Uniqueness of App Service Instance Id/Name

Question

I have created 3 web applications in ASE V3. All 3 applications are scaled out to a minimum count of 3 to start with. The applications do not share app service plan. They are independent.
My understanding is that 3 applications will spawn on 3 instances with unique name/id. Are these instance names unique across whole azure environment or with in the subscription or what is minimum isolation level in which these instance names/ids are unique?

Answer 1

Hello @Kohli, Naveen

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.

There are two key ways in which infrastructure is isolated with an ASE:

• Firstly, you can leverage Dedicated Hosts which means the underlying hypervisors that your app will run on are only available to you. No more sharing with other customers.
• Secondly, your App Service Environment can be deployed to your own virtual network, ensuring that you have greater control over network security, ingress, and egress for your apps.

Instances in App Service Environment have unique ID of the current VM instance, when the app is scaled out to multiple instances.

VM's id is unique
https://azure.microsoft.com/en-us/blog/accessing-and-using-azure-vm-unique-id/

https://learn.microsoft.com/en-us/azure/app-service/reference-app-settings?tabs=kudu%2Cdotnet#scaling