Code samples migrated to the new minimal hosting model in ASP.NET Core 6.0

This article provides samples of code migrated to ASP.NET Core 6.0. ASP.NET Core 6.0 uses a new minimal hosting model. For more information, see New hosting model.

Middleware

The following code adds the Static File Middleware to an ASP.NET Core 5 app:

public class Startup
{
    public void Configure(IApplicationBuilder app)
    {
        app.UseStaticFiles();
    }
}

The following code adds the Static File Middleware to an ASP.NET Core 6 app:

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.UseStaticFiles();

app.Run();

WebApplication.CreateBuilder initializes a new instance of the WebApplicationBuilder class with preconfigured defaults. For more information, see ASP.NET Core Middleware

Routing

The following code adds an endpoint to an ASP.NET Core 5 app:

public class Startup
{
    public void Configure(IApplicationBuilder app)
    {
        app.UseRouting();
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapGet("/", () => "Hello World");
        });
    }
}

In .NET 6, routes can be added directly to the WebApplication without an explicit call to UseEndpoints or UseRouting. The following code adds an endpoint to an ASP.NET Core 6 app:

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/", () => "Hello World!");

app.Run();

Note: Routes added directly to the WebApplication execute at the end of the pipeline.

Change the content root, app name, and environment

ASP.NET Core 5

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .UseContentRoot(Directory.GetCurrentDirectory())
        .UseEnvironment(Environments.Staging)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>()
                      .UseSetting(WebHostDefaults.ApplicationKey,
                                  typeof(Program).Assembly.FullName);
        });

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    ApplicationName = typeof(Program).Assembly.FullName,
    ContentRootPath = Directory.GetCurrentDirectory(),
    EnvironmentName = Environments.Staging,
    WebRootPath = "customwwwroot"
});

Console.WriteLine($"Application Name: {builder.Environment.ApplicationName}");
Console.WriteLine($"Environment Name: {builder.Environment.EnvironmentName}");
Console.WriteLine($"ContentRoot Path: {builder.Environment.ContentRootPath}");
Console.WriteLine($"WebRootPath: {builder.Environment.WebRootPath}");

var app = builder.Build();

Change the content root, app name, and environment by environment variables or command line

The following table shows the environment variable and command-line argument used to change the content root, app name, and environment:

feature Environment variable Command-line argument
Application name ASPNETCORE_APPLICATIONNAME --applicationName
Environment name ASPNETCORE_ENVIRONMENT --environment
Content root ASPNETCORE_CONTENTROOT --contentRoot

Add configuration providers

ASP.NET Core 5

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration(config =>
        {
            config.AddIniFile("appsettings.ini");
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(args);

builder.Configuration.AddIniFile("appsettings.ini");

var app = builder.Build();

For detailed information, see File configuration providers in Configuration in ASP.NET Core.

Add logging providers

ASP.NET Core 5

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureLogging(logging =>
        {
            logging.AddJsonConsole();
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(args);

// Configure JSON logging to the console.
builder.Logging.AddJsonConsole();

var app = builder.Build();

For more information, see Logging in .NET Core and ASP.NET Core.

Add services

ASP.NET Core 5

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        // Add the memory cache services
        services.AddMemoryCache();

        // Add a custom scoped service
        services.AddScoped<ITodoRepository, TodoRepository>();
    }
}

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(args);

// Add the memory cache services.
builder.Services.AddMemoryCache();

// Add a custom scoped service.
builder.Services.AddScoped<ITodoRepository, TodoRepository>();
var app = builder.Build();

For more information, see Dependency injection in ASP.NET Core.

Customize IHostBuilder or IWebHostBuilder

Customize IHostBuilder

ASP.NET Core 5

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureHostOptions(o => o.ShutdownTimeout = TimeSpan.FromSeconds(30));
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(args);

// Wait 30 seconds for graceful shutdown.
builder.Host.ConfigureHostOptions(o => o.ShutdownTimeout = TimeSpan.FromSeconds(30));

var app = builder.Build();

Customize IWebHostBuilder

ASP.NET Core 5

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            // Change the HTTP server implementation to be HTTP.sys based.
            webBuilder.UseHttpSys()
                      .UseStartup<Startup>();
        });

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(args);

// Change the HTTP server implementation to be HTTP.sys based.
// Windows only.
builder.WebHost.UseHttpSys();

var app = builder.Build();

Change the web root

By default, the web root is relative to the content root in the wwwroot folder. Web root is where the static files middleware looks for static files. Web root can be changed by setting the WebRootPath property on WebApplicationOptions:

ASP.NET Core 5

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            // Look for static files in webroot.
            webBuilder.UseWebRoot("webroot")
                      .UseStartup<Startup>();
        });

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
    Args = args,
    // Look for static files in webroot
    WebRootPath = "webroot"
});

var app = builder.Build();

Custom dependency injection (DI) container

The following .NET 5 and .NET 6 samples use Autofac

ASP.NET Core 5

Program class

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .UseServiceProviderFactory(new AutofacServiceProviderFactory())
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

Startup

public class Startup
{
    public void ConfigureContainer(ContainerBuilder containerBuilder)
    {
    }
}

ASP.NET Core 6

var builder = WebApplication.CreateBuilder(args);

builder.Host.UseServiceProviderFactory(new AutofacServiceProviderFactory());

// Register services directly with Autofac here. Don't
// call builder.Populate(), that happens in AutofacServiceProviderFactory.
builder.Host.ConfigureContainer<ContainerBuilder>(builder => builder.RegisterModule(new MyApplicationModule()));

var app = builder.Build();

Access additional services

Startup.Configure can inject any service added via the IServiceCollection.

ASP.NET Core 5

public class Startup
{
    // This method gets called by the runtime. Use this method to add services
    // to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IService, Service>();
    }

    // Anything added to the service collection can be injected into Configure.
    public void Configure(IApplicationBuilder app,
                          IWebHostEnvironment env,
                          IHostApplicationLifetime lifetime,
                          IService service,
                          ILogger<Startup> logger)
    {
        lifetime.ApplicationStarted.Register(() =>
            logger.LogInformation($"The application {env.ApplicationName} started" +
                                  $" in the injected {service}"));
    }
}

ASP.NET Core 6

In ASP.NET Core 6:

  • There are a few common services available as top level properties on WebApplication.
  • Additional services need to be manually resolved from the IServiceProvider via WebApplication.Services.
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSingleton<IService, Service>();

var app = builder.Build();

IService service = app.Services.GetRequiredService<IService>();
ILogger logger = app.Logger;
IHostApplicationLifetime lifetime = app.Lifetime;
IWebHostEnvironment env = app.Environment;

lifetime.ApplicationStarted.Register(() =>
    logger.LogInformation(
        $"The application {env.ApplicationName} started" +
        $" with injected {service}"));

Test with WebApplicationFactory or TestServer

ASP.NET Core 5

In the following samples, the test project uses TestServer and WebApplicationFactory<TEntryPoint>. These ship as separate packages that require explicit reference:

WebApplicationFactory

<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="{Version}" />
</ItemGroup>

TestServer

<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="{Version}" />
</ItemGroup>

ASP.NET Core 5 code

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<IHelloService, HelloService>();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IHelloService helloService)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapGet("/", async context =>
            {
                await context.Response.WriteAsync(helloService.HelloMessage);
            });
        });
    }
}

With TestServer

[Fact]
public async Task HelloWorld()
{
    using var host = Host.CreateDefaultBuilder()
        .ConfigureWebHostDefaults(builder =>
        {
            // Use the test server and point to the application's startup
            builder.UseTestServer()
                    .UseStartup<WebApplication1.Startup>();
        })
        .ConfigureServices(services =>
        {
            // Replace the service
            services.AddSingleton<IHelloService, MockHelloService>();
        })
        .Build();

    await host.StartAsync();

    var client = host.GetTestClient();

    var response = await client.GetStringAsync("/");

    Assert.Equal("Test Hello", response);
}

class MockHelloService : IHelloService
{
    public string HelloMessage => "Test Hello";
}

With WebApplicationFactory

[Fact]
public async Task HelloWorld()
{
    var application = new WebApplicationFactory<Program>()
        .WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                services.AddSingleton<IHelloService, MockHelloService>();
            });
        });

    var client = application.CreateClient();

    var response = await client.GetStringAsync("/");

    Assert.Equal("Test Hello", response);
}

class MockHelloService : IHelloService
{
    public string HelloMessage => "Test Hello";
}

ASP.NET Core 6


var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<IHelloService, HelloService>();

var app = builder.Build();

var helloService = app.Services.GetRequiredService<IHelloService>();

app.MapGet("/", async context =>
{
    await context.Response.WriteAsync(helloService.HelloMessage);
});

app.Run();

Project file (.csproj)

The project file can contain one of the following:

<ItemGroup>
    <InternalsVisibleTo Include="MyTestProject" />
</ItemGroup>

Or

[assembly: InternalsVisibleTo("MyTestProject")]

An alternative solution is to make the Program class public. Program can be made public with Top-level statements by defining a public partial Program class in the project or in Program.cs:

var builder = WebApplication.CreateBuilder(args);

// ... Configure services, routes, etc.

app.Run();

public partial class Program { }
[Fact]
public async Task HelloWorld()
{
    var application = new WebApplicationFactory<Program>()
        .WithWebHostBuilder(builder =>
        {
            builder.ConfigureServices(services =>
            {
                services.AddSingleton<IHelloService, MockHelloService>();
            });
        });

    var client = application.CreateClient();

    var response = await client.GetStringAsync("/");

    Assert.Equal("Test Hello", response);
}

class MockHelloService : IHelloService
{
    public string HelloMessage => "Test Hello";
}

The .NET 5 version and .NET 6 version with the WebApplicationFactory by design.