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, Optional)
• unprocessedEventThreshold - Average target value to trigger scaling actions. (Default: 64, Optional)
• 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.

💡 The Azure Storage connection string is not compatible with connection string created from a Shared Access Signature.

Authentication Parameters

You can authenticate by using pod identity or connection string authentication.

Connection String Authentication:

• connection - Connection string for the Azure Event Hubs Namespace.

  The following formats are supported.

  • With SharedAccessKey - Endpoint=sb://<sb>.servicebus.windows.net/;SharedAccessKeyName=<key name>;SharedAccessKey=<key value>;EntityPath=<hub-name>.

• storageConnection - Connection string for the Azure Storage Account used to store checkpoint information.

💡 When providing connection, EntityPath is optional. If it is not provided, then eventHubName must be used to provide the name of the Azure Event Hub instance to use inside the namespace.

Pod identity based authentication:

Azure AD Pod Identity or Azure AD Workload Identity providers can be used.

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