[openstack-dev] [heat] Rolling upgrades vs. duplication of prop data

Crag Wolfe cwolfe at redhat.com
Thu Jan 5 16:41:51 UTC 2017


I have a patch[1] to support the de-duplication of resource properties
data between events and resources. In the ideal rolling-upgrade world,
we would be writing data to the old and new db locations, only reading
from the old in the first release (let's assume Ocata). The problem is
that in this particular case, we would be duplicating a lot of data, so
[1] for now does not take that approach. I.e., it is not rolling-upgrade

So, we need to decide what to do for Ocata:

A. Support assert:supports-upgrade[2] and resign ourselves to writing
duplicated resource prop. data through Pike (following the standard
strategy of write to old/new and read from old, write to old/new and
read from new, write/read from new over O,P,Q).

B. Push assert:supports-upgrade back until Pike, and avoid writing
resource prop. data in multiple locations in Ocata.

C. DB triggers.

I vote for B. I'm pretty sure there is not much support for C (count me
in that group :), but throwing it out there just in case.



[1] https://review.openstack.org/#/c/363415/

[2] https://review.openstack.org/#/c/407989/

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