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

[Oren Laadan]

Serge E. Hallyn wrote:
> Quoting Oren Laadan (orenl at 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.
> 

How about linux plumbers ?

Oren.

> 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.
> 
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