ServiceProvider cannot resolve options in configure method

Question

I have asp.net core application. I have Options stored in appsettings.json file. I register the Options with services and then trying to resolve it in Configure method.

However service provider cannot resolve option in Configure method.

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
         services.Configure<HstsOptions>(Configuration.GetSection("HstsOptions"));
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IApplicationLifetime appLifetime,IServiceProvider services)
    { 

            var options = services.GetService<HstsOptions>();
            // service provider cannot resolve options here, it returns null
            app.UseHsts(options);
    }

}

Answer 1

That's because with services.Configure<T>(...) you register not exact T but IOptions<T>. So you have two ways. Either register exact T like

services.AddScoped(provider => provider.GetRequiredService<IOptions<T>>().Value);

or get T through IOptions:

var options = services.GetService<IOptions<HstsOptions>>().Value;

Answer 2

you can change the method signature of Configure and inject anything previously registered into the method like this:

public void Configure(
    IApplicationBuilder app, 
    IHostingEnvironment env, 
    ILoggerFactory loggerFactory, 
    IApplicationLifetime appLifetime,
    IOptions<HstsOptions> hstsOptions)
{ 
        app.UseHsts(hstsOptions.Value);
}

note that when you use services.Configure you are really registering an IOptions of the thing you are registering, and to get the thing you use the .Value property of that