Create-EventGridSubscriptionToAzureFunctionV2.ps1

#
#.SYNOPSIS
#	Creates Event Grid Subscription.

#.DESCRIPTION
#	Creates an Event Grid Subscription (Topic type: Azure Subscription) to a Function App V2

#.OUTPUTS
#	Progress messages
#
Param( 
    [string]$ResourceGroupName,
    [string]$FunctionAppName,
    [string]$FunctionName,
    [string]$EventGridSubscriptionName,
    [string]$FunctionUrl="azurewebsites.net"
    ) 

    Function Get-AppServicePublishingCredentials($resourceGroupName, $functionAppName)
    {   
        $resourceType = "Microsoft.Web/sites/config"
        $resourceName = "$functionAppName/publishingcredentials"
        $publishingCredentials = Invoke-AzureRmResourceAction -ResourceGroupName $resourceGroupName -ResourceType $resourceType -ResourceName $resourceName -Action list -ApiVersion 2015-08-01 -Force
        return $publishingCredentials
    }

    function Get-EncodedCredentials($resourceGroupName, $functionAppName)
    {
        $publishingCredentials = Get-AppServicePublishingCredentials $resourceGroupName $functionAppName
        $pair = "$($publishingCredentials.Properties.PublishingUserName):$($publishingCredentials.Properties.PublishingPassword)"
        $encodedCreds = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes($pair))
        return $encodedCreds  
    }

    function Get-MasterAPIKey($encodedCreds, $functionAppName)
    {
        $result = Invoke-RestMethod -Uri "https://$functionAppName.scm.$FunctionUrl/api/functions/admin/masterkey" -Headers @{Authorization=("Basic {0}" -f $encodedCreds)} 
        return $result.masterKey
    }

    function Get-EventGridExtensionSystemKey($functionAppName, $masterKey)
    {
        $result = Invoke-RestMethod ("https://$functionAppName.$FunctionUrl/admin/host/systemkeys/eventgrid_extension?code=" + $masterKey)
        return $result.value
    }

    function Create-EventGridSubscription($functionAppName, $functionName, $systemKey, $eventGridSubscriptionName)
    {
        $functionEndpointURL = "https://" + $functionAppName + ".$FunctionUrl/runtime/webhooks/eventgrid?functionName=" + $functionName + "&code=" + $systemkey +""

        $subscriptionID=(Get-AzureRmContext).Subscription.Id

        New-AzureRmDeployment `
          -Name egdeployment `
          -Location westeurope `
          -TemplateUri https://raw.githubusercontent.com/Azure/azure-quickstart-templates/master/101-event-grid-resource-events-to-webhook/azuredeploy.json `
          -eventSubName $eventGridSubscriptionName `
          -endpoint $functionEndpointURL
    }
        
# Get the Encoded Publish Credentials, so we can call Kudu API to get master key
$encodedCreds = Get-EncodedCredentials $ResourceGroupName $FunctionAppName
Write-Output "This is the encodedCreds: $encodedCreds"

# Get master key to call Event Grid Extension API
$masterKey = Get-MasterAPIKey $encodedCreds $FunctionAppName
Write-Output "This is the masterKey: $masterkey"

# Get Event Grid SystemKey, so we can create the Event Grid Webhook
$systemKey = Get-EventGridExtensionSystemKey $FunctionAppName $masterkey 
Write-Output "This is the SystemKey: $systemKey"

Write-Output "Creating the Event Grid Subscription:"
Create-EventGridSubscription $FunctionAppName $FunctionName $systemKey $EventGridSubscriptionName