[Kimchi-devel] [RFC]Create VM from image

[Royce Lv]

On 2014年07月02日 04:07, Christy Perez wrote:
>
>
> On Tue, 2014-07-01 at 15:53 +0800, Royce Lv wrote:
>> Currently kimchi just support create a vm from an ISO defined template.
>> This requires duplicate installation.
>> This release we want to support create a vm from an installed image.
>>
>> This involves the following change:
>>
>> 1. Create a template from an image:
>>
>> POST /templates/template-1
>>       {'base': 'abs_base_img_path'}
>>
>> Implementation:
>>       (1)probe image os distro and version to get suggested config.
>>       (2)Avoid image to be deleted.
>>       (3)Avoid using ISO and base image at the same time.
>>
>> 2. Create a vm from image based template:
>>       This part has already been covered by Aline's prototype patch.
>>
>>       POST /vms/vm-1
>>           {'storagepool': 'default', 'network': 'default',
>> 'disks':[{'index':0, 'base': 'abs_path'}]}
>>       or
>>           {'storagepool': 'default', 'network': 'default',
>> 'disks':[{'index':0, 'base': 'abs_path', 'volume': 'scsi_volume'}]}
>>
>>       The create vm implementation need to be re-considered for the
>> following points:
>>       (1) when creating vm on scsi/iscsi pool, if volume size smaller
>> than original image, need to be rejected.
>>       (2) when creating vm on directory based pool, volume generating
>> logic is different with allocation new volume.
>>       (2) xml generating need to be refactored.
>>
>> Anything else need to be considered, welcome your comments.
>>
> this might be something for down the line, but some distros (not sure
> which, other than Ubuntu) or even private organizations, keep image
> files online too. So we might want to think about allowing remote images
> to be used. This would have to be different than the remote template
> logic, of course, since we would want to pull the image down into a
> storage pool and then use it locally.
>
> Scroll to the bottom: http://cloud-images.ubuntu.com/precise/current/
> http://cloud-images.ubuntu.com/
Thanks Christy!

That is exactly what I want for this feature.Together with what I posted 
in RFC "Upload and download image for OOTB storage pool".
The whole flow of this scenario will be:
1. download a cloud image to ISO storage pool.
2. create a template from this cloud image.
3. create a vm from this template.

I agree with you that this is different from the remote template logic, 
because this image is the base image of other vms. And other vms' image 
file is cow image of this base.
If this base image locates remotely, I'm afraid this will be an IO 
bottleneck of the VM. This is different with ISO streaming, because ISO 
is only used one time when installation, but this base image file will 
be used every time read occurs.
>
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>>
> Regards,
>
> - Christy
>
>
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