[Libguestfs] Appliance image. Why raw?

Pavel Butsykin pbutsykin at virtuozzo.com
Tue Jun 20 15:48:16 UTC 2017


On 20.06.2017 18:41, Richard W.M. Jones wrote:
> On Tue, Jun 20, 2017 at 06:34:28PM +0300, Pavel Butsykin wrote:
>> On 20.06.2017 17:47, Richard W.M. Jones wrote:
>>> On Tue, Jun 20, 2017 at 05:04:53PM +0300, Pavel Butsykin wrote:
>>>> I noticed that raw is intentionally used as image format for appliance
>>>> image. So I would like to ask, is there any reason to use raw as image
>>>> format for appliance?
>>>
>>> The simple answer is because we create the appliance image (it's an
>>> ext2/3/4 filesystem) using e2fsprogs, and that library wouldn't know
>>> how to create anything else since it always assumes it's writing
>>> directly to a device.
>>>
>>> https://github.com/libguestfs/supermin/blob/master/src/format_ext2.mli#L22-L29
>>>
>>> HTH,
>>
>> Yes, the main point is clear, thanks.
>>
>> I asked because we supply the prepared appliance, so would like to use
>> qcow2. Given that the applaince image is completely controlled, for
>> supermin and fixed appliance, in both the cases. We could use
>> autodetect, it is already implemented in qemu, so to add it to
>> libguestfs will simply. I'm going to prepare the patches, what do you
>> think?
> 
> ./configure-time option? >
> Autodetection is actually not insecure with modern qemu, but people
> still think it is ...

Yes, but in our case it will be safe, because we have full control over
appliance image.
> Rich.
> 




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