[Lxc-users] Broken my lxc vms

[Nigel Magnay]

I think this is just pure operator error.

I noticed my config file was 0ed at some point, and I think this is
because I missed a '-f' when specifying lxc-create. It now seems to be
much happier (!)

Thanks for the pointers though.

On Sat, Apr 3, 2010 at 5:10 PM, Gordon Henderson <gordon at drogon.net> wrote:
> On Sat, 3 Apr 2010, Nigel Magnay wrote:
>
>>>> I'm seeing things like
>>>>
>>>> root <at> nirima-host:/home/magnayn# lxc-start -n ubuntu
>>>> swapon: /dev/disk/by-uuid/35b40dbb-337c-4f46-a82f-642d6fbf3faa: swapon
>>>> failed: Device or resource busy
>>>>
>>> OK - I'm relatively new to LXC (couple of months), I also use Debian not
>>> Ubuntu, but to me, it looks like your container is executing a whole bunch
>>> of init-scripts that it shouldn't be executing. (or really doesn't need
>>> to)
>>>
>>> In my containers, I just have /etc/init.d/rcS with nothing more than a
>>> line to create a default route (as the network is already created with
>>> lxc-start). The line
>>>
>>>   exec /etc/init.d/rc S
>>>
>>> is commented out. That's the ones in Debian that'll normally do stuff with
>>> hardware like activate swap, fsck, etc.
>>>
>>
>> Hm - I've tried rebooting the machine, which didn't help. Note that
>> this image *used* to work; something has
>> gotten corrupted somewhere, possibly when it was non-gracefully shutdown.
>>
>> I'm a bit confused;
>> /dev/disk/by-uuid/35b40dbb-337c-4f46-a82f-642d6fbf3faa is swap in the
>> outer machine, not the
>> image itself. Why is lxc-start trying to turn on the swapfile (when
>> it's already on) ?
>>
>> Either way, it's probably a red-herring; I can get past that but it
>> still freezes..
>
> I'm not sure it should see that though - make sure your init scripts are
> not trying to swapon, or fsck, etc. and make sure it's not in your
> /etc/fstab.
>
> Same for other things - really, in a container all I'm running is syslogd,
> sshd, apache and then either mysql or asterisk depending on it's use...
>
> No NTP, hwmonitoring, mdadm, snmp, etc. as that's all being done on the
> host. (actually there may be a case for snmp if you're remotely checking
> the network stats)
>
>>>> Also - lxc looks exactly what I want to isolate some app servers into
>>>> individual units. Is lxc considered reasonably stable (as it's
>>>> mainline now), or should I steer clear for a bit ?
>>>
>>> I've jumped in at the deep end - did a lot of local testing myself
>>> including running 50 containers on an old server, starting/stopping,
>>> running applications, etc. each running a standard LAMPy type thing - and
>>> Asterisk... And was happy enough with it to start to migrate a lot of
>>> remote hosted servers over to it, and have decided to build all my server
>>> from now on with containers in-mind.
>>
>> Good to know; I'm just slightly nervous as these initial tests have
>> broken an image that was working, so I'd like to know
>> why before I get a problem if I run it live..
>
> I had a lot of "breakages" when starting out too - but once I culled all
> the init scripts everything went much smoother. Also watch out for the
> shutdown scripts too - so that if you shotdown a container (from inside
> the container with shutdown/reboot/init 0) then it doesn't try to unmount,
> or shutdown mdadm devices, etc. which may affect the host.
>
> I'm not sure an LXC container is secure enough at present to allow root
> access to someone you don't trust, but I guess with proper use of limiting
> the underlying hardware the container can access it might be...
>
> I'm using it as a management tool to better maintain a small raft of
> servers that I operate.
>
> Gordon
>
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