Provide CloudEvents when scaling workload(s) from/to 0

[tomkerkhove]

Proposal

Event Types

• keda.workload.scaletozero.v1
• keda.workload.scalefromzero.v1

Payload:

{
    "specversion" : "1.0",
    "type" : "keda.workload.scaletozero.v1",
    "subject" : "/{kubernetes-cluster-name}/{namespace}/workload/{resource-name}/",
    "time" : "2018-04-05T17:31:00Z",
    "datacontenttype" : "application/json",
    "data" : {
      "scaleTarget": {
         "name": "sample-workload",
         "apiVersion": "Deployment",
         "kind": "apps/v1",
      }
   }
}

Use-Case

Allow end-users to get notified when workloads are scaling to/from 0.

Anything else?

Relates to #479