[openstack-dev] [Nova] State machines in Nova
harlowja at fastmail.com
Wed Jun 1 15:45:52 UTC 2016
Miles Gould wrote:
> On 31/05/16 21:03, Timofei Durakov wrote:
>> there is blueprint that was approved during Liberty and resubmitted
>> to Newton(with spec).
>> The idea is to define state machines for operations as live-migration,
>> resize, etc. and to deal with them operation states.
> +1 to introducing an explicit state machine - IME they make complex
> logic much easier to reason about. However, think carefully about how
> you'll make changes to that state machine later. In Ironic, this is an
> ongoing problem: every time we change the state machine, we have to
> decide whether to lie to older clients (and if so, what lie to tell
> them), or whether to present them with the truth (and if so, how badly
> they'll break). AIUI this would be a much smaller problem if we'd
> considered this possibility carefully at the beginning.
Do u have any more details (perhaps an 'real-life' example that you can
walk us through) of this and how it played out. It'd be interesting to
hear (I believe it has happened a few times but I've never heard how it
was resolved or the details of it).
> OpenStack Development Mailing List (not for usage questions)
> Unsubscribe: OpenStack-dev-request at lists.openstack.org?subject:unsubscribe
More information about the OpenStack-dev