AspNetCore EF6 Identity Shared Cookie Authentication between apps - authentication

Question

I want to set up multiple webapps in my domain. I am using VS2022 solution with multiple projects and shared class libraries to keep things together.
I would prefer that if I log in into the app, and navigate to any of the others, I would also be logged in into that app automatically, and off course logging out, the same effect.
At the moment, I can log into app 1, go to app 2 and log in there, but when I return to app 1 I am logged out.
Currently in my startup I have the following
services.ConfigureApplicationCookie(options =>
{
options.Cookie.Name = "AspNet.SharedCookie";
options.Cookie.Path = "/";
options.Cookie.Domain = "localhost"; // "*.example.com";
options.Cookie.SameSite = SameSiteMode.Lax;
});
services.AddAuthentication("AspNet.SharedCookie");
Identity platform is Microsoft.Identity from sql server. I dont think there is any issue there as I am succesfully loggin in/out everywhere.
services.AddDefaultIdentity<ApplicationUser>(options => options.SignIn.RequireConfirmedAccount = false)
.AddRoles<IdentityRole>().AddEntityFrameworkStores<ApplicationDbContext>();
My apps running currently localhost:1000, localhost:2000, localhost:3000 etc but this would eventually become app1.example.com, app2.example.com etc.
The AspNet.SharedCookie is available on all sites, but obviously changes based on the current app.
I even though changing the app Id but I dont think thats a good idea, besides, had no effect.
<PropertyGroup>
<TargetFramework>net6.0</TargetFramework>
<Nullable>enable</Nullable>
<ImplicitUsings>enable</ImplicitUsings>
<UserSecretsId>aspnet-DEV.app1-USE THIS SAME ID IN ALL APPS</UserSecretsId>
</PropertyGroup>
How do I get this right to keep all apps standard with there own log in identity, but switching apps should keep that login info?

Answer 1

Thanks for your sharing, and I solve the issue by adding the code below.
services.AddDataProtection().PersistKeysToFileSystem(new DirectoryInfo(#"c:\temp-keys")).SetApplicationName("testapp");
Test Result:
My Code