Sécuriser la livraison de WebHook avec l’application Microsoft Entra dans Azure Event Grid

Ce script fournit la configuration qui permet de livrer des événements aux points de terminaison HTTPS protégés par l’application Microsoft Entra à l’aide d’Azure Event Grid.

Voici les étapes générales du script :

1. Créer un principal de service pour Microsoft.EventGrid s’il n’en existe pas encore
2. Créer un rôle nommé AzureEventGridSecureWebhookSubscriber dans l’application Microsoft Entra pour votre Webhook.
3. Créer un principal de service pour l’application d’écriture d’abonnement aux événements s’il n’en existe pas encore
4. Ajouter le principal de service de l’application Microsoft Entra d’écriture d’abonnement aux événements au rôle AzureEventGridSecureWebhookSubscriber
5. Ajouter également le principal de service de Microsoft.EventGrid au rôle AzureEventGridSecureWebhookSubscriber

Exemple de script : stable

# 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
}

Explication du script

Pour plus d’informations, consultez Livraison sécurisée de WebHook avec Microsoft Entra ID dans Azure Event Grid.