Azure Functions Docs

Azure Functions Event Grid Triggers

Azure Event Grid is a fully managed event routing service that enables you to easily build applications with an event-driven architecture. Event Grid uses publish-subscribe eventing to loosely couple event producers and event consumers.

Azure Functions can be triggered by events published to Event Grid, allowing you to react to a wide variety of Azure resource events or custom events.

The Event Grid Trigger

The Event Grid trigger for Azure Functions allows your function to execute in response to events published by Event Grid. This is a powerful way to build serverless workflows that respond to changes in your Azure environment or custom events published by your applications.

When an event is received by the function, the trigger deserializes the event data and provides it to your function as an input parameter. You can configure your function to listen for specific event types and sources.

Supported Events

Event Grid supports a wide range of event sources, including:

• Azure Resource Manager: For events related to the creation, modification, or deletion of Azure resources.
• Azure Storage: Blob creation or deletion.
• Azure Event Hubs: New events available in an Event Hub.
• Azure Service Bus: Messages added to a queue or topic.
• Custom Topics: Events published by your own applications.

You can create subscriptions to specific event types from these sources to trigger your Azure Function.

Configuration

To configure an Event Grid trigger for your Azure Function, you typically use the function.json file or attributes in your code (depending on your language runtime).

function.json Example:

{
  "scriptFile": "__init__.py",
  "bindings": [
    {
      "name": "event",
      "type": "eventGridTrigger",
      "direction": "in",
      "topicEndpoint": "{eventGridTopicEndpoint}",
      "keySetting": "{eventGridKeySetting}"
    },
    {
      "name": "outputBlob",
      "type": "blob",
      "direction": "out",
      "path": "output/{rand-guid}-{name}",
      "connection": "AzureWebJobsStorage"
    }
  ]
}

Key Properties:

• name: The name of the input parameter that receives the event data.
• type: Must be eventGridTrigger.
• direction: Must be in.
• topicEndpoint: The endpoint of the Event Grid topic. This is often a setting stored in your application settings.
• keySetting: The name of the app setting that contains the access key for the Event Grid topic.

You'll also need to set up an Event Grid Subscription in Azure that points to your Function App's webhook endpoint.

Code Examples

C# Example:

using Microsoft.Azure.WebJobs;
using Microsoft.Azure.EventGrid.Models;
using Microsoft.Extensions.Logging;

public static class EventGridProcessor
{
    [FunctionName("EventGridTriggerCSharp")]
    public static void Run(
        [EventGridTrigger] EventGridEvent eventGridEvent,
        ILogger log)
    {
        log.LogInformation($"Event received: {eventGridEvent.EventType}");
        log.LogInformation($"Subject: {eventGridEvent.Subject}");
        log.LogInformation($"Data: {eventGridEvent.Data}");
    }
}

Python Example:

import logging
import azure.functions as func

def main(event: func.EventGridEvent):
    logging.info('EventGrid trigger function processed an event.')
    logging.info(f'Subject: {event.subject}')
    logging.info(f'Event Type: {event.event_type}')
    logging.info(f'Data: {event.data}')

JavaScript Example:

module.exports = async function (context, eventGridEvent) {
    context.log(`JavaScript eventgrid trigger function processed an event.`);
    context.log(`Subject: ${eventGridEvent.subject}`);
    context.log(`Event Type: ${eventGridEvent.eventType}`);
    context.log(`Data: ${JSON.stringify(eventGridEvent.data)}`);
};

Advanced Topics