Standardize Nova Image

Standardize Nova Image

https://blueprints.launchpad.net/nova/+spec/standardize-nova-image

Standardize Nova’s nova.image module to work like nova.network.api and nova.volume.cinder.

Problem description

For some reason, nova.image does things differently than nova.volume and nova.network. Instead of nova.compute.manager instantiating a self.image_api object, like it does for self.network_api and self.volume_api, the compute manager calls an obtuse collection of nova.image.glance module calls.

This blueprint is around the work to make a new nova.image.api module and have it called like other submodule “internal APIs” in Nova.

Proposed change

A new nova.image.api module shall be created, following in the style of nova.network.api and nova.volume.cinder. There will be an API class in the nova.image.api module that follows identical conventions as the nova.volume.cinder.API class, with methods for listing (get_all), showing (get), creating (create), updating (update), and removing (delete) images from the backend image store. There will be a nova.image.driver module with a base driver class.

The nova.image.glance module will be updated to subclass the base driver class.

Alternatives

There is a series of patches in review up for Nova that tries to add support for Glance’s V2 API operations:

https://review.openstack.org/#/q/status:open+project:openstack/nova+branch:master+topic:bp/use-glance-v2-api,n,z

Unfortunately, I believe this patch series further muddies the image service inside Nova instead of making it cleaner and standardized with the rest of Nova’s external API interfaces.

The idea of this blueprint is to lay a good foundation for future V2 Glance API work by first standardizing the image API inside of Nova.

Data model impact

None

REST API impact

None

Security impact

None

Notifications impact

None

Other end user impact

None

Performance Impact

None

Other deployer impact

None

Developer impact

See above link to Eddie Sheffield’s patch series that would be affected by the code in this blueprint. Hopefully, however, once the image API is brought in line with the other internal-to-external Nova APIs, the work on V2 Glance API should be quite a bit easier.

Implementation

Assignee(s)

Primary assignee:

jaypipes

Work Items

  • Create the nova.image.api module that instantiates a driver

  • Create the base image driver class, modeling after the new nova.network.driver class created by the refactor-network-api blueprint code.

  • Move the existing glance code into a subclassed driver

Dependencies

None

Testing

None

Documentation Impact

None

References

None

Creative Commons Attribution 3.0 License

Except where otherwise noted, this document is licensed under Creative Commons Attribution 3.0 License. See all OpenStack Legal Documents.

nova-specs