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No Event Grid events triggering when uploading files to Azure Blob Storage -- why?

I set up a simple scenario in Azure using a Storage Account, a Function App, and an Event Grid System Trigger. Blob uploads into the Storage Account should cause the Event Grid System Trigger to send a BlobCreated event to trigger the Azure Function.

I can see that the Event Grid System Topic appears to be configured for the correct storage account according to the overview page in the Azure Portal:

Azure Portal.

I have a subscription created for the Event Grid System Topic, and it subscribes to all of the events the storage account can generate as I can see in the Azure Portal. This shows all 6 event types enabled, so I'm not filtering them out.

Details pane.

Despite this, when I upload blobs into a container I created in my storage account and watch for the events to show up in the metrics on my Event Grid System Topic, or see my Azure Function trigger, no events appear to ever be generated. Some interesting points about my storage account which may be worth mentioning are:

  • I am using a premium storage account
  • I am using a private vnet for my storage account

I suspected the network, but to rule that out I changed my storage account back to public and tried again but it didn't change the behavior. From everything I can tell from documentation, this should be working. Any ideas why it isn't?

Solution

  • I work at MS in the SDK team, and I reached to an EventGrid team member directly for opinion:

    I looked into our service logs for last two weeks and I could not find any events for this topic/event-subscription.

    Can you please provide specific time and region when you are uploading/deleting/editing the blobs to help investigating? Also, is this specific to this storage account? Was this working before or this scenario working for other storage accounts? Can you please open a support ticket to handle this properly.

    Thanks! In any doubt on the process, feel free to reply to me, we'll monitor this thread

    [Edit: more info from Storage team]

    We communicated with Azure Storage team and they confirmed that the behavior as described is by design and expected. Here are some additional details from Azure Storage Team:

    The issue is that the customer is using a Premium_LRS StorageV2 account. These accounts only support premium page blobs and premium disks.

    If the customer wants to store block blobs in the premium tier, they need to create a BlockBlobStorage account.

    See subscript 5 in this table: https://learn.microsoft.com/en-us/azure/storage/common/storage-account-overview