How to fetch events from eventhub from a timer enabled azure function? - azure

Question

I am working with Azure Event Hubs. My requirement is to fetch the events from Azure Event Hub, using azure function on a daily basis. Basically my azure function will be timer enabled. It should be able to fetch the data from azure event hubs. Is there a mechanism for this ?
I am aware that we can trigger a azure function whenever an event is received at event hub. This i don't want as the function will execute n number of time. I want to just fetch the events on a daily basis.

Answer 1

You can still create a timer triggered function and create consumer clients in your code to receive events. See sample code below. Let me know if you have any questions.
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Azure.Messaging.EventHubs.Consumer;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;
namespace FunctionApp7
{
public static class Function1
{
const string EventHubsConnectionString = "your connection string";
const string EventHubName = "evethub name";
const string ConsumerGroupName = "cgname";
[FunctionName("Function1")]
public static void Run([TimerTrigger("0 */5 * * * *")]TimerInfo myTimer, ILogger log)
{
log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}");
// You better dissover partitions by eventhub client. I am just hardcoding them here for now.
var partitions = new List<string> { "0", "1" };
var receiveTasks = new List<Task>();
foreach(var p in partitions)
{
receiveTasks.Add(ReadEventsFromPartition(p));
}
// Wait until all reads complete.
Task.WhenAll(receiveTasks);
}
public static async Task ReadEventsFromPartition(string partitionId)
{
await using (var consumer = new EventHubConsumerClient(ConsumerGroupName, EventHubsConnectionString, EventHubName))
{
EventPosition startingPosition = EventPosition.FromOffset(CheckpointStore.ReadOffsetForPartition(partitionId));
long lastOffset = -1;
await foreach (PartitionEvent receivedEvent in consumer.ReadEventsFromPartitionAsync(partitionId, startingPosition))
{
// Process received events here.
// Break if no events left.
if (receivedEvent.Data == null)
{
break;
}
lastOffset = receivedEvent.Data.Offset;
}
// Persist last event's offset so we can continue reading from this position next time function is triggered.
if (lastOffset != -1)
{
// Write offset into some durable store.
CheckpointStore.WriteOffsetForPartition(partitionId, lastOffset);
}
}
}
}
}