How do you configure Azure App Service Environment for an ASP.NET Core API?

Isolating Your Backend in Azure

Running a public-facing ASP.NET Core API on shared infrastructure invites unnecessary risk. A dedicated App Service Environment (ASE) gives you isolated compute and networking inside Azure's backbone, which is exactly what compliance-heavy workloads need.

Prerequisites and Deployment

You will need an existing Azure subscription, an active App Service plan, and the Azure CLI or portal access. The ASE itself is a separate resource group that must be provisioned before you attach any app to it.

// Create the ASE resource group and environment using the Azure CLI.
// This command provisions the isolated virtual network and dedicated App Service plan.
var ase = await Azure.Resources.CreateAppServiceEnvironmentAsync(
    resourceGroupName: "ase-rg",
    name: "my-ase",
    location: "East US",
    sku: new AppServiceEnvironmentSku(SkuName.StandardS1, SkuTier.Standard),
    subnetResourceId: "/subscriptions/.../subnets/ase-subnet");

// Configure the web app to run inside the ASE by linking its App Service Plan.
var webApp = await Azure.WebApps.Define(webAppName: "api-ase")
    .WithRegion(Region.USEast)
    .WithExistingResourceGroup("ase-rg")
    .WithAppServicePlan(planName: "ase-plan")
    .CreateAsync();

After deployment, verify connectivity by curling the app's private endpoint from a VM inside the same subnet. If the request fails, check the network rules and the ASE's outbound IP restrictions.