Glance in Multidatacenter

Hi Nati-san!

OK, so doing cross-datacenter sync'ing is not currently fully supported in Glance. However, we are adding functionality in the Essex timeframe that should be able to fulfill this functionality. It will depend partly on the underlying storage system that Glance is using. If you use Swift, you can do cross-container sync'ing using the methods described here:

http://swift.openstack.org/overview_container_sync.html

After that is set up, then objects that are added to Glance using a Swift backend, will sync to containers located in separate clusters. But the Glance Registry will still only have a single URI location for the image file, and will not be able to tell a client if there are alternate locations to retrieve the image (from the sync'd Swift containers).

The following blueprint in Glance is designed to overcome this problem, by having the registry server supply a /images/<ID>/replicas resource that can return those alternate storage locations:

https://blueprints.launchpad.net/glance/+spec/image-replicas

We hope to get this blueprint completed around the E3 milestone or earlier.

Cheers!
-jay