get there'.
>
> So for starters, looking just at application (and system) containers, what do
> the libvirt and liblxc projects want to see in kernel support that is currently
> missing? Are there specific things that should be done soon to make containers
> more useful and usable?
>
> More generally, the topic raises the question... what 'end-games' are
there?
> A few I can think of off-hand include:
>
> 1. resource control
> 2. lightweight virtual servers
> 3. (or 2.5) unprivileged containers/jail-on-steroids
> (lightweight virtual servers in which you might, just
> maybe, almost, be able to give away a root account, at
> least as much as you could do so with a kvm/qemu/xen
> partition)
> 4. checkpoint, restart, and migration
>
> For each end-game, what kernel pieces do we think are missing? For instance,
> people seem agreed that resource control needs io control :) Containers imo
> need a user namespace. I think there are quite a few network namespace
> exploiters who require sysfs directory tagging (or some equivalent) to
> allow us to migrate physical devices into network namespaces. And
> checkpoint/restart needs... checkpoint/restart.
Heh ... it does need ... checkpoint/restart; and a few issues
which we should think about sometime --
Yup, these are all things we need to discuss. For some of them we might
just need to flail about and code a few approaches until we figure out an
answer, but then I think that everyone has thought about a few of these
in some detail, so there probably is much we could gain from talking.
... Does this mean we should try to have a mini-summit in the next 6
months or so? I'd recommend having one right before kernel summit so
we can get our act together, but getting everyone to tokyo to chat seems
uneconomical :) It'd be good to chat about at least the first two items
before the summit, though.
Maybe after we finish v17, we pick a few of these and try a focused push
to get answers?
* Encapsulation of machine/OS config capabilities
- how to detect (versioning, capabilities) ?
- how to deal with mismatches ? (bail ? emulate ? hope for the best ?)
- what happens if, e.g. VDSO page changes, or how to detect FPU changes...
* Conversion of checkpoint image between kernel version (and automation)
* Network namespaces, mnt namespaces - what's the best approach ?
* Security assessment and brainstorming
* Appealing use-cases for everyday use:
- for hybernation
- to reboot to new kernel without losing your session
- to time travel back to before you lost in "bejewled"
* Userspace tools - mainly for inspection of checkpoint images
* Testing frameworks
* Distributed c/r ?
* Optimizations: low downtime, pre-copy, post-copy, cow, parallelization
Now I really go hide :p
Oren.