System Topics in Azure Event Grid: Setup and Management Explained

Have you ever wondered how Azure services notify your apps when something changes? Instead of constantly checking for updates, Azure Event Grid pushes events the moment they occur. At the center of this process are system topics, which act as channels for event delivery. They represent the event streams from supported Azure services and make it possible to route those events to different endpoints.

By working with system topics, you can subscribe to events, send them to destinations like Functions or Logic Apps, and manage everything directly in the Azure portal. This guide will show you what system topics are, how to create them, view them, and remove them when they’re no longer needed.

What is a System Topic?

A system topic is a special Event Grid resource that represents the flow of events from an Azure service. Whenever a supported resource, such as a Storage Account or Event Hub, is configured for event delivery, a system topic is created. This topic organizes and standardizes events so they can be delivered to chosen endpoints.

For example, enabling events on a Storage Account automatically generates a system topic. You can then connect that topic to multiple destinations, like Azure Functions, Logic Apps, or Webhooks. System topics can be created in two ways: automatically while setting up an event subscription or manually through the portal. Once created, they behave like other Azure resources and can be tagged, monitored, or deleted when no longer needed.

Create a System Topic

1. In the Azure portal, type Event Grid System Topics in the search bar and select it.

2. On the page, choose + Create.

3. On the Create Event Grid System Topic screen, provide the following:
   
   • Select the subscription where the resource is located.
   • Pick a resource group for the system topic.
     
   • Enter a name for the topic.
     
   • Select the topic type (for example, here i have selected: Storage Accounts Blob & GPv2).
     
   • Choose the resource you want to connect.

4. Select Review + Create to check the details.
   
5. Click Create to finish deployment.

6. Once complete, select Go to resource to view the new system topic.

View System Topics

1. Sign in to the Azure portal.
   
2. In the search bar, enter Event Grid System Topics and select it.

3. A list of available system topics appears.

4. Click on a topic name to open its details.

From the details page, you can view:

• Source: the Azure resource that generates the events.
  
• Source type: the type of resource (for example, Microsoft.Storage.StorageAccounts).
  
• Event subscriptions linked to that system topic.
  

Delete a System Topic

1. In the Azure portal, go to Event Grid System Topics.
   
2. From the list, choose the topic you want to remove.
   
3. On its details page, select Delete.

4. Confirm the deletion when prompted.
   

Note: Deleting a system topic also removes any event subscriptions associated with it.

Summary

System topics are the backbone of event handling in Azure Event Grid. They define the event source, standardize event delivery, and serve as the place to manage subscriptions. You can create them automatically when setting up an event subscription or manually through the portal. Once created, they can be viewed, tagged, or deleted when no longer needed.

By managing system topics effectively, you can ensure events flow reliably between Azure services and your applications.