ASP.NET Core 2.0 Preview 1: How to set up Cookie Authentication with custom login path

Question

In ASP.NET Core 2.0 the .UseAuthentication() middleware has a breaking change that no longer allows the old syntax mentioned here to work.

The new version appears to

Answer 1

Updated as this has changed slightly again in the 2.0 RTM bits

It turns out it's a lot easier than expected, but as the official documentation hasn't been updated yet, here is exactly what works for plain Cookie auth:

Configuration:

In ConfigureServices() configure the specific Authentication mechanism:

services
    .AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
    .AddCookie(o =>
    {
        o.LoginPath = "/api/login";
        o.LogoutPath = "/api/logout";
        // additional config options here
    });

Then in Configure() to actually hook up the middleware:

app.UseAuthentication();

Using the Auth Components

Then to use the actual Auth components the logic has shifted from the HttpContext.Authentication object, down to just HttpContext in application logic like controller code:

await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme,
            new ClaimsPrincipal(identity));

or:

await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);