azureazure-web-app-servicearrsticky-session

Is in proc session state replicated amongst Azure instances in an app service plan?

I'm a bit nervous about disabling ARR Affinity for my app service because I don't fully understand the following:

  1. Where is the session state stored?
  2. If it's stored InProc (on the VM), is that shared amongst the other instances in my app service?

I'm using a .NET 4.6.2 API, I can't see any reference to SessionStateProvider, so can I assume session state is stored in process?

Solution

  • InProc mode is used for session state storage by default. It is not replicated or shared between instances of an app service because each instance has its own application process and set of objects in memory.

    If your application relies on session state and you want to disable ARR Affinity, then you should look at using out-of-proc session storage, for example SQL Server or Redis.