ARM implicitly created Event Grid System topic .How Event grid subscription attach to Custom Event gird topic - azure-eventgrid

Question

I have facing issue on deploying a resources via ARM . I have 2 queries .
Query 1 .
Why this below Linked ARM implicitly created Event Grid System Topic This Linked ARM is only used to get trigger URL of azure function
{
"$schema": "https://schema.management.azure.com/schemas/2015-01-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"functionAppName": {
"type": "String"
}
},
"variables": {
"sitesWebApiVersion": "2016-08-01"
},
"resources": [],
"outputs": {
"triggerUrl": {
"type": "String",
"value": "[listsecrets(resourceId('Microsoft.Web/sites/functions', parameters('functionAppName'), 'NPEventGridDataProcessor'), variables('sitesWebApiVersion')).trigger_url]"
}
}
}
Query2
In ARM how I create Event Subscription that attach to explicitly created custom Event Topic. As see the below the master ARM code snippet , event subscription attach unwanted to the Event Grid System Topic . But I want to add it on Custom Event Grid topic .
{
"apiVersion": "2020-06-01",
"scope": "[format('Microsoft.EventGrid/topics/{0}', variables('eventGridName'))]",
"name": "[variables('eventGridSubwebhookName')]",
"type": "Microsoft.EventGrid/eventSubscriptions",
"tags": {
"displayName": "Webhook Subscription"
},
"dependsOn": [
"[resourceId('Microsoft.EventGrid/topics/', variables('eventGridName'))]",
"[resourceId('Microsoft.Resources/deployments/', variables('hackForGettingTriggerUrl'))]"
],
"properties": {
"destination": {
"endpointType": "WebHook",
"properties": {
"endpointUrl": "[reference(variables('hackForGettingTriggerUrl')).outputs.triggerUrl.value]"
}
}
}
}
]

Answer 1

If you want to create event gird subscription for custom topic, please refer to the following template
"resources": [
{
"type": "Microsoft.EventGrid/topics",
"apiVersion": "2020-06-01",
"name": "[parameters('eventGridTopicName')]",
"location": "[parameters('location')]"
},
{
"type": "Microsoft.EventGrid/eventSubscriptions",
"apiVersion": "2020-06-01",
"scope": "[format('Microsoft.EventGrid/topics/{0}', parameters('eventGridTopicName'))]",
"name": "[parameters('eventGridSubscriptionName')]",
"properties": {
"destination": {
"endpointType": "WebHook",
"properties": {
"endpointUrl": "[parameters('eventGridSubscriptionUrl')]"
}
}
},
"dependsOn": [
"[resourceId('Microsoft.EventGrid/topics', parameters('eventGridTopicName'))]"
]
}
],