IdentityServer4- Challenge ALL requests to API not just [Authorize] - asp.net-core

Question

I have an ASP.Net Core 2 API using IdentityServer4. I would like challenge ALL requests to the server and invoke the login redirect if the user is not authenticated, calling back to a specific URL after authentication.
The default is to invoke the login redirect only when an unauthenticated user requests a resource protected by the [Authorize] attribute. This will not work in my use case.
Basically, I want the functional equivalent of an [Authorize] attribute for the whole application not just specific controllers.
What is the easiest way to do this? Is there a setting I can use when configuring the services in Startup.cs (services.AddAuthentication)? Or through custom middleware right after app.UseAuthentication()?
I tried the following custom middleware but it says a handler is not configured.
ConfigureServices
services.AddAuthentication(IdentityServerAuthenticationDefaults.AuthenticationScheme)
.AddIdentityServerAuthentication(options =>
{
options.Authority = "https://localhost:4000";
options.ApiName = "myapi";
});
Configure
app.UseAuthentication();
app.Use(async (context, next) =>
{
if (!context.User.Identity.IsAuthenticated)
{
await context.ChallengeAsync(IdentityServerAuthenticationDefaults.AuthenticationScheme, new AuthenticationProperties {RedirectUri= "https://localhost:5000/" });
}
else { await next.Invoke(); }
});
app.UseMvc();

Answer 1

For configuring [Authorize] for the whole controllers, you could try AuthorizeFilter like below
services.AddMvc(config => {
var policy = new AuthorizationPolicyBuilder()
.RequireAuthenticatedUser()
.Build();
config.Filters.Add(new AuthorizeFilter(policy));
})
.SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
For redirecting, you could try configure UserInteraction.LoginUrl
services.AddIdentityServer(opt => {
opt.UserInteraction.LoginUrl = "/Identity/Account/LogIn";
})
.AddDeveloperSigningCredential()
.AddInMemoryPersistedGrants()
.AddInMemoryIdentityResources(Config.GetIdentityResources())
.AddInMemoryApiResources(Config.GetApiResources())
.AddInMemoryClients(Config.GetClients())
.AddAspNetIdentity<IdentityUser>();