ASP.Net Core Identity login status lost after deploy

Question

I am using ASP.Net Core and MS Identity, I try to understand why after each deployment the login users are logged out. I am running on a IIS 8.5

I have been trying t

Answer 1

(solution split into a separate answer following Chris comment)

I found a solution to keep the login status, it survives website stop/start, and an update of the website source folder:

public void ConfigureServices(IServiceCollection services)
{
    services.AddDataProtection()
            // This helps surviving a restart: a same app will find back its keys. Just ensure to create the folder.
            .PersistKeysToFileSystem(new DirectoryInfo("\\MyFolder\\keys\\"))
            // This helps surviving a site update: each app has its own store, building the site creates a new app
            .SetApplicationName("MyWebsite")
            .SetDefaultKeyLifetime(TimeSpan.FromDays(90));
}

With these additional lines and the machine key set, the login data stays after site stop/start and IIS server restart, and if the site is rebuilt.

More information there: https://docs.microsoft.com/en-us/aspnet/core/security/data-protection/configuration/overview

More proposed by justserega: https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/?tabs=aspnetcore2x#data-protection

Answer 2

Authentication use Data Protection Stack. If data protection isn't configured, the keys are held in memory and discarded when the app restarts.

If the key ring is stored in memory when the app restarts:

• All cookie-based authentication tokens are invalidated.
• Users are required to sign in again on their next request.
• Any data protected with the key ring can no longer be decrypted. This may include CSRF tokens and ASP.NET Core MVC tempdata cookies.

You have to configure data protection, more information here https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/?tabs=aspnetcore2x#data-protection