What is different azure function app and app service plan?

Question

What is different azure function app and app service plan ?

I think;

• Function app is a core layer - where hosted code and execute

• App service plan is higher layer of function app - it can be covering function app. For example, it can cover network layer for function app.

But I see in function app has Vnet integration feature and app service plan has virtual network integration too. I am confused with it.

What is different azure function app and app service plan in network part ?

p/s: I have created virtual network and assign app service plan to that VNET. then I deployed a function app into app service, but this function does not stay in that VNET. how to verify that ?

Answer 1

An App Service Plan is the environment which you pay for.

You can then run different workloads including function apps within the App Service Plan. Grouping workloads in a single App Service Plan can save you money compared with having different App Service Plans for each App Function.

The VNET configuration is both at the App Service Plan and the App Service / Function App level. You do not necessarily want all App Services / Function Apps in the same App Service Plan to run on the same VNET.

Answer 2

There are a few things that will help you to understand this little better and you can also verify through Azure Portal. After all, it's all the hosting plan you want to use.

1. App Service Plan: This is something a root consumption plan you are paying for. kind of resources you want for much of your work. (I would say - choose this wisely)

2. Function App: This resource has 3-4 different kinds of hosting plan options (i) Consumption plan (ii) Premium Plan (iii) App Service Plan (iV) ASE. now, if you have notice - App Service Plan (item iii) is also one of the options. Not necessary that is only an option. So, in other words; Function App can sit outside the App Service plan (like Consumption plan) where it will deploy separately.

At this moment Question might come - what could be a difference. for that visit Microsoft's well-documented link here which states you are paying and resources are getting allocated during the function real-use whereas, App Service Plan uses your own app Dedicated service plan which you already have decided a lot earlier in the cycle.

Your last question - How do we confirm? well, Open App Service Plan inside Azure Portal and there is an essential section where you will find App(s)/ Slot(s). Click on that you will see how many app services/ function apps already sharing that specific App Service Plan like below: