Here’s the process to create a new app:
- User makes a request to create a new site.
- ARM makes sure user has access to the resource to allow the given operation (create in this case) and forwards the requests to App Service Geo-Master.
- Geo-Master finds the best suitable scale unit for the user’s request and forwards the request.
- The scale unit creates the new application.
- Geo-Master reports success on the create request.
While it’s important to understand that App Service has many scale units, your application usually runs within a single App Service scale unit. Even when using Azure Traffic Manager to run in multiple regions, your application runs in two or more separate scale units. However, from the individual scale unit point of view, your app is constrained to a single scale unit.
Excerpt from MSDN - February 2017 Article