CloudEvent Support

CloudEvent Support ^{Click here for latest}

Experimental support for cloud events

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Subscribing to events with `CloudEventSource`

CloudEventSource resource can be used in KEDA for subscribing to events that are emitted to the user’s defined CloudEvent sink.

📝 Event will be emitted to both Kubernetes Events and CloudEvents Destination if CloudEventSource resource is created.

Here is a the schema of the CloudEventSource CRD:

apiVersion: eventing.keda.sh/v1alpha1
kind: CloudEventSource
metadata:
  name: {cloud-event-name}
spec:
  clusterName: {cluster-name} #Optional. Will be used in the source/subject to specify where the event comes from. The default value is 'kubernetes-default' and it can also be set during the installation of KEDA with --k8sClusterName. This one will overwrite others if set.
  authenticationRef: 
    name: {trigger-authentication-name} #Optional. Used to reference a `TriggerAuthentication` for authentication. 
    kind: TriggerAuthentication # Optional. Used to choose the authentication scopes. https://keda.sh/docs/latest/concepts/authentication/#authentication-scopes-namespace-vs-cluster
  destination:
    http:
      uri: http://foo.bar
    azureEventGridTopic:
      endpoint: https://my-topic.eastus-1.eventgrid.azure.net/api/events

  eventSubscription: #Optional. Submit included/excluded event types will filter events when emitting events. 
    includedEventTypes: #Optional. Only events in this section will be emitted.
    - keda.scaledobject.failed.v1
    excludedEventTypes: #Optional. Events in this section will not be emitted.       
    - keda.scaledobject.ready.v1

In general, an event emitted by KEDA would fundamentally come down to the following structure:

{
    "specversion" : "1.0",
    "type" : "com.cloudeventsource.keda",
    "source" : "/{cluster-name}/{keda-namespace}/keda",
    "subject" : "/{cluster-name}/{namespace}/{object-type}/{object-name}",
    "id" : "<guid>",
    "time" : "2018-04-05T17:31:00Z",
    "datacontenttype" : "application/json",
    "data" : {
      "reason":"<event-reason>",
      "message":"<event-message>"
   }
}

Scopes: Namespace vs. Cluster

Each CloudEventSource is defined in one namespace and will only subscribe to events inside that namespace. If you want to subscribe to events in all namespaces, you can instead create a ClusterCloudEventSource resource.

Defining a ClusterCloudEventSource works almost identically to a CloudEventSource, except there is no metadata.namespace value:

apiVersion: keda.sh/v1alpha1
kind: ClusterCloudEventSource
metadata:
  name: {cluster-cloudeventsource-name}
spec:
  # As before ..

Event Sinks

There will be multiple types of destination to emit KEDA events to.

Here is an overview of the supported destinations:

HTTP endpoint.
Azure Event Grid endpoint.

HTTP endpoint

  destination:
    http:
      uri: http://foo.bar  #An http endpoint that can receive cloudevent

Azure Event Grid

  destination:
    azureEventGrid:
      endpoint: foo.bar #endpoint from AzureEventGrid Topic

Authentication information must be provided by using authenticationRef which allows you to provide the access key or managed identity for Azure Event Grid authentication by providing a TriggerAuthentication.

Here is an overview of the supported authentication types:

Connection String Authentication

accessKey - Access key string for the Azure Event Grid connection auth.

Pod identity based authentication

Azure AD Workload Identity provider can be used.

apiVersion: keda.sh/v1alpha1
kind: TriggerAuthentication
metadata:
  name: nameOfTriggerAuth
  namespace: default
spec:
  podIdentity:
    provider: azure-workload

Event Filter

You can include filter(s) to define what event types you are interested in, or want to ignore. This is done by using includedEventTypes or excludedEventTypes respectively for a given sink.

eventSubscription: #Optional. Submit included/excluded event types will filter events when emitting events. 
  includedEventTypes: #Optional. Only events in this section will be emitted.
  - keda.scaledobject.failed.v1
  excludedEventTypes: #Optional. Events in this section will not be emitted.       
  - keda.scaledobject.ready.v1

Supported Event List

Event Type	Scenario Description
`keda.scaledobject.ready.v1`	On the first time a ScaledObject is ready, or if the previous ready condition status of the object was `Unknown` or `False`
`keda.scaledobject.failed.v1`	If the check validation for a ScaledObject fails
`keda.scaledobject.removed.v1`	When a ScaledObject is deleted

Subscribing to events with CloudEventSource