This change introduces a new service IStartup that can be registere…

…d in the hosting container to override any startup logic. `UseStartup` overloads have been changed to detect `IStartup` and directly put it in the container, or to wrapping it with a `ConventionBasedStartup` implementation to preserve the existing behavior.

- Remove IStartupLoader and add `IStartup` instead that matches the signature hosting cares about
- Moved `UseStartup` to extension methods
- Move existing logic into `ConventionBasedStartup` class

global.json

@@ -1,3 +1,3 @@
 {
  "projects": ["src"]
-}
+}

samples/SampleStartups/StartupBlockingOnStart.cs

@@ -8,16 +8,17 @@
 
 namespace SampleStartups
 {
- public class StartupBlockingOnStart
+ public class StartupBlockingOnStart : StartupBase
  {
- // This method gets called by the runtime. Use this method to add services to the container.
- // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
- public void ConfigureServices(IServiceCollection services)
+ public override IServiceProvider ConfigureServices(IServiceCollection services)
  {
+ // This method gets called by the runtime. Use this method to add services to the container.
+ // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
+ return base.ConfigureServices(services);
  }
 
  // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
- public void Configure(IApplicationBuilder app)
+ public override void Configure(IApplicationBuilder app)
  {
  app.Run(async (context) =>
  {

samples/SampleStartups/StartupConfigureAddresses.cs

@@ -1,22 +1,15 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.DependencyInjection;
 
 // Note that this sample will not run. It is only here to illustrate usage patterns.
 
 namespace SampleStartups
 {
- public class StartupConfigureAddresses
+ public class StartupConfigureAddresses : StartupBase
  {
- // This method gets called by the runtime. Use this method to add services to the container.
- // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
- public void ConfigureServices(IServiceCollection services)
- {
- }
-
  // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
- public void Configure(IApplicationBuilder app)
+ public override void Configure(IApplicationBuilder app)
  {
  app.Run(async (context) =>
  {

samples/SampleStartups/StartupExternallyControlled.cs

@@ -3,25 +3,18 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.DependencyInjection;
 
 // Note that this sample will not run. It is only here to illustrate usage patterns.
 
 namespace SampleStartups
 {
- public class StartupExternallyControlled
+ public class StartupExternallyControlled : StartupBase
  {
  private IWebHost _host;
  private readonly List<string> _urls = new List<string>();
-
- // This method gets called by the runtime. Use this method to add services to the container.
- // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
- public void ConfigureServices(IServiceCollection services)
- {
- }
-
+
  // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
- public void Configure(IApplicationBuilder app)
+ public override void Configure(IApplicationBuilder app)
  {
  app.Run(async (context) =>
  {

samples/SampleStartups/StartupHelloWorld.cs

@@ -1,22 +1,15 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.DependencyInjection;
 
 // Note that this sample will not run. It is only here to illustrate usage patterns.
 
 namespace SampleStartups
 {
- public class StartupHelloWorld
+ public class StartupHelloWorld : StartupBase
  {
- // This method gets called by the runtime. Use this method to add services to the container.
- // For more information on how to configure your application, visit http://go.microsoft.com/fwlink/?LinkID=398940
- public void ConfigureServices(IServiceCollection services)
- {
- }
-
  // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
- public void Configure(IApplicationBuilder app)
+ public override void Configure(IApplicationBuilder app)
  {
  app.Run(async (context) =>
  {

src/Microsoft.AspNetCore.Hosting.Abstractions/IStartup.cs

@@ -0,0 +1,16 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Microsoft.AspNetCore.Hosting
+{
+ public interface IStartup
+ {
+ IServiceProvider ConfigureServices(IServiceCollection services);
+
+ void Configure(IApplicationBuilder app);
+ }
+}

src/Microsoft.AspNetCore.Hosting.Abstractions/IWebHostBuilder.cs

@@ -2,8 +2,6 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 
@@ -26,27 +24,13 @@ public interface IWebHostBuilder
  /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
  IWebHostBuilder UseLoggerFactory(ILoggerFactory loggerFactory);
 
- /// <summary>
- /// Specify the startup type to be used by the web host. 
- /// </summary>
- /// <param name="startupType">The <see cref="Type"/> to be used.</param>
- /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
- IWebHostBuilder UseStartup(Type startupType);
-
  /// <summary>
  /// Specify the delegate that is used to configure the services of the web application.
  /// </summary>
  /// <param name="configureServices">The delegate that configures the <see cref="IServiceCollection"/>.</param>
  /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
  IWebHostBuilder ConfigureServices(Action<IServiceCollection> configureServices);
 
- /// <summary>
- /// Specify the startup method to be used to configure the web application. 
- /// </summary>
- /// <param name="configureApplication">The delegate that configures the <see cref="IApplicationBuilder"/>.</param>
- /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
- IWebHostBuilder Configure(Action<IApplicationBuilder> configureApplication);
-
  /// <summary>
  /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
  /// </summary>

src/Microsoft.AspNetCore.Hosting.Abstractions/WebHostDefaults.cs

@@ -5,7 +5,9 @@ namespace Microsoft.AspNetCore.Hosting
 {
  public static class WebHostDefaults
  {
- public static readonly string ApplicationKey = "application";
+ public static readonly string ApplicationKey = "applicationName";
+ public static readonly string StartupAssemblyKey = "startupAssembly";
+
  public static readonly string DetailedErrorsKey = "detailedErrors";
  public static readonly string EnvironmentKey = "environment";
  public static readonly string ServerKey = "server";

src/Microsoft.AspNetCore.Hosting/Internal/AutoRequestServicesStartupFilter.cs

@@ -3,7 +3,6 @@
 
 using System;
 using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Hosting.Startup;
 
 namespace Microsoft.AspNetCore.Hosting.Internal
 {

src/Microsoft.AspNetCore.Hosting/Startup/ConfigureBuilder.cs → src/Microsoft.AspNetCore.Hosting/Internal/ConfigureBuilder.cs

@@ -6,7 +6,7 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 
-namespace Microsoft.AspNetCore.Hosting.Startup
+namespace Microsoft.AspNetCore.Hosting.Internal
 {
  public class ConfigureBuilder
  {
@@ -51,4 +51,4 @@ private void Invoke(object instance, IApplicationBuilder builder)
  MethodInfo.Invoke(instance, parameters);
  }
  }
-}
+}

src/Microsoft.AspNetCore.Hosting/Startup/ConfigureServicesBuilder.cs → src/Microsoft.AspNetCore.Hosting/Internal/ConfigureServicesBuilder.cs

@@ -6,7 +6,7 @@
 using System.Reflection;
 using Microsoft.Extensions.DependencyInjection;
 
-namespace Microsoft.AspNetCore.Hosting.Startup
+namespace Microsoft.AspNetCore.Hosting.Internal
 {
  public class ConfigureServicesBuilder
  {

src/Microsoft.AspNetCore.Hosting/Internal/ServerLoader.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
 using System.Linq;
 using System.Reflection;
 using Microsoft.AspNetCore.Hosting.Server;

src/Microsoft.AspNetCore.Hosting/Startup/StartupLoader.cs → src/Microsoft.AspNetCore.Hosting/Internal/StartupLoader.cs

@@ -2,45 +2,31 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
 using System.Reflection;
 using Microsoft.Extensions.DependencyInjection;
 
-namespace Microsoft.AspNetCore.Hosting.Startup
+namespace Microsoft.AspNetCore.Hosting.Internal
 {
- public class StartupLoader : IStartupLoader
+ public class StartupLoader
  {
- private readonly IServiceProvider _services;
- private readonly IHostingEnvironment _hostingEnv;
-
- public StartupLoader(IServiceProvider services, IHostingEnvironment hostingEnv)
- {
- _services = services;
- _hostingEnv = hostingEnv;
- }
-
- public StartupMethods LoadMethods(
- Type startupType,
- IList<string> diagnosticMessages)
+ public static StartupMethods LoadMethods(IServiceProvider services, Type startupType, string environmentName)
  {
- var environmentName = _hostingEnv.EnvironmentName;
  var configureMethod = FindConfigureDelegate(startupType, environmentName);
  var servicesMethod = FindConfigureServicesDelegate(startupType, environmentName);
 
  object instance = null;
  if (!configureMethod.MethodInfo.IsStatic || (servicesMethod != null && !servicesMethod.MethodInfo.IsStatic))
  {
- instance = ActivatorUtilities.GetServiceOrCreateInstance(_services, startupType);
+ instance = ActivatorUtilities.GetServiceOrCreateInstance(services, startupType);
  }
 
  return new StartupMethods(configureMethod.Build(instance), servicesMethod?.Build(instance));
  }
 
- public Type FindStartupType(string startupAssemblyName, IList<string> diagnosticMessages)
+ public static Type FindStartupType(string startupAssemblyName, string environmentName)
  {
- var environmentName = _hostingEnv.EnvironmentName;
  if (string.IsNullOrEmpty(startupAssemblyName))
  {
  throw new ArgumentException(

src/Microsoft.AspNetCore.Hosting/Startup/StartupMethods.cs → src/Microsoft.AspNetCore.Hosting/Internal/StartupMethods.cs

@@ -5,7 +5,7 @@
 using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 
-namespace Microsoft.AspNetCore.Hosting.Startup
+namespace Microsoft.AspNetCore.Hosting.Internal
 {
  public class StartupMethods
  {

src/Microsoft.AspNetCore.Hosting/Internal/WebHost.cs

@@ -6,10 +6,10 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Threading;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting.Builder;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Hosting.Server.Features;
-using Microsoft.AspNetCore.Hosting.Startup;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.Extensions.Configuration;
@@ -22,7 +22,9 @@ namespace Microsoft.AspNetCore.Hosting.Internal
  public class WebHost : IWebHost
  {
  private readonly IServiceCollection _applicationServiceCollection;
- private readonly IStartupLoader _startupLoader;
+ private IStartup _startup;
+
+ private readonly IServiceProvider _hostingServiceProvider;
  private readonly ApplicationLifetime _applicationLifetime;
  private readonly WebHostOptions _options;
  private readonly IConfiguration _config;
@@ -34,16 +36,11 @@ public class WebHost : IWebHost
  // Used for testing only
  internal WebHostOptions Options => _options;
 
- // Only one of these should be set
- internal string StartupAssemblyName { get; set; }
- internal StartupMethods Startup { get; set; }
- internal Type StartupType { get; set; }
-
  private IServer Server { get; set; }
 
  public WebHost(
  IServiceCollection appServices,
- IStartupLoader startupLoader,
+ IServiceProvider hostingServiceProvider,
  WebHostOptions options,
  IConfiguration config)
  {
@@ -52,9 +49,9 @@ public WebHost(
  throw new ArgumentNullException(nameof(appServices));
  }
 
- if (startupLoader == null)
+ if (hostingServiceProvider == null)
  {
- throw new ArgumentNullException(nameof(startupLoader));
+ throw new ArgumentNullException(nameof(hostingServiceProvider));
  }
 
  if (config == null)
@@ -65,7 +62,7 @@ public WebHost(
  _config = config;
  _options = options;
  _applicationServiceCollection = appServices;
- _startupLoader = startupLoader;
+ _hostingServiceProvider = hostingServiceProvider;
  _applicationLifetime = new ApplicationLifetime();
  _applicationServiceCollection.AddSingleton<IApplicationLifetime>(_applicationLifetime);
  }
@@ -116,37 +113,18 @@ private void EnsureApplicationServices()
  if (_applicationServices == null)
  {
  EnsureStartup();
- _applicationServices = Startup.ConfigureServicesDelegate(_applicationServiceCollection);
+ _applicationServices = _startup.ConfigureServices(_applicationServiceCollection);
  }
  }
 
  private void EnsureStartup()
  {
- if (Startup != null)
+ if (_startup != null)
  {
  return;
  }
 
- if (StartupType == null)
- {
- var diagnosticTypeMessages = new List<string>();
- StartupType = _startupLoader.FindStartupType(StartupAssemblyName, diagnosticTypeMessages);
- if (StartupType == null)
- {
- throw new ArgumentException(
- diagnosticTypeMessages.Aggregate("Failed to find a startup type for the web application.", (a, b) => a + "\r\n" + b),
- StartupAssemblyName);
- }
- }
-
- var diagnosticMessages = new List<string>();
- Startup = _startupLoader.LoadMethods(StartupType, diagnosticMessages);
- if (Startup == null)
- {
- throw new ArgumentException(
- diagnosticMessages.Aggregate("Failed to find a startup entry point for the web application.", (a, b) => a + "\r\n" + b),
- StartupAssemblyName);
- }
+ _startup = _hostingServiceProvider.GetRequiredService<IStartup>();
  }
 
  private RequestDelegate BuildApplication()
@@ -161,7 +139,7 @@ private RequestDelegate BuildApplication()
  builder.ApplicationServices = _applicationServices;
 
  var startupFilters = _applicationServices.GetService<IEnumerable<IStartupFilter>>();
- var configure = Startup.ConfigureDelegate;
+ Action<IApplicationBuilder> configure = _startup.Configure;
  foreach (var filter in startupFilters.Reverse())
  {
  configure = filter.Configure(configure);