Route Blob storage events to a custom web endpoint with Azure CLI

Azure Event Grid is an eventing service for the cloud. In this article, you use the Azure CLI to subscribe to Blob storage events, and trigger the event to view the result.

Typically, you send events to an endpoint that responds to the event, such as a webhook or Azure Function. To simplify the example shown in this article, we send the events to a URL that merely collects the messages. You create this URL by using a third-party tool from Hookbin.

Note

Hookbin is not intended for high throughput usage. The use of this tool is purely demonstrative. If you push more than one event at a time, you might not see all of your events in the tool.

When you complete the steps described in this article, you see that the event data has been sent to an endpoint.

If you don't have an Azure subscription, create a free account before you begin.

Open Azure Cloud Shell

Azure Cloud Shell is a free, interactive shell that you can use to run the steps in this article. Common Azure tools are preinstalled and configured in Cloud Shell for you to use with your account. Just select the Copy button to copy the code, paste it in Cloud Shell, and then press Enter to run it. There are a few ways to open Cloud Shell:

Select Try It in the upper-right corner of a code block. Cloud Shell in this article
Open Cloud Shell in your browser. https://shell.azure.com/bash
Select the Cloud Shell button on the menu in the upper-right corner of the Azure portal. Cloud Shell in the portal

If you choose to install and use the CLI locally, this article requires that you are running the latest version of Azure CLI (2.0.24 or later). To find the version, run az --version. If you need to install or upgrade, see Install Azure CLI 2.0.

If you are not using Cloud Shell, you must first sign in using az login.

Create a resource group

Event Grid topics are Azure resources, and must be placed in an Azure resource group. The resource group is a logical collection into which Azure resources are deployed and managed.

Create a resource group with the az group create command.

The following example creates a resource group named <resource_group_name> in the westcentralus location. Replace <resource_group_name> with a unique name for your resource group.

az group create --name <resource_group_name> --location westcentralus

Create a storage account

To use Blob storage events, you need either a Blob storage account or a General Purpose v2 storage account. General Purpose v2 (GPv2) are storage accounts that support all features for all storage services, including Blobs, Files, Queues, and Tables. A Blob storage account is a specialized storage account for storing your unstructured data as blobs (objects) in Azure Storage. Blob storage accounts are like general-purpose storage accounts and share all the great durability, availability, scalability, and performance features that you use today including 100% API consistency for block blobs and append blobs. For applications requiring only block or append blob storage, we recommend using Blob storage accounts.

Note

Availability for Storage events is tied to Event Grid availability and will become available in other regions as Event Grid does.

Replace <storage_account_name> with a unique name for your storage account, and <resource_group_name> with the resource group you created earlier.

az storage account create \
  --name <storage_account_name> \
  --location westcentralus \
  --resource-group <resource_group_name> \
  --sku Standard_LRS \
  --kind BlobStorage \
  --access-tier Hot

Create a message endpoint

Before subscribing to the topic, let's create the endpoint for the event message. Rather than write code to respond to the event, let's create an endpoint that collects the messages so you can view them. Hookbin is a third-party tool that enables you to create an endpoint, and view requests that are sent to it. Go to Hookbin and click Create New Endpoint. Copy the bin URL, because you need it when subscribing to the topic.

Subscribe to your storage account

You subscribe to a topic to tell Event Grid which events you want to track. The following example subscribes to the storage account you created, and passes the URL from Hookbin as the endpoint for event notification. Replace <event_subscription_name> with a unique name for your event subscription, and <endpoint_URL> with the value from the preceding section. By specifying an endpoint when subscribing, Event Grid handles the routing of events to that endpoint. For <resource_group_name> and <storage_account_name>, use the values you created earlier.

storageid=$(az storage account show --name <storage_account_name> --resource-group <resource_group_name> --query id --output tsv)

az eventgrid event-subscription create \
  --resource-id $storageid \
  --name <event_subscription_name> \
  --endpoint <endpoint_URL>

Trigger an event from Blob storage

Now, let's trigger an event to see how Event Grid distributes the message to your endpoint. First, let's configure the name and key for the storage account, then we create a container, then create and upload a file. Again, use the values for <storage_account_name> and <resource_group_name> you created earlier.

export AZURE_STORAGE_ACCOUNT=<storage_account_name>
export AZURE_STORAGE_ACCESS_KEY="$(az storage account keys list --account-name <storage_account_name> --resource-group <resource_group_name> --query "[0].value" --output tsv)"

az storage container create --name testcontainer

touch testfile.txt
az storage blob upload --file testfile.txt --container-name testcontainer --name testfile.txt

You have triggered the event, and Event Grid sent the message to the endpoint you configured when subscribing. Browse to the endpoint URL that you created earlier. Or, click refresh in your open browser. You see the event you just sent.

[{
  "topic": "/subscriptions/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx/resourceGroups/myrg/providers/Microsoft.Storage/storageAccounts/myblobstorageaccount",
  "subject": "/blobServices/default/containers/testcontainer/blobs/testfile.txt",
  "eventType": "Microsoft.Storage.BlobCreated",
  "eventTime": "2017-08-16T20:33:51.0595757Z",
  "id": "4d96b1d4-0001-00b3-58ce-16568c064fab",
  "data": {
    "api": "PutBlockList",
    "clientRequestId": "d65ca2e2-a168-4155-b7a4-2c925c18902f",
    "requestId": "4d96b1d4-0001-00b3-58ce-16568c000000",
    "eTag": "0x8D4E4E61AE038AD",
    "contentType": "text/plain",
    "contentLength": 0,
    "blobType": "BlockBlob",
    "url": "https://myblobstorageaccount.blob.core.windows.net/testcontainer/testblob1.txt",
    "sequencer": "00000000000000EB0000000000046199",
    "storageDiagnostics": {
      "batchId": "dffea416-b46e-4613-ac19-0371c0c5e352"
    }
  },
  "dataVersion": "",
  "metadataVersion": "1"
}]

Clean up resources

If you plan to continue working with this storage account and event subscription, do not clean up the resources created in this article. If you do not plan to continue, use the following command to delete the resources you created in this article.

Replace <resource_group_name> with the resource group you created above.

az group delete --name <resource_group_name>

Next steps

Now that you know how to create topics and event subscriptions, learn more about Blob storage Events and what Event Grid can help you do: