[openstack-dev] Is there a way to let nova schedule plugin fetch glance image metadata

zhiwei zhiweik at gmail.com
Thu Aug 14 02:22:30 UTC 2014


Thanks Jay.

The scheduler plugin is not a scheduler filter.

We implemented a scheduler instead of using nova native scheduler.

One of our scheduler component need to fetch image metadata by image_id( at
this time, there is not instance ).


On Thu, Aug 14, 2014 at 9:29 AM, Jay Pipes <jaypipes at gmail.com> wrote:

> On 08/13/2014 08:31 PM, zhiwei wrote:
>
>> Hi all,
>>
>> We wrote a nova schedule plugin that need to fetch image metadata by
>> image_id, but encountered one thing, we did not have the glance context.
>>
>> Our solution is to configure OpenStack admin user and password to
>> nova.conf, as you know this is not good.
>>
>> So, I want to ask if there are any other ways to do this?
>>
>
> You should not have to do a separate fetch of image metadata in a
> scheduler filter (which is what I believe you meant by "plugin" above?).
>
> The filter object's host_passes() method has a filter_properties parameter
> that contains the request_spec, that in turn contains the image, which in
> turn contains the image "metadata". You can access it like so:
>
>  def host_passes(self, host_state, filter_properties):
>      request_spec = filter_properties['request_spec']
>      image_info = request_spec['image']
>      # Certain image attributes are accessed via top-level keys, like
>      # size, disk_format, container_format and checksum
>      image_size = image_info['size']
>      # Other attributes can be accessed in the "properties" collection
>      # of key/value pairs
>      image_props =  image.get('properties', {})
>      for key, value in image_props.items():
>          # do something...
>
> Best,
> -jay
>
>
>
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