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Event Hubs¶

Consume high-throughput event streams with the Event Hubs trigger and publish events with the output binding in the .NET isolated worker model.

flowchart TD
    A[Event Producers] --> B[(Event Hub Partitions)]
    B --> C[EventHubTrigger Function]
    C --> D[Downstream Store]
    C --> E[EventHubOutput]

Topic/Command Groups¶

Batch trigger + output binding¶

Delivering an array of events per invocation maximizes throughput. Keep the handler idempotent because delivery is at-least-once.

[Function("ProcessTelemetry")]
[EventHubOutput("downstream", Connection = "EventHubConnection")]
public string[] ProcessTelemetry(
    [EventHubTrigger("telemetry", Connection = "EventHubConnection",
        ConsumerGroup = "$Default")] string[] events,
    FunctionContext context)
{
    var logger = context.GetLogger("ProcessTelemetry");
    logger.LogInformation("Batch size: {Count}", events.Length);

    foreach (var evt in events)
    {
        // Keep processing idempotent.
        logger.LogInformation("Processing event: {Event}", evt);
    }

    return events;
}

Identity-based connection¶

Use a setting prefix with __fullyQualifiedNamespace and grant the managed identity the Azure Event Hubs Data Receiver (and Data Sender for output) role:

az functionapp config appsettings set \
  --name $APP_NAME \
  --resource-group $RG \
  --settings "EventHubConnection__fullyQualifiedNamespace=$NAMESPACE.servicebus.windows.net"

| Command/Parameter | Purpose | | --- | --- | | az functionapp config appsettings set | Add or update application settings on the function app. | | --name | Name of the target resource. | | --resource-group | Resource group that contains the resource. | | --settings | Key=value application settings to apply. |

Host settings and checkpointing¶

{
  "version": "2.0",
  "extensions": {
    "eventHubs": {
      "maxEventBatchSize": 100,
      "batchCheckpointFrequency": 1,
      "prefetchCount": 300
    }
  }
}

Review Matrix¶

Review area	Page-specific check
Scope	Confirm the guidance applies to Event Hubs trigger and output bindings.
Source basis	Validate the recommendation against the Microsoft Learn sources in this page.
Evidence	Capture command output, portal state, metrics, logs, or screenshots before treating the result as proven.

See Also¶

Sources¶