Creating Eventgrid subscription using ARM on Function endpoint - azure

Question

I'm trying to create an Eventgrid subscription on an Azure Storage Account using an ARM template. Manually creating it in the Portal and going to the advanced settings yielded me the template below. I further added the required template items such as schema to it, but it keeps yielding me errors. I've tried looking online for similar templates, but can't seem to find any using the "endpointType": "AzureFunction". Also within the Resource Explorer there's no mention of the deployment to further help me along.
Anybody can help me out what is wrong?
The template as generated during creation from the portal:
{
"name": "test123",
"properties": {
"topic": "/subscriptions/<guid>/resourceGroups/<myGroup>/providers/Microsoft.Storage/storageAccounts/<myStorageAccount>",
"destination": {
"endpointType": "AzureFunction",
"properties": {
"resourceId": "/subscriptions/<guid>/resourceGroups/<myGroup>/providers/Microsoft.Web/sites/<myFunctionsApp>/functions/<myFunction>",
"maxEventsPerBatch": 1,
"preferredBatchSizeInKilobytes": 64
}
},
"filter": {
"includedEventTypes": [
"Microsoft.Storage.BlobCreated"
],
"advancedFilters": [
{
"operatorType": "StringContains",
"key": "Subject",
"values": [
"-original"
]
}
]
},
"labels": [],
"eventDeliverySchema": "EventGridSchema"
}
}
The full template:
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
},
"resources": [
{
"name": "test123",
"type": "Microsoft.EventGrid/eventSubscriptions",
"apiVersion": "2020-01-01-preview",
"location": "westeurope",
"properties": {
"topic": "/subscriptions/<guid>/resourceGroups/<myGroup>/providers/Microsoft.Storage/storageAccounts/<myStorageAccount>",
"destination": {
"endpointType": "AzureFunction",
"properties": {
"resourceId": "/subscriptions/<guid>/resourceGroups/<myGroup>/providers/Microsoft.Web/sites/<myFunctionsApp>/functions/<myFunction>",
"maxEventsPerBatch": 1,
"preferredBatchSizeInKilobytes": 64
}
},
"filter": {
"includedEventTypes": [
"Microsoft.Storage.BlobCreated"
],
"advancedFilters": [
{
"operatorType": "StringContains",
"key": "Subject",
"values": [
"-original"
]
}
]
},
"labels": [
],
"eventDeliverySchema": "EventGridSchema"
}
}
]
}
The error:
The specified topic property does not match the expected topic from the event subscription scope

Answer 1

I've been trying to do the exact same thing by any option in the Azure tool chain (ARM Template/CLI/REST). I looked at the Portal's calls and found it is using the 2020-01-01-preview EventGrid API that you show.
After some testing I can confirm the new API allows deploying a subscription with an EndpointType of AzureFunction like so:
{
"name": "[concat(variables('eventDomainName'), '/Microsoft.EventGrid/', variables('subscriptionName'))]",
"type": "Microsoft.EventGrid/domains/providers/eventSubscriptions",
"location": "[variables('location')]",
"apiVersion": "2020-01-01-preview",
"properties": {
"destination": {
"endpointType": "AzureFunction",
"properties": {
"resourceId": "[resourceId('Microsoft.Web/sites/functions/', parameters('functionAppName'), parameters('functionName'))]"
}
},
"filter": "[parameters('subscriptionProperties').filter]"
}
}
It seems that your problem is unrelated to trying to target the AzureFunction and you're using the right API version so it doesnt seem to be that.
I think the problem is your "Type" value. I think it should be in this format: //providers/eventSubscriptions
So it would be Microsoft.Storage/storageAccounts/providers/eventSubscriptions.

Answer 2

I don't believe there is a separate endpointType of AzureFunction as documented. It is simply a special case of a webhook handler.
This GitHub Repo contains a sample ARM Template that you can refer to. Here is the exact snippet that you would need
...
"destination": {
"endpointType": "WebHook",
"properties": {
"endpointUrl": "[concat(variables('functionUrl'), listKeys(resourceId('Microsoft.Web/sites/host/', variables('functionAppName'), 'default'),'2016-08-01').systemkeys.eventgrid_extension)]"
}
}
...