gistfile1.txt

198 def get_image_metadata(context, image_api, image_id_or_uri, instance):
199     image_system_meta = {}
200     
201     # Get the system metadata from the instance
202     system_meta = utils.instance_sys_meta(instance)
203     
204     # In case of boot from volume, image_id_or_uri may be None
205     if image_id_or_uri is not None:
206         # It is only safe to use cached image metadata when the requested image
207         # is the same as the instance's image.
208         if image_id_or_uri == instance.image_ref:
209             cached_image = utils.get_image_from_system_metadata(system_meta)
210             
211             # If the instance has inheritable properties, but no other
212             # image metadata cached in system metadata, we will get a
213             # dictionary with only the inheritable properties. In that case,
214             # the image still needs to be pulled from glance.
215             if cached_image and \
216                 ('properties' not in cached_image or len(cached_image) > 1):
217                 return cached_image
218                 
219         # If the base image is still available, get its metadata
220         try:
221             image = image_api.get(context, image_id_or_uri)
222         except (exception.ImageNotAuthorized,
223                 exception.ImageNotFound,
224                 exception.Invalid) as e:
225             LOG.warning(_LW("Can't access image %(image_id)s: %(error)s"),
226                         {"image_id": image_id_or_uri, "error": e},
227                         instance=instance)
228         else:           
229             flavor = flavors.extract_flavor(instance)
230             image_system_meta = utils.get_system_metadata_from_image(image,
231                                                                      flavor)
232                                                                      
233     # Merge the metadata from the instance with the image's, if any
234     system_meta.update(image_system_meta)
235     
236     # Convert the system metadata to image metadata
237     return utils.get_image_from_system_metadata(system_meta)