# Glance Spec Lite¶

## Return 409 if removing/replacing the location of an image that’s not active¶

problem: When show_multiple_locations is set to True, users currently can remove or replace locations of an image irrespective of the image status. This can result in bad experiences for the users:- 1) If one tries to change or remove the location for an image while it is in saving state, Glance would be trying to write data to a previously saved location while the user updates the custom location. This results in a race condition. 2) For images that are in queued state and no image data has been uploaded yet, there is no need for an image location to be removed and permitting users to remove the image location can result in a bad experience. However users can be allowed to replace the image location to maintain backward compatibility and also because replacing could mean replacing an empty location by a non-empty image location. 3) For images in deactivated state, it is essential that image locations are not updated as it does not abide with the purpose of the image state being set to deactivated and may cause security concerns. 1) Return Conflict Error (409 response code) if an attempt to remove the image location is made when the status of the image is anything but active. 2) Return Conflict Error (409 response code) if an attempt to replace the image location is made when the status of the image is anything but active or queued. A Conflict Error will be thrown preventing users from removing an image location when the image status is not active and replacing an image location when the image status is not active or queued. Expected to be merged within the ocata-1 time frame. https://review.openstack.org/#/c/366995/ Nikhil Komawar, Dharini Chandrasekar

## Expand hypervisor_type metadata with Virtuozzo hypervisor¶

problem: Currently it is not possible to require Virtuozzo hypervisor by specifying hypervisor_type metadata, though Nova has had Virtuozzo support since the Kilo release. We need to expand etc/metadefs/compute-hypervisor.json hypervisor_type property with the appropriate identifier, ‘vz’, as defined in http://git.openstack.org/cgit/openstack/nova/tree/nova/compute/hv_type.py. This will have documentation impact. Release note should be added to notify interested parties about this addition. Expected to be merged within the O-2 time frame. https://review.openstack.org/#/c/341623/ Maxim Netratov

## Add ploop to the list of supported disk formats¶

problem: Currently ‘ploop’ format is not among supported by default disk formats, even though it’s been supported by Nova since the Kilo release. disk_formats configuration option needs to be updated to add ‘ploop’ as one of the supported format. This will have documentation impact. Release note should be added to notify interested parties about this addition. Expected to be merged within the O-2 time frame. https://review.openstack.org/#/c/341633/ Maxim Netratov

## Use Range HTTP header instead of Content-Range for parsing requests¶

problem: When a HTTP request for a partial image download is sent, currently the Content-Range header is parsed to get the byte range from the request. Per RFC 7233 specification, the desired byte range should be specified in HTTP requests using the Range header rather than the Content-Range header. The latter is reserved for responses to such requests. Current implementation requires users to send requests that are not compatible with this specification. For example, a user has to give “bytes 12-30/32” instead of “bytes=12-32”. Parse the Range header from HTTP requests and send a Content-Range entity header with the server response. Deprecate and retain the current support for Content-Range header requests for backward compatibility reasons. Users will be able to send partial download requests using the Range header in the requests with the appropriate value formats. For developers, the Range webob parser does not have a length attribute. We will have to pass the image size explicitly and perform checks to identify an unsatisfiable byte range request from the parsed Range header. This change will also require an API version bump. Expected to be merged within the Ocata time frame. https://review.openstack.org/#/c/367528/ Dharini Chandrasekar