[libvirt] simple LXC/libvirt busybox container (Unable to get cgroup)

[Ryota Ozaki]

On Thu, Dec 10, 2009 at 5:22 PM, Tony Risinger
<sweetsinsemilla at gmail.com> wrote:
> i'm trying to get even the simplest busybox container with libvirt+LXC
> with very limited success.  I feel l am missing something supremely
> simple for me to be hung on this for weeks.
>
> i dont see anything interesting in domain log, but getting this error
> from "LIBVIRT_DEBUG=1 libvirtd":
>
> 05:27:56.113: error : lxcDomainGetInfo:462 : internal error Unable to
> get cgroup for arch-nano
> 05:27:56.113: debug : virDomainFree:2004 : domain=0x81d8e68
> 05:27:56.113: debug : virUnrefDomain:422 : unref domain 0x81d8e68 arch-nano 1
> 05:27:56.113: debug : virReleaseDomain:376 : release domain 0x81d8e68 arch-nano
> 05:27:56.113: debug : virReleaseDomain:392 : unref connection 0x81dc0f0 2
> 05:27:56.113: debug : remoteSerializeError:141 : prog=536903814 ver=1
> proc=16 type=1 serial=4, msg=internal error Unable to get cgroup for
> arch-nano
>
> i've been using this root filesystem layout:
>
> [root at PHS-001 arch-nano]# tree
> .
> |-- bin
> |   |-- cat -> ../sbin/busybox
> |   |-- chdir -> ../sbin/busybox
> |   |-- chmod -> ../sbin/busybox
> |   |-- ls -> ../sbin/busybox
> |   |-- rm -> ../sbin/busybox
> |   |-- sh -> ../sbin/busybox
> |   `-- vi -> ../sbin/busybox
> |-- dev
> |   `-- pts
> |-- etc
> |-- proc
> |-- sbin
> |   |-- busybox
> |   `-- init -> busybox
> `-- sys
>
> all folders besides /bin and /sbin were created by libvirt.  i tried
> using the /sbin/init script previously suggested:
>
> #!/sbin/busybox
> sh
>
> but i get a similar results either way (script/symlink):
>
>  8173 ?        Ss     0:00 /usr/lib/libvirt-git/libvirt_lxc --name
> arch-nano --console 11 --background
>  8175 pts/0    Ss+    0:00 init
>  8177 ?        Ss     0:00 init
>  8181 ?        Zs     0:00 [init] <defunct>
>  8182 ?        Zs     0:00 [init] <defunct>
>  8183 ?        Zs     0:00 [init] <defunct>
>
>
> "busybox init" doc says that without an /etc/inittab, sh will be
> started on /dev/tty2... im am using this config:
>
> <domain type='lxc'>
>  <name>arch-nano</name>
>  <memory>500000</memory>
>  <os>
>    <type>exe</type>
>    <init>/sbin/init</init>
>  </os>
>  <devices>
>    <filesystem type='mount'>
>      <source dir='/vps/dom/arch-nano'/>
>      <target dir='/'/>
>    </filesystem>
>  </devices>
> </domain>
>
> on this config i tried removing the console/serial section altogether,
> but i attempted many configurations of serial/console, including
> changing the <target> to "2", in attempt to match busybox default.
>
> [root at PHS-001 arch-nano]# virsh -c lxc:/// console arch-nano
> error: Unable to get domain status
> error: internal error Unable to get cgroup for arch-nano
>
> [root at PHS-001 arch-nano]# mount | grep cgroup
> none on /cgroup type cgroup (rw)
>
> if anyone can please point out what i am doing wrong to not be able to
> move the root and get a console, i'd greatly appreciate it.  ive been
> really stuck on this; i'd rather not write a bunch of scripts/wrappers
> for lxc-* tools when libvirt does it all splendidly already!

I'm successfully using lxc via lbivirt. I doubt ns subsystem of cgroups
because I usually disable it that is the difference between my
configuration and yours and if I enable it I also get the same error.

So could you try without ns? like:
  mount -t cgroup -o memory,devices,cpu,cpuacct none /cgroup

I think libvirt lxc still contains a problem around ns subsystem.

  ozaki-r

>
> libvirt 0.7.4+
> kernel 2.6.32 (am i missing a CONFIG_*?)
>
> thanks for your time
>
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