Azure Event Grid で Microsoft Entra アプリケーションを使用して WebHook 配信をセキュリティで保護する

このスクリプトは、Azure Event Grid を使用して Microsoft Entra アプリケーションによって保護された HTTPS エンドポイントにイベントを配信するための構成を提供します。

スクリプトの大まかな手順を次に示します。

1. Microsoft.EventGrid のサービス プリンシパルがない場合は作成します。
2. Webhook 用の Microsoft Entra アプリで、AzureEventGridSecureWebhookSubscriber という名前のロールを作成します。
3. まだ存在しない場合は、イベント サブスクリプション ライター アプリのサービス プリンシパルを作成します。
4. イベント サブスクリプション ライター Microsoft Entra アプリのサービス プリンシパルを AzureEventGridSecureWebhookSubscriber ロールに追加します
5. Microsoft.EventGrid のサービス プリンシパルも AzureEventGridSecureWebhookSubscriber ロールに追加します

サンプル スクリプト - 安定版

# NOTE: Before run this script ensure you are logged in Azure by using "az login" command.

$webhookAppObjectId = "[REPLACE_WITH_YOUR_ID]"
$eventSubscriptionWriterAppId = "[REPLACE_WITH_YOUR_ID]"

# Start execution
try {

    # Creates an application role of given name and description

    Function CreateAppRole([string] $Name, [string] $Description)
    {
        $appRole = New-Object Microsoft.Graph.PowerShell.Models.MicrosoftGraphAppRole
        $appRole.AllowedMemberTypes = New-Object System.Collections.Generic.List[string]
        $appRole.AllowedMemberTypes += "Application";
        $appRole.AllowedMemberTypes += "User";
        $appRole.DisplayName = $Name
        $appRole.Id = New-Guid
        $appRole.IsEnabled = $true
        $appRole.Description = $Description
        $appRole.Value = $Name;

        return $appRole
    }

    # Creates Azure Event Grid Microsoft Entra Application if not exists
    # You don't need to modify this id
    # But Azure Event Grid Entra Application Id is different for different clouds

    $eventGridAppId = "4962773b-9cdb-44cf-a8bf-237846a00ab7" # Azure Public Cloud
    # $eventGridAppId = "54316b56-3481-47f9-8f30-0300f5542a7b" # Azure Government Cloud
    $eventGridSP = Get-MgServicePrincipal -Filter ("appId eq '" + $eventGridAppId + "'")
    if ($eventGridSP.DisplayName -match "Microsoft.EventGrid")
    {
        Write-Host "The Event Grid Microsoft Entra Application is already defined.`n"
    } else {
        Write-Host "Creating the Azure Event Grid Microsoft Entra Application"
        $eventGridSP = New-MgServicePrincipal -AppId $eventGridAppId
    }

    # Creates the Azure app role for the webhook Microsoft Entra application
    $eventGridRoleName = "AzureEventGridSecureWebhookSubscriber" # You don't need to modify this role name
    $app = Get-MgApplication -ObjectId $webhookAppObjectId
    $appRoles = $app.AppRoles

    Write-Host "Microsoft Entra App roles before addition of the new role..."
    Write-Host $appRoles.DisplayName
    
    if ($appRoles.DisplayName -match $eventGridRoleName)
    {
        Write-Host "The Azure Event Grid role is already defined.`n"
    } else {      
        Write-Host "Creating the Azure Event Grid role in Microsoft Entra Application: " $webhookAppObjectId
        $newRole = CreateAppRole -Name $eventGridRoleName -Description "Azure Event Grid Role"
        $appRoles += $newRole
        Update-MgApplication -ApplicationId $webhookAppObjectId -AppRoles $appRoles
    }

    Write-Host "Microsoft Entra App roles after addition of the new role..."
    Write-Host $appRoles.DisplayName

    # Creates the user role assignment for the app that will create event subscription

    $servicePrincipal = Get-MgServicePrincipal -Filter ("appId eq '" + $app.AppId + "'")
    $eventSubscriptionWriterSP = Get-MgServicePrincipal -Filter ("appId eq '" + $eventSubscriptionWriterAppId + "'")

    if ($null -eq $eventSubscriptionWriterSP)
    {
        Write-Host "Create new Microsoft Entra Application"
        $eventSubscriptionWriterSP = New-MgServicePrincipal -AppId $eventSubscriptionWriterAppId
    }

    try
    {
        Write-Host "Creating the Microsoft Entra Application role assignment: " $eventSubscriptionWriterAppId
        $eventGridAppRole = $app.AppRoles | Where-Object -Property "DisplayName" -eq -Value $eventGridRoleName
        New-MgServicePrincipalAppRoleAssignment -ServicePrincipalId $eventSubscriptionWriterSP.Id -PrincipalId $eventSubscriptionWriterSP.Id -ResourceId $servicePrincipal.Id -AppRoleId $eventGridAppRole.Id 
    }
    catch
    {
        if( $_.Exception.Message -like '*Permission being assigned already exists on the object*')
        {
            Write-Host "The Microsoft Entra Application role is already defined.`n"
        }
        else
        {
            Write-Error $_.Exception.Message
        }
        Break
    }

    # Creates the service app role assignment for Event Grid Microsoft Entra Application

    $eventGridAppRole = $app.AppRoles | Where-Object -Property "DisplayName" -eq -Value $eventGridRoleName
    New-MgServicePrincipalAppRoleAssignment -ServicePrincipalId $eventGridSP.Id -PrincipalId $eventGridSP.Id -ResourceId $servicePrincipal.Id -AppRoleId $eventGridAppRole.Id 
    
    # Print output references for backup

    Write-Host ">> Webhook's Microsoft Entra Application Id: $($app.AppId)"
    Write-Host ">> Webhook's Microsoft Entra Application ObjectId Id: $($app.ObjectId)"
}
catch {
  Write-Host ">> Exception:"
  Write-Host $_
  Write-Host ">> StackTrace:"  
  Write-Host $_.ScriptStackTrace
}

スクリプトの説明

詳細については、「Azure Event Grid での Microsoft Entra ID を使用した WebHook 配信のセキュリティ保護」を参照してください。