[FEATURE REQ]Add EventGrid AzureFunction Endpoint Support for Container Apps with Native Functions

API Spec link

https://raw.githubusercontent.com/Azure/azure-rest-api-specs/main/specification/eventgrid/resource-manager/Microsoft.EventGrid/preview/2025-04-01-preview /examples/EventSubscriptions_CreateOrUpdateForCustomTopic_AzureFunctionDestination.json

API Spec version

2025-04-01

Please describe the feature.

Description:

Current Situation:
Azure Container Apps now supports native Azure Functions (announced in
https://techcommunity.microsoft.com/blog/appsonazureblog/announcing-native-azure-functions-support-in-azure-container-apps/4414039) with kind: functionapp.
However, EventGrid's AzureFunction endpoint type does not recognize Container Apps as valid Azure Function resources.

Problem:
When attempting to create an EventGrid subscription with an AzureFunction endpoint type pointing to a Container App with native Functions support, the
deployment fails with "Invalid ARM Id" error.

Technical Details:

• Container App with kind: functionapp is properly configured and running Functions
• KEDA scaling rules are successfully configured for the Function App
• Functions runtime environment variables are set correctly
• EventGrid only accepts resource IDs in format: /subscriptions/.../providers/Microsoft.Web/sites/{site}/functions/{function}
• Container Apps use format: /subscriptions/.../providers/Microsoft.App/containerApps/{app}
• Even the latest preview API version (2025-04-01-preview) doesn't support Container Apps

Expected Behavior:
EventGrid should accept Container App resource IDs when the Container App has kind: functionapp set, allowing:
/subscriptions/{subscription}/resourceGroups/{rg}/providers/Microsoft.App/containerApps/{containerApp}/functions/{functionName}

Business Impact:

• Cannot use EventGrid triggers with Container Apps native Functions
• Forces workarounds like manual webhook validation
• Prevents full adoption of Container Apps for Functions workloads
• Creates feature parity gap between traditional Functions and Container Apps Functions

Reproduction Steps:

1. Create Container App with kind: functionapp
2. Deploy Function code with EventGrid trigger
3. Attempt to create EventGrid subscription with AzureFunction endpoint type
4. Receive "Invalid ARM Id" error

Workaround:
Currently must use webhook endpoint type with manual validation handling, which adds complexity and maintenance overhead.

Requested Feature:
Update EventGrid service to recognize and validate Container Apps with kind: functionapp as valid AzureFunction endpoints.

Priority: High - This blocks a key integration scenario for the new native Functions support in Container Apps.

Start with the linked EventGrid 2025-04-01-preview API specification and its AzureFunction destination example. Compare the documented AzureFunction resource ID validation with the requested Microsoft.App containerApps form and kind: functionapp behavior. Done means EventGrid accepts the specified Container App function resource ID and the deployment no longer returns Invalid ARM Id.