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Scale applications based on Azure Event Hubs.

Availability: v1.0+ Maintainer: Community

Notice

As of now, the Event Hub scaler only supports reading checkpoints from Blob Storage, as well as scaling only Event Hub applications written in C#, Java, Python or created with Azure Functions.

Trigger Specification

This specification describes the azure-eventhub trigger for Azure Event Hubs.

triggers:
- type: azure-eventhub
  metadata:
    connectionFromEnv: EVENTHUB_CONNECTIONSTRING_ENV_NAME
    storageConnectionFromEnv: STORAGE_CONNECTIONSTRING_ENV_NAME
    consumerGroup: $Default
    unprocessedEventThreshold: '64'
    blobContainer: 'name_of_container'

Parameter list:

  • connectionFromEnv - Name of the environment variable your deployment uses to get the connection string appended with EntityPath=<event_hub_name>
  • storageConnectionFromEnv - Name of the environment variable that provides connection string for Azure Storage Account to store checkpoint. As of now the Event Hub scaler only reads from Azure Blob Storage.
  • consumerGroup - Consumer group of event hub consumer. (default: $default)
  • unprocessedEventThreshold - : Average target value to trigger scaling actions. (default: 64)
  • blobContainer - Container name to store checkpoint. This is needed when a using an Event Hub application written in dotnet or java, and not an Azure function

Authentication Parameters

The common way of authenticating to Azure Event Hub is by using the connection string. However, you can use Pod Identity if you host your cluster in Azure AKS, and if have configured it to support Pod Identity.

To use Pod Identity, you have to add a TriggerAuthentication and configure it to use Pod Identity like so:

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

When you do so, the Event Hub scaler will depend on the existence of two configurations you have to provide: eventHubNamespace and eventHubName.

Example

apiVersion: keda.sh/v1alpha1
kind: ScaledObject
metadata:
  name: azure-eventhub-scaledobject
  namespace: default
spec:
  scaleTargetRef:
    name: azureeventhub-function
  triggers:
  - type: azure-eventhub
    metadata:
      # Required
      storageConnectionFromEnv: AzureWebJobsStorage
      # Required if not using Pod Identity
      connectionFromEnv: EventHub
      # Required if using Pod Identity
      eventHubNamespace: AzureEventHubNameSpace
      eventHubName: NameOfTheEventHub
# Optional
      consumerGroup: $Default # default: $Default
      unprocessedEventThreshold: '64' # default 64 events.
      blobContainer: ehcontainer


Currently available scalers for KEDA