On last midcycle meetup was decided to make snapshots optional feature.
Features:
- Add new boolean capability 'snapshot_support' to base share driver
so every existing share driver will inherit it. Make value of it be
calculated from the fact of redefinition of three main driver
methods for snapshots 'create_snapshot', 'delete_snapshot' and
'create_share_from_snapshot'.
- Set extra spec 'snapshot_support' with share type creation by default
to 'True'
- Restrict deletion of extra spec 'snapshot_support' that is expected
to exist
- Allow to redefine new extra spec 'snapshot_support'
- Restrict API 'snapshot create' for share created with
share type that has extra spec 'snapshot_support' equal to 'False'.
- Add migration where new extra spec 'snapshot_support' is added
to all share types that do not have it yet.
Partially implements bp snapshots-optional
Change-Id: I069d9e911c7d7a708fa518b38ed10572a45e5f42
af6814f9ca