[openstack-dev] [Heat] as-update-policy implementation details

Zane Bitter zbitter at redhat.com
Fri Aug 16 18:16:52 UTC 2013

On 15/08/13 19:14, Chan, Winson C wrote:
> I updated the implementation section of https://wiki.openstack.org/wiki/Heat/Blueprints/as-update-policy on instance naming to support UpdatePolicy where in the case of the LaunchConfiguration change, all the instances need to be replaced and to support MinInstancesInService, the handle_update should create new instances first before deleting old ones in a batch per MaxBatchSize (i.e., group capacity of 2 with MaxBatchSize=2 and MinInstancesInService=2).  Please review as I may not understand the original motivation for the existing scheme in instance naming.  Thanks.

Yeah, I don't think the naming is that important any more. Note that 
physical_resource_name() (i.e. the name used in Nova) now includes a 
randomised component on the end (stackname-resourcename-uniqueid).

So they'll probably look a bit like:


because the instances are now resources inside a nested stack (whose 
name is of the same form).

If we still were subclassing Instance in the autoscaling code to 
override other stuff, I'd suggest overriding physical-resource-name to 
return something like:


(i.e. forget about numbering instances at all), but we're not 
subclassing any more, so I'm not sure if it's worth it.


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