Cloned from launchpad blueprint https://blueprints.launchpad.net/glance/+spec/image-error-state-management.

Description:

Instead of "killing" an image when something goes wrong during data upload, we need a good way to make it obvious the image failed to upload and notify the user. I propose we add an image error state and take a deeper look at image states in general.

There are a couple of use cases where this is important.

- Snapshots through nova
 When a snapshot fails the image could be set to ERROR instead of being deleted/killed. This way users can see that a snapshot failed.

- Copy-from images
 If a copy from image fails during the data copying by the async worker then there is no way for a user to know it failed and it would be unintuitive for the image resource to disappear.

- Failed uploads
 In addition to error responses from Glance when an upload fails, it would be nice for that image resource to not be deleted automatically and have a way for the user to know it had errored. This way uploads could be retried without having to create a whole new image entity.

Specification URL (additional information):

None