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Introduction to App Service Environment v2

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Important

This article is about App Service Environment v2, which is used with Isolated App Service plans. App Service Environment v1 and v2 are retired as of 31 August 2024. There's a new version of App Service Environment that is easier to use and runs on more powerful infrastructure. To learn more about the new version, start with the Introduction to the App Service Environment. If you're currently using App Service Environment v1, please follow the steps in this article to migrate to the new version.

As of 31 August 2024, Service Level Agreement (SLA) and Service Credits no longer apply for App Service Environment v1 and v2 workloads that continue to be in production since they are retired products. Decommissioning of the App Service Environment v1 and v2 hardware has begun, and this may affect the availability and performance of your apps and data.

You must complete migration to App Service Environment v3 immediately or your apps and resources may be deleted. We will attempt to auto-migrate any remaining App Service Environment v1 and v2 on a best-effort basis using the in-place migration feature, but Microsoft makes no claim or guarantees about application availability after auto-migration. You may need to perform manual configuration to complete the migration and to optimize your App Service plan SKU choice to meet your needs. If auto-migration isn't feasible, your resources and associated app data will be deleted. We strongly urge you to act now to avoid either of these extreme scenarios.

If you need additional time, we can offer a one-time 30-day grace period for you to complete your migration. For more information and to request this grace period, review the grace period overview, and then go to Azure portal and visit the Migration blade for each of your App Service Environments.

For the most up-to-date information on the App Service Environment v1/v2 retirement, see the App Service Environment v1 and v2 retirement update.

Overview

The Azure App Service Environment v2 is an Azure App Service feature that provides a fully isolated and dedicated environment for securely running App Service apps at high scale. This capability can host your:

  • Windows web apps
  • Linux web apps
  • Docker containers
  • Functions

Note

Linux web apps and docker containers are not supported in Azure Government and Microsoft Azure operated by 21Vianet regions.

App Service environments (ASEs) are appropriate for application workloads that require:

  • Very high scale.
  • Isolation and secure network access.
  • High memory utilization.

Customers can create multiple ASEs within a single Azure region or across multiple Azure regions. This flexibility makes ASEs ideal for horizontally scaling stateless application tiers in support of high requests per second (RPS) workloads.

ASEs host applications from only one customer and do so in one of their VNets. Customers have fine-grained control over inbound and outbound application network traffic. Applications can establish high-speed secure connections over VPNs to on-premises corporate resources.

Dedicated environment

An ASE is dedicated environment that is exclusive to a single customer and can host 200 App Service plan total instances. A single Isolated SKU App Service plan can have up to 100 instances in it. When you add up all the instances from all of the App Service plans in that ASE, the total must be less than or equal to 200.

An ASE is composed of front ends and workers. Front ends are responsible for HTTP/HTTPS termination and automatic load balancing of app requests within an ASE. Front ends are automatically added as the App Service plans in the ASE are scaled out.

Workers are roles that host customer apps. Workers are available in three fixed sizes:

  • One vCPU/3.5 GB RAM
  • Two vCPU/7 GB RAM
  • Four vCPU/14 GB RAM

Customers do not need to manage front ends and workers. All infrastructure is automatically added as customers scale out their App Service plans. As App Service plans are created or scaled in an ASE, the required infrastructure is added or removed as appropriate.

There is a flat monthly rate for an ASE that pays for the infrastructure and doesn't change with the size of the ASE. In addition, there is a cost per App Service plan vCPU. All apps hosted in an ASE are in the Isolated pricing SKU. For information on pricing for an ASE, see the App Service pricing page and review the available options for ASEs.

Virtual network support

The ASE feature is a deployment of the Azure App Service directly into a customer's Azure Resource Manager virtual network. To learn more about Azure virtual networks, see the Azure virtual networks FAQ. An ASE always exists in a virtual network, and more precisely, within a subnet of a virtual network. You can use the security features of virtual networks to control inbound and outbound network communications for your apps.

An ASE can be either internet-facing with a public IP address or internal-facing with only an Azure internal load balancer (ILB) address.

Network Security Groups restrict inbound network communications to the subnet where an ASE resides. You can use NSGs to run apps behind upstream devices and services such as WAFs and network SaaS providers.

Apps also frequently need to access corporate resources such as internal databases and web services. If you deploy the ASE in a virtual network that has a VPN connection to the on-premises network, the apps in the ASE can access the on-premises resources. This capability is true regardless of whether the VPN is a site-to-site or Azure ExpressRoute VPN.

For more information on how ASEs work with virtual networks and on-premises networks, see App Service Environment network considerations.

App Service Environment v1

App Service Environment has three versions: ASEv1, ASEv2, and ASEv3. The preceding information was based on ASEv2. This section shows you the differences between ASEv1 and ASEv2. To learn more about, see App Service Environment v3 introduction

In ASEv1, you need to manage all of the resources manually. That includes the front ends, workers, and IP addresses used for IP-based TLS/SSL bindings. Before you can scale out your App Service plan, you need to first scale out the worker pool where you want to host it.

ASEv1 uses a different pricing model from ASEv2. In ASEv1, you pay for each vCPU allocated. That includes vCPUs used for front ends or workers that aren't hosting any workloads. In ASEv1, the default maximum-scale size of an ASE is 55 total hosts. That includes workers and front ends. One advantage to ASEv1 is that it can be deployed in a classic virtual network and a Resource Manager virtual network. To learn more about ASEv1, see App Service Environment v1 introduction.