[openstack-dev] [Heat] Order of machines to be terminated during scale down

Jay Lau jay.lau.513 at gmail.com
Wed Nov 26 12:50:04 UTC 2014

The current behavior is not flexible to customer,  I see that we have a
blueprint want to enhance this behavior.


In Use Case section, we have the following:
Use Cases

   1. Users want to use AutoScale without using Heat templates.
   2. Users want to use AutoScale *with* Heat templates.
   3. Users want to scale arbitrary resources, not just instances.
   4. Users want their autoscaled resources to be associated with shared
   resources such as load balancers, cluster managers, configuration servers,
   and so on.
   5. TODO: Administrators or automated processes want to add or remove
   *specific* instances from a scaling group. (one node was compromised or had
   some critical error?)
   6. TODO: Users want to specify a general policy about which resources to
   delete when scaling down, either newest or oldest
   7. TODO: A hook needs to be provided to allow completion or cancelling
   of the auto scaling down of a resource. For example, a MongoDB shard may
   need draining to other nodes before it can be safely deleted. Or another
   example, replica's may need time to resync before another is deleted. The
   check would ensure the resync is done.
   8. *TODO: Another hook should be provided to allow selection of node to
   scale down. MongoDB example again, select the node with the least amount of
   data that will need to migrate to other hosts.*


Item 8 is enabling customer can customize the instance to scale down.


2014-11-26 18:30 GMT+08:00 Pavlo Shchelokovskyy <
pshchelokovskyy at mirantis.com>:

> Maish,
> by default they are deleted in in the same order they were created, FIFO
> style.
> Best regards,
> Pavlo Shchelokovskyy.
> On Wed, Nov 26, 2014 at 12:24 PM, Maish Saidel-Keesing <
> maishsk+openstack at maishsk.com> wrote:
>> In which order are machines terminated during a scale down action in an
>> auto scaling group
>> For example instance 1 & 2 were deployed in a stack. Instances 3 & 4
>> were created as a result of load.
>> When the load is reduced and the instances are scaled back down, which
>> ones will be removed? And in which order?
>> From old to new (1->4) or new to old (4 -> 1) ?
>> Thanks
>> --
>> Maish Saidel-Keesing
>> _______________________________________________
>> OpenStack-dev mailing list
>> OpenStack-dev at lists.openstack.org
>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> --
> Pavlo Shchelokovskyy
> Software Engineer
> Mirantis Inc
> www.mirantis.com
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev


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