Open Stack

Hi all,

I started working on the stack snapshot blueprint [1] and wrote a first series of patches [2] to get a feeling of what's possible. I have a couple of related design questions though:

 * Is a stack snapshot independent of the stack? That's the way I chose for my patches, you start with a stack, but then you can show and delete snapshots independently. The main impact will be how restoration works: is restoration an update action on a stack towards a specific state, or a creation action with backup data?

 * Consequently, should be use volume backups (which survive deleting of the original volumes) or volume snapshots (which don't). If the snapshot is dependent of the stack, then we can use the more efficient snapshot operation. But backup is also an interesting use-case, so should it be another action completely?


[1] https://blueprints.launchpad.net/heat/+spec/stack-snapshot

[2] https://review.openstack.org/#/q/status:open+project:openstack/heat+branch:master+topic:bp/stack-snapshot,n,z

Thanks,

-- 
Thomas