Detect of BHyve VM was powered off or rebooted?

[Neel Natu]

Hi Craig,

> On Feb 11, 2014, at 2:29 PM, Craig Rodrigues <rodrigc at FreeBSD.org> wrote:
> 
>> On Tue, Feb 11, 2014 at 11:11 AM, John Baldwin <jhb at freebsd.org> wrote:
>> 
>>> On Sunday, February 09, 2014 7:03:41 pm Neel Natu wrote:
>>> Hi Craig,
>>> 
>>> On Sun, Feb 9, 2014 at 1:11 PM, Craig Rodrigues <rodrigc at freebsd.org>
>> wrote:
>>>> Hi,
>>>> 
>>>> I posted some rc.d scripts that I am using to boot a BHyve VM
>>>> and send the output to a serial console using the /dev/nmdm
>>>> driver:
>>>> 
>>>> http://lists.freebsd.org/pipermail/freebsd-virtualization/2014-
>> January/002040.html
>>>> 
>>>> It works quite well.  There is some things I would like to improve,
>>>> and would like some advice on the best way to do it.
>>>> 
>>>> (1)  If the VM was destroyed with bhyvectl --destroy --vm ${VM_NAME},
>>>>      then I do not want to automatically restart the VM in the script.
>>>>      User should manually:  service bhyvevm start
>>>> 
>>>> (2)  If the VM was powered down, via shutdown -p, or halt -p,
>>>>       then in my script I do not want to restart the VM in the script.
>>>>       User should manually:  service bhyvevm start
>>>> 
>>>> (3)   If the VM was rebooted via "reboot" or "shutdown -r",
>>>>       then I *do* want the script to restart the VM.
>>>> 
>>>> I think if I change my start_vm.sh script to do something like:
>>>> 
>>>> 
>>>> 
>>>> (
>>>> while [ -e /dev/vmm/${VM} ]; do
>>>>    /usr/sbin/bhyve -c 16 -m 8G -A -H -P -g 0 -s 0:0,hostbridge -s
>> 1:0,lpc
>>>> -s 2:0,virtio-net,${TAP} -s 3:0,virtio-blk,${IMG} -l com1,${CONS_A}
>> ${VM}"
>>>> done
>>>> 
>>>> )  &
>>>> 
>>>> 
>>>> then this might cover cases (1) and (3), but what will cover
>>>> case (2)?
>>> 
>>> The exit code of the bhyve process will be 0 if it exited because the
>>> guest rebooted and will be non-zero if the guest did an acpi poweroff.
>>> You can use that to distinguish between cases (2) and (3).
>>> 
>>> Having said that there are error conditions for which bhyve exits with
>>> a non-zero exit code. So, we'll need to explicitly define an exit code
>>> to distinguish between an acpi poweroff and these error conditions.
>> 
>> OTOH, in all the cases when bhyve exits with a non-zero exit code, you
>> will want to exit the loop which would treat it the same as shutdown -p.  I
>> think you can just do this:
>> 
>>        while [ -e /dev/vmm/${VM} ]; do
>>                if ! bhyve ...; then
>>                        break
>>                fi
>>        done
> 
> 
> 
> One question, if "bhyve" exits, do I have to call bhyveload again before
> calling bhyve?

Yes, that is correct. You will also need to destroy the VM after bhyve exits.

Best
Neel

> 
> The /usr/share/examples/bhyve/vmrun.sh has a loop which does:
> 
>        while [ 1 ] ; do
> 
>                  ...
>                  bhyvectl --destroy
>                  bhyveload
>                  bhyve
> 
>                   ...
>        done
> 
> --
> Craig
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