Open Stack

On Dec 21, 2012, at 10:44 AM, Nikola Đipanov <ndipanov at redhat.com> wrote:

> On 21/12/12 18:51, Vishvananda Ishaya wrote:
>> 
>> On Dec 20, 2012, at 9:18 PM, Jian Hua Geng <gengjh at cn.ibm.com
>> <mailto:gengjh at cn.ibm.com>> wrote:
>> 
>>> According to the comments in https://review.openstack.org/#/c/18469/,
>>> I summary the following work items need to be done, pls give me your
>>> suggestion:
>>> 
>>> 1. I prefer to provide a new attribute when run new instance, for
>>> example: --cdrom <image id>
>>> 
>> 
>> This is fine for user experience, but it should still use the block
>> device mapping under the covers.
> 
> An idea I had in mind was to first make use of the 'type' attribute that
> is available in the nova client but is currently not used at all.
> 
> Currently nova help boot gives us:
> 
> --block-device-mapping <dev-name=mapping>
>     Block device mapping in the format
>     <dev-name>=<id>:<type>:<size(GB)>:<delete on-terminate>.
> 
> But a closer look tells me that the type bit is never passed

Type is used to differentiate volumes from snapshots:

https://github.com/4P/python-novaclient/blob/nebula-release/latest/novaclient/v1_1/base.py#L134

But that doesn't stop us from adding image as a possible type as you say below.

> 
> So this could be the first step: generalize your patch to attach images
> as devices if type of the bdm is 'image'. If it is empty it can default
> to 'volume' for example.
> 
> Then we make sure it is safe to use (limit the size etc... what Vish
> mentioned already)
> 
> From there we can continue adding an API extension and some code to
> allow --cdrom (maybe) and code to make sure it attaches properly and
> making it more user friendly.

I don't even know if we need a new api extension. We could just make novaclient construct
a bdm for you if you pass in --cdrom or --volume.
> 
> This is the path I would take - and the reason is that we want to make
> block_device_mappings a facility to keep all the stuff related to
> devices around rather than have it scattered around the nova code-base.

Overall I agree.

Vish