[libvirt-users] Problem halting/restaring a lxc container from within

[Daniel P. Berrange]

On Thu, Jul 05, 2012 at 01:34:00AM +0200, david at dit.upm.es wrote:
> 
> Hi,
> 
> I've been making some tests with libvirt and LXC and found some problems
> when halting/restarting a LXC container from within.
> 
> Basically, on a Ubuntu 12.04 system with libvirt installed as package
> (0.9.8), I've created a basic container image with:
> 
>  lxc-create -t ubuntu -n lxc
> 
> And started it using the libvirt XML listed below and the following command:
> 
>  virsh -c lxc:// create lxc.xml
> 
> I can access the container console normally but when I issue a halt or
> reboot command from inside, the container initiates the halt/reboot
> execution but it does not finishes it properly.
> 
> For example:
> 
> $ sudo halt -p
> [sudo] password for ubuntu:
> 
> Broadcast message from ubuntu at my-container
> 	(/dev/pts/0) at 23:19 ...
> 
> The system is going down for power off NOW!
> ubuntu at my-container:~$ acpid: exiting
>  * Asking all remaining processes to terminate...    [ OK ]
>  * All processes ended within 1 seconds....          [ OK ]
>  * Deconfiguring network interfaces...               [ OK ]
>  * Deactivating swap...                              [fail]
>  * Unmounting weak filesystems...                    [ OK ]
> umount: /run/lock: not mounted
> mount: / is busy
>  * Will now halt
> 
> The container seems to finish the shutdown process but libvirt does not
> seem to be signaled about it (virsh shows the container is still
> executing). Something similar happens with reboot.
> 
> However, if a start that container with:
> 
>  lxc-start -n lxc
> 
> and do the same test, it works perfectly:
> 
> # sudo halt -p
> [sudo] password for ubuntu:
> 
> Broadcast message from ubuntu at my-container
> 	(/dev/lxc/console) at 23:17 ...
> 
> The system is going down for power off NOW!
> ubuntu at my-container:~$ acpid: exiting
>  * Asking all remaining processes to terminate...        [ OK ]
>  * All processes ended within 1 seconds....              [ OK ]
>  * Deconfiguring network interfaces...                   [ OK ]
>  * Deactivating swap...                                  [fail]
> umount: /run/lock: not mounted
> mount: cannot mount block device
> /dev/disk/by-uuid/9b50a43d-98c3-45ad-a540-7fcbc629a418 read-only
>  * Will now halt
> #
> 
> Any idea about how to investigate/solve this problem??

I don't know why it doesn't halt - with recent kernels if you issue
the reboot() syscall from within the guest, then init process should
exit which libvirt will treat as halted. There are patches pending
to make reboots work too but that's for a future release


Daniel
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