Configuration of asp.net core using settings - configuration

Question

I'm evaluating asp.net core and .net core and I'm not yet sure about some things. In the past it was possible to configure many components using the web.config out of the box.
To name some examples:
There was the membership-provider and I could implement many providers but I was able ton configure later which provider should be used. This was dependend of the use-case. Now I should use asp.net identity - but I can only find configurations that are performed in sourcecode.
Same for authentication. I can define "CookieAuthentication" and have to set the name, loginpath or the timeout within sourcecode. In the past I was able to set timeout, etc... via web.config.
Is there any way to configure partially these things out of the box from a config-file? Or is this not supported anymore and I have to implement this configuration on my own? In the past this was a really comfortable way.

Answer 1

In ASP.NET Core, Web.config file is used ONLY for IIS configuration, you cannot use it for application configuration, but there are new, better, more flexible configuration options that you can use.
There are multiple configuration sources that you can use, but in this example I'm using json. These examples are from working code in my SimpleAuth project.
You can configure things in startup from configuration files.
First you add a config file in json format that maps to your class. You can see my example class here, and the json file it maps from here
builder.AddJsonFile("simpleauthsettings.json", optional: true);
Then, in the ConfigureServices method you configure your class to be wired up from the config system as shown
services.Configure<SimpleAuthSettings>(Configuration.GetSection("SimpleAuthSettings"));
Then you add an IOptions accessor of your class to the method signature of the Configure method in the Startup.cs
The Dependency Injection will inject it into that method for you so you can use it there to configure things. Specifically I'm setting the cookie authentication scheme and name from my settings object.
The noteworthy part is that you can add whatever you want to the Configure method signature, and as long as it is something that has been registered in the ConfigureServices method, the DI will be able to inject it for you.
public class Startup
{
public Startup(IHostingEnvironment env, IApplicationEnvironment appEnv)
{
var builder = new ConfigurationBuilder()
.AddJsonFile("appsettings.json")
.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);
// this file is the custom configuration file to hydrate my settings from
builder.AddJsonFile("simpleauthsettings.json", optional: true);
....
Configuration = builder.Build();
}
public IConfigurationRoot Configuration { get; set; }
public void ConfigureServices(IServiceCollection services)
{
....
services.Configure<SimpleAuthSettings>(Configuration.GetSection("SimpleAuthSettings"));
....
}
// note that the DI can inject whatever you need into this method signature
// I added IOptions<SimpleAuthSettings> authSettingsAccessor to the method signature
// you can add anything you want as long as you register it in ConfigureServices
public void Configure(
IApplicationBuilder app,
IHostingEnvironment env,
ILoggerFactory loggerFactory,
IOptions<SimpleAuthSettings> authSettingsAccessor
)
{
...
// Add cookie-based authentication to the request pipeline
SimpleAuthSettings authSettings = authSettingsAccessor.Value;
var ApplicationCookie = new CookieAuthenticationOptions
{
AuthenticationScheme = authSettings.AuthenticationScheme,
CookieName = authSettings.AuthenticationScheme,
AutomaticAuthenticate = true,
AutomaticChallenge = true,
LoginPath = new PathString("/Login/Index"),
Events = new CookieAuthenticationEvents
{
//OnValidatePrincipal = SecurityStampValidator.ValidatePrincipalAsync
}
};
app.UseCookieAuthentication(ApplicationCookie);
// authentication MUST be added before MVC
app.UseMvc();
}
}