Open Stack

On 25/04/14 12:23, Chris Friesen wrote:
>
> I'm looking to add support for server groups to heat.  I've got working
> code, but I thought I'd post the overall design here in case people had
> objections.
>
> Basically, what I propose is to add a "class NovaServerGroup" resource.
>   Currently it would only support a "policy" property to store the
> scheduler policy for the server group.  The scheduler policy would not
> support updating on the fly.

If I correctly understood Mike when he previously talked about this, a 
server group policy is an actual "thing" in Nova with a UUID that gets 
passed to servers when you create them. If that is the case, then +1 for 
this design.

> The "LaunchConfiguration" and "Instance" classes would be extended with
> an optional "ServerGroup" property.  In the "Instance" class if the
> "ServerGroup" property is set then the group name is added to the
> scheduler_hints when building the instance.

-1 for making changes to AWS resources. These only exist for portability 
from/to CloudFormation; if people want to use OpenStack-only features 
then they should use the native resource types.

In the case of autoscaling, I'd say you probably want to add the 
property to e.g. InstanceGroup rather than to the LaunchConfiguration. 
(I guess this will become somewhat academic in the future, as I believe 
the plan for new native autoscaling resources is to have the launch 
configuration defined as part of the scaling group.)

> The "Server" class would be extended with an optional "server_group"
> property.  If it is set then the group name is added to the
> scheduler_hints when building the server.

Given that we already expose the scheduler_hints directly, can you talk 
about why it would be advantageous to have a separate property as well? 
(e.g. syntax would be really finicky?)

cheers,
Zane.