@KK1969 Thank you for your interest in Azure App Services. We understand you have some questions on how to design your app service architecture.
- For the basic and higher tiers on app services, you can technically run unlimited apps. This of course has a limit as there is still a finite amount of CPU and memory available. Each app also has supporting services that need to run on the instance. With that being said, I have been working with App Service customers for 7 years and something like an S1 tier app might start having resource limitations around 10 apps. (Please note that there are a lot of variables that come into play regarding apps per instance. As a result, Microsoft does not offer a formal recommendation. Your experiences will be unique to others. The good news is scaling up/down and in/out is easily done within a matter of minutes so you can fine tune your resources as you get a better feel.) At that point, you'd either need to scale out (high rate of traffic) or scale up (demanding apps that are consuming CPU/memory).
- No, an app service plan can be used run either web and/or function apps. This is not an issue.
- Grouping services by app service plan would probably be best done by the number of resources they need. If you have an app that sees traffic peaks for a few hours each day, you might want to setup an auto scale out/in rule. If your other apps do not see much traffic, these might be better off on their own app service plan and that way you do not have to worry about ensuring they can run across multiple instances.
Please let us know if you have further questions or concerns.