VM is a Server. VM computing is not serverless computing. To manage servers you need server admins. And that is not software as a software-as-a-service situation. VM in a cloud makes that bad situation a bit worse. For VM in a cloud, you need cloud admin too. And a yearly subscription. In the pre-cloud days that was called a “Virtual Server”.
Later the term “Private” was inserted and “Virtual Private Server” (VPS) was marketed as an “ideal solution”. It was apparently administered by a hosting company and it was much cheaper than a physical server. And it was part of a cluster to make it resilient. And reachable over a WAN in some secure remote location owned and administered by a hosting company.
And all was fine. Until physical server prices dropped through the floor. And until cloud computing appeared.
So what is this “Managed Instance” (MI) we are being sold these days? That is a VM with a driver and mechanic added. You are using it and they are managing it. That is where the price of luxury is coming from.
Serverless computing is made possible by clever infrastructure. In one shift one Microsoft data center is managed by 3 engineers, and that was approximately 30000 VM’s.
MI is cheaper than VPS but not as cheap as serverless. Kubernetes is based on serverless.
VM != ( Cloud == Serverless )
Azure Application Service is an escape hatch from VMs hosting legacy ASP.NET
Azure has a whole layer of abstractions above VM’s. That is an implementational detail. What you experience and enjoy is (as a familiar example) Azure Application Service. An abstraction delivering serverless computing for the customers.
Application Instance is yet another Azure abstraction. Customers upload their web applications into application instances. Yet another layer of decoupling. Thus you do not know and you do not care if your app is on some vm, or on several vm’s , because inbuilt (form of a Load Balancing) enables application instances to multiply (u to 10). To build setup and maintain such a setup nobody is stopping you, but you have been warned: that is a path peppered with shards of glass. Luckily you do not have people to do it.
Thus in that scenario you can abstract away all the cloud machinery and think of your apps in this way:
(Image from: https://markheath.net/post/per-app-scaling-app-service)
Originally published 2022 Dec 2.