Autoscaling signals to allow parameter passing for UserData

Registered by Chris Alfonso

When triggering an autoscaling scale-up event a set of user data parameter key/value pairs should be able to be passed and then merged with the resource user data declared in the resource template. When triggering scale-down event a hostname parameter should be able to be passed to specify exactly whish host and associated resources should be deprovisioned.

Blueprint information

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Steve Baker
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(shardy): Thanks for this BP - I think we'll have to create another one to track the creation of a native autoscaling resource, since we probably can't add this functionality to the AWS-compatible resource (I'm assuming that functionality such as you describe doesn't exist in Cloudformation..). Hopefully after the HK summit, we'll have a clearer task-list related to the native autoscaling features, and we can feed this requirement in to that.

(radix): first, this blueprint discusses two separate features, so I think it should be two different blueprints: 1) specify parameters during scale-up, 2) specify units to remove when scaling down. Second, while I have heard some good use cases for #2, #1 is new to me, and my immediate reaction to it is that it's inappropriate for an "autoscaling" system -- it sounds like specifying parameters on scale-up is just "creation of resources", which is very manual.

So I think we should build "specify units to remove on scale-down" into the new autoscaling API and resources, but I think it'd be good to have more use cases and discussion about the parameters-on-scale-up feature.

Gerrit topic:,topic:bp/autoscaling-parameters,n,z

Addressed by:
    ResourceGroup add remove_id to remove_policies


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