[libvirt] Re: kernel summit topic - 'containers end-game'

["Serge E. Hallyn" <serue@us.ibm.com>]

Quoting Oren Laadan (orenl@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.