Create and route custom events with Azure CLI and Event Grid

Azure Event Grid is an eventing service for the cloud. In this article, you use the Azure CLI to create a custom topic, subscribe to the topic, 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. However, to simplify this article, you send the events to a URL that merely collects the messages. You create this URL by using an open source, third-party tool called RequestBin.

Note

RequestBin is an open source tool that is not intended for high throughput usage. The use of the tool here 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 are finished, you see that the event data has been sent to an endpoint.

Event data

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

Launch Azure Cloud Shell

The Azure Cloud Shell is a free Bash shell that you can run directly within the Azure portal. It has the Azure CLI preinstalled and configured to use with your account. Click the Cloud Shell button on the menu in the upper-right of the Azure portal.

Cloud Shell

The button launches an interactive shell that you can use to run the steps in this topic:

Screenshot showing the Cloud Shell window 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 (2.0.14 or later). To find the version, run az --version. If you need to install or upgrade, see Install Azure CLI 2.0.

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 gridResourceGroup in the westus2 location.

az group create --name gridResourceGroup --location westus2

Create a custom topic

A topic provides a user-defined endpoint that you post your events to. The following example creates the topic in your resource group. Replace <topic_name> with a unique name for your topic. The topic name must be unique because it is represented by a DNS entry. For the preview release, Event Grid supports westus2 and westcentralus locations.

az eventgrid topic create --name <topic_name> -l westus2 -g gridResourceGroup

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. RequestBin is an open source, third-party tool that enables you to create an endpoint, and view requests that are sent to it. Go to RequestBin, and click Create a RequestBin. Copy the bin URL, because you need it when subscribing to the topic.

Subscribe to a topic

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

az eventgrid topic event-subscription create --name <event_subscription_name> \
  --endpoint <URL_from_RequestBin> \
  -g gridResourceGroup \
  --topic-name <topic_name>

Send an event to your topic

Now, let's trigger an event to see how Event Grid distributes the message to your endpoint. First, let's get the URL and key for the topic. Again, use your topic name for <topic_name>.

endpoint=$(az eventgrid topic show --name <topic_name> -g gridResourceGroup --query "endpoint" --output tsv)
key=$(az eventgrid topic key list --name <topic_name> -g gridResourceGroup --query "key1" --output tsv)

To simplify this article, we have set up sample event data to send to the topic. Typically, an application or Azure service would send the event data. The following example gets the event data:

body=$(eval echo "'$(curl https://raw.githubusercontent.com/Azure/azure-docs-json-samples/master/event-grid/customevent.json)'")

If you echo "$body" you can see the full event. The data element of the JSON is the payload of your event. Any well-formed JSON can go in this field. You can also use the subject field for advanced routing and filtering.

CURL is a utility that performs HTTP requests. In this article, we use CURL to send the event to our topic.

curl -X POST -H "aeg-sas-key: $key" -d "$body" $endpoint

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

[{
  "id": "1807",
  "eventType": "recordInserted",
  "subject": "myapp/vehicles/motorcycles",
  "eventTime": "2017-08-10T21:03:07+00:00",
  "data": {
    "make": "Ducati",
    "model": "Monster"
  },
  "topic": "/subscriptions/{subscription-id}/resourceGroups/{resource-group}/providers/Microsoft.EventGrid/topics/{topic}"
}]

Clean up resources

If you plan to continue working with this event, 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.

az group delete --name gridResourceGroup

Next steps

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