Stack snapshots don't translate to volume snapshots

[Tobias Rydberg]

If a Heat stack contains Cinder volumes, then openstack stack snapshot doesn't create a snapshot of those volumes as one would expect, but instead tries to create a backup. That means that it relies on the availability of the cinder-backup service, and if an operator does not deploy that, they effectively break Heat's snapshot capability.

What would be expect instead is that Heat would just take a Cinder snapshot when instructed to do a volume snapshot, or at least have a way to configure Heat to do so, even if we were to stick with the rather illogical current behavior.

[Zane Bitter (zaneb)]

I believe this was intentional. From memory it's because snapshots get deleted if the volume is deleted, but backups do not. So even though it makes the naming a little weird, there are circumstances where you wouldn't be able to restore the stack snapshot if it relied on volume snapshots.