How do i format the endpoint URL? - Trigger Azure functions using event subscriptions using bicep

Question

Hi,

I have followed this approach and have had success setting this up via the portal. However, when attempting the same using Bicep, the failure is at the point of creating the Event Grid subscription.
I receive a generic error but believe its to do with the endpointUrl:

{"code":"DeploymentFailed","target":"/subscriptions/xyz/resourceGroups/rg1/providers/Microsoft.Resources/deployments/blob-event-subscription","message":"At least one resource deployment operation failed. Please list deployment operations for details. Please see https://aka.ms/arm-deployment-operations for usage details.","details":[{"code":"BadRequest","message":""}]}}

Here is an example of the eventSubscription bicep code.

resource eventSubscription 'Microsoft.EventGrid/systemTopics/eventSubscriptions@2023-12-15-preview' = {
  parent: systemTopic
  name: eventSubName
  properties: {
    eventDeliverySchema:'EventGridSchema'
    destination: {
      properties: {
        endpointUrl: endpoint
      }
      endpointType: 'WebHook'
    }
    filter: {
      includedEventTypes: [
        'Microsoft.Storage.BlobCreated'
      ]
    }
  }
}

The format of my endpoint URL is as follows:

https://<FUNCTION_APP_NAME>.azurewebsites.net/runtime/webhooks/blobs?functionName=Host.Functions.Function1&code=<BLOB_EXTENSION_KEY>

As mentioned above, this works if setting it up via azure portal, and I require guidance when it comes to the creating the subscription using bicep.

Kind regards,

Adam Evans

Answer 1

@Adam Evans could you please try the below Bicep template for creating an Azure Function with an Event Grid Blob Trigger

please refer: https://learn.microsoft.com/en-us/azure/templates/microsoft.eventgrid/eventsubscriptions?pivots=deployment-language-bicep

param storageAccountName string
param functionAppName string
param location string = resourceGroup().location

resource storageAccount 'Microsoft.Storage/storageAccounts@2021-04-01' = {
  name: storageAccountName
  location: location
  sku: {
    name: 'Standard_LRS'
  }
  kind: 'StorageV2'
}

resource functionApp 'Microsoft.Web/sites@2021-02-01' = {
  name: functionAppName
  location: location
  kind: 'functionapp'
  properties: {
    serverFarmId: 'YOUR_APP_SERVICE_PLAN_ID'
    siteConfig: {
      appSettings: [
        {
          name: 'AzureWebJobsStorage'
          value: storageAccount.properties.primaryEndpoints.blob
        }
        {
          name: 'FUNCTIONS_EXTENSION_VERSION'
          value: '~3'
        }
        {
          name: 'WEBSITE_NODE_DEFAULT_VERSION'
          value: '~14'
        }
      ]
    }
  }
}

resource eventGridSubscription 'Microsoft.EventGrid/eventSubscriptions@2021-06-01-preview' = {
  name: 'blob-created-subscription'
  scope: storageAccount
  properties: {
    destination: {
      endpointType: 'AzureFunction'
      properties: {
        resourceId: functionApp.id
      }
    }
    filter: {
      includedEventTypes: [
        'Microsoft.Storage.BlobCreated'
      ]
    }
  }
}

This template creates a storage account, a function app, and an Event Grid subscription that triggers the function app when a blob is created in the storage account. You will need to replace 'YOUR_APP_SERVICE_PLAN_ID' with the ID of your App Service plan.

do let me know incase of further queries, I would be happy to assist you.