[lxc-devel] nested containers

[S.Çağlar Onur]

Hi,

On Sat, Dec 28, 2013 at 5:21 AM, Stéphane Graber <stgraber at ubuntu.com> wrote:
> On Fri, Dec 27, 2013 at 06:56:15PM -0500, S.Çağlar Onur wrote:
>> Hey Pauk,
>>
>> On Fri, Dec 27, 2013 at 6:49 PM, Paul Wexler
>> <paul at prometheusresearch.com> wrote:
>> > Hello lxc community,
>> >
>> > Has anyone used nested containers?
>> >
>> > I am trying with limited success.  I cannot re-start them.
>> > I can:
>> >   1. create a container.
>> >   2. configure it for nesting (I uncomment 2 lines in config).
>> >   3. start the container.
>> >   4. stop the container.
>> >   5. but I cannot re-start the container.
>> >
>> > However, if I do not configure the container for nesting then
>> > I can stop and re-start the container repeatedly without errors.
>> >
>> > Specifically, the following command line sequence fails on the
>> > second lxc-start (please note I do not show the normal lxc-
>> > output below, only the error msg):
>> >
>> >   # lxc-create -t ubuntu -n C00
>> >   # X="lxc.aa_profile = lxc-container-default-with-nesting"
>> >   # sed -i -e "s/^#$X/$X/" /var/lib/lxc/C00/config
>> >   # X="lxc.hook.mount = /usr/share/lxc/hooks/mountcgroups"
>> >   # sed -i -e "s/^#$X/$X/" /var/lib/lxc/C00/config
>> >   # lxc-start -d -n C00
>> >   # lxc-stop -n C00
>> >   # lxc-start -d -n C00
>> >   lxc-start: command get_cgroup failed to receive response
>>
>> I believe this issue fixed after alpha has been released [1] so could
>> you try replacing your mountcgroups hook with [2] and try again to see
>> what will happen?
>
> Right, the issue here appears to be mountcgroups not cleaning up after
> itself and being confused on the second run.

Oh, right I misunderstood the problem and though starts are failing
due to lxc.include.

> Hopefully we'll be dropping that hook entirely with the introduction of
> cgmanger in the next few weeks...
>
> Depending on what you are doing, you may also just comment that hook
> entirely as cgroup-lite in the container will then simply mount the
> cgroupfs controllers and LXC will be able to use them (however this will
> most likely bypass any cgroup restriction you applied on the first
> container, if any).

What about removing those leftover cgroup directories in post-stop hook?

>>
>> > When I start the container the first time, lxc-ls --fancy
>> > displays the container's IP address.  Then I can ssh to the
>> > container as 'ubuntu', install packages there such as lxc,
>> > and even create containers there, the container is working
>> > just fine.
>> >
>> > But once I stop the container I can never start it again.
>> > Always with the same get_cgroup error as above.
>> >
>> > I am using:
>> >   lxc version ==  '1.0.0.alpha2'
>> >   kernel == 3.11.0-12-generic
>> >
>> > Any ideas/suggestions on how one might re-start such a container?
>> > Thank you.
>> >
>> >
>> > _______________________________________________
>> > lxc-devel mailing list
>> > lxc-devel at lists.linuxcontainers.org
>> > http://lists.linuxcontainers.org/listinfo/lxc-devel
>> >
>>
>> [1] https://github.com/lxc/lxc/commit/fa7fced87899ae37f193c81115543d1df5c28fbb
>> [2] https://raw.github.com/lxc/lxc/master/hooks/mountcgroups
>>
>> Best,
>> --
>> S.Çağlar Onur <caglar at 10ur.org>
>> _______________________________________________
>> lxc-devel mailing list
>> lxc-devel at lists.linuxcontainers.org
>> http://lists.linuxcontainers.org/listinfo/lxc-devel
>
> --
> Stéphane Graber
> Ubuntu developer
> http://www.ubuntu.com
>
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>



-- 
S.Çağlar Onur <caglar at 10ur.org>