Add overloads to ConfigureServices to accept the WebHostBuilderContext and make the context accessible in more locations.

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

@@ -13,6 +13,15 @@ namespace Microsoft.AspNetCore.Hosting
     /// </summary>
     public interface IWebHostBuilder
     {
+        /// <summary>
+        /// The <see cref="WebHostBuilderContext"/> used during building.
+        /// </summary>
+        /// <remarks>
+        /// Some properties of this type will be null whilst it is being built, most noteably the <see cref="ILoggerFactory"/> will
+        /// be null inside the <see cref="ConfigureAppConfiguration(Action{WebHostBuilderContext, IConfigurationBuilder})"/> method.
+        /// </remarks>
+        WebHostBuilderContext Context { get; }
+
         /// <summary>
         /// Builds an <see cref="IWebHost"/> which hosts a web application.
         /// </summary>
@@ -32,6 +41,13 @@ namespace Microsoft.AspNetCore.Hosting
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
         IWebHostBuilder ConfigureServices(Action<IServiceCollection> configureServices);
 
+        /// <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<WebHostBuilderContext, IServiceCollection> configureServices);
+
         /// <summary>
         /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
         /// </summary>
@@ -44,7 +60,7 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="configureLogging">The delegate that configures the <see cref="ILoggerFactory"/>.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder ConfigureLogging<T>(Action<T> configureLogging) where T : ILoggerFactory;
+        IWebHostBuilder ConfigureLogging<T>(Action<WebHostBuilderContext, T> configureLogging) where T : ILoggerFactory;
 
         /// <summary>
         /// Add or replace a setting in the configuration.
@@ -75,6 +91,6 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="configureDelegate">The delegate for configuring the <see cref="IConfigurationBuilder" /> that will be used to construct an <see cref="IConfiguration" />.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder ConfigureConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate);
+        IWebHostBuilder ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate);
     }
 }

src/Microsoft.AspNetCore.Hosting.Abstractions/exceptions.net45.json

@@ -2,7 +2,7 @@
   {
     "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureLogging<T0>(System.Action<T0> configureLogging) where T0 : Microsoft.Extensions.Logging.ILoggerFactory",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureLogging<T0>(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, T0> configureLogging) where T0 : Microsoft.Extensions.Logging.ILoggerFactory",
     "Kind": "Addition"
   },
   {
@@ -35,5 +35,17 @@
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHost : System.IDisposable",
     "NewMemberId": "System.Threading.Tasks.Task StopAsync(System.Threading.CancellationToken cancellationToken)",
     "Kind": "Addition"
+  },
+  {
+    "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.WebHostBuilderContext get_Context()",
+    "Kind": "Addition"
+  },
+  {
+    "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureServices(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, Microsoft.Extensions.DependencyInjection.IServiceCollection> configureServices)",
+    "Kind": "Addition"
   }
 ]

src/Microsoft.AspNetCore.Hosting.Abstractions/exceptions.netcore.json

@@ -2,7 +2,7 @@
   {
     "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureLogging<T0>(System.Action<T0> configureLogging) where T0 : Microsoft.Extensions.Logging.ILoggerFactory",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureLogging<T0>(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, T0> configureLogging) where T0 : Microsoft.Extensions.Logging.ILoggerFactory",
     "Kind": "Addition"
   },
   {
@@ -14,7 +14,7 @@
   {
     "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
-    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureConfiguration(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, Microsoft.Extensions.Configuration.IConfigurationBuilder> configureDelegate)",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureAppConfiguration(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, Microsoft.Extensions.Configuration.IConfigurationBuilder> configureDelegate)",
     "Kind": "Addition"
   },
   {
@@ -35,5 +35,17 @@
     "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHost : System.IDisposable",
     "NewMemberId": "System.Threading.Tasks.Task StopAsync(System.Threading.CancellationToken cancellationToken)",
     "Kind": "Addition"
+  },
+  {
+    "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.WebHostBuilderContext get_Context()",
+    "Kind": "Addition"
+  },
+  {
+    "OldTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewTypeId": "public interface Microsoft.AspNetCore.Hosting.IWebHostBuilder",
+    "NewMemberId": "Microsoft.AspNetCore.Hosting.IWebHostBuilder ConfigureServices(System.Action<Microsoft.AspNetCore.Hosting.WebHostBuilderContext, Microsoft.Extensions.DependencyInjection.IServiceCollection> configureServices)",
+    "Kind": "Addition"
   }
 ]

src/Microsoft.AspNetCore.Hosting/WebHostBuilder.cs

@@ -25,14 +25,17 @@ namespace Microsoft.AspNetCore.Hosting
     public class WebHostBuilder : IWebHostBuilder
     {
         private readonly IHostingEnvironment _hostingEnvironment;
-        private readonly List<Action<IServiceCollection>> _configureServicesDelegates;
+        private readonly List<Action<WebHostBuilderContext, IServiceCollection>> _configureServicesDelegates;
-        private readonly List<Action<ILoggerFactory>> _configureLoggingDelegates;
+        private readonly List<Action<WebHostBuilderContext, ILoggerFactory>> _configureLoggingDelegates;
 
         private IConfiguration _config;
         private WebHostOptions _options;
         private bool _webHostBuilt;
         private Func<WebHostBuilderContext, ILoggerFactory> _createLoggerFactoryDelegate;
         private List<Action<WebHostBuilderContext, IConfigurationBuilder>> _configureConfigurationBuilderDelegates;
+        private WebHostBuilderContext _hostingContext;
+
+        public WebHostBuilderContext Context { get { return _hostingContext; } }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="WebHostBuilder"/> class.
@@ -40,8 +43,8 @@ namespace Microsoft.AspNetCore.Hosting
         public WebHostBuilder()
         {
             _hostingEnvironment = new HostingEnvironment();
-            _configureServicesDelegates = new List<Action<IServiceCollection>>();
+            _configureServicesDelegates = new List<Action<WebHostBuilderContext, IServiceCollection>>();
-            _configureLoggingDelegates = new List<Action<ILoggerFactory>>();
+            _configureLoggingDelegates = new List<Action<WebHostBuilderContext, ILoggerFactory>>();
             _configureConfigurationBuilderDelegates = new List<Action<WebHostBuilderContext, IConfigurationBuilder>>();
 
             _config = new ConfigurationBuilder()
@@ -113,6 +116,23 @@ namespace Microsoft.AspNetCore.Hosting
                 throw new ArgumentNullException(nameof(configureServices));
             }
 
+            _configureServicesDelegates.Add((_, collection) => configureServices(collection));
+            return this;
+        }
+
+        /// <summary>
+        /// Adds a delegate for configuring additional services for the host or web application. This may be called
+        /// multiple times.
+        /// </summary>
+        /// <param name="configureServices">A delegate for configuring the <see cref="IServiceCollection"/>.</param>
+        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        public IWebHostBuilder ConfigureServices(Action<WebHostBuilderContext, IServiceCollection> configureServices)
+        {
+            if (configureServices == null)
+            {
+                throw new ArgumentNullException(nameof(configureServices));
+            }
+
             _configureServicesDelegates.Add(configureServices);
             return this;
         }
@@ -129,7 +149,7 @@ namespace Microsoft.AspNetCore.Hosting
                 throw new ArgumentNullException(nameof(configureLogging));
             }
 
-            _configureLoggingDelegates.Add(configureLogging);
+            _configureLoggingDelegates.Add((_, factory) => configureLogging(factory));
             return this;
         }
 
@@ -155,17 +175,17 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="configureLogging">The delegate that configures the <see cref="ILoggerFactory"/>.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        public IWebHostBuilder ConfigureLogging<T>(Action<T> configureLogging) where T : ILoggerFactory
+        public IWebHostBuilder ConfigureLogging<T>(Action<WebHostBuilderContext, T> configureLogging) where T : ILoggerFactory
         {
             if (configureLogging == null)
             {
                 throw new ArgumentNullException(nameof(configureLogging));
             }
-            _configureLoggingDelegates.Add(factory =>
+            _configureLoggingDelegates.Add((context, factory) =>
             {
                 if (factory is T typedFactory)
                 {
-                    configureLogging(typedFactory);
+                    configureLogging(context, typedFactory);
                 }
             });
             return this;
@@ -176,7 +196,7 @@ namespace Microsoft.AspNetCore.Hosting
         /// </summary>
         /// <param name="configureDelegate">The delegate for configuring the <see cref="IConfigurationBuilder" /> that will be used to construct an <see cref="IConfiguration" />.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        public IWebHostBuilder ConfigureConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate)
+        public IWebHostBuilder ConfigureAppConfiguration(Action<WebHostBuilderContext, IConfigurationBuilder> configureDelegate)
         {
             if (configureDelegate == null)
             {
@@ -241,14 +261,15 @@ namespace Microsoft.AspNetCore.Hosting
             var appEnvironment = PlatformServices.Default.Application;
             var contentRootPath = ResolveContentRootPath(_options.ContentRootPath, appEnvironment.ApplicationBasePath);
             var applicationName = _options.ApplicationName ?? appEnvironment.ApplicationName;
-            var hostingContext = new WebHostBuilderContext
+
+            _hostingContext = new WebHostBuilderContext
             {
                 Configuration = _config
             };
 
             // Initialize the hosting environment
             _hostingEnvironment.Initialize(applicationName, contentRootPath, _options);
-            hostingContext.HostingEnvironment = _hostingEnvironment;
+            _hostingContext.HostingEnvironment = _hostingEnvironment;
 
             var services = new ServiceCollection();
             services.AddSingleton(_hostingEnvironment);
@@ -259,17 +280,17 @@ namespace Microsoft.AspNetCore.Hosting
 
             foreach (var configureConfiguration in _configureConfigurationBuilderDelegates)
             {
-                configureConfiguration(hostingContext, builder);
+                configureConfiguration(_hostingContext, builder);
             }
 
             var configuration = builder.Build();
             services.AddSingleton<IConfiguration>(configuration);
-            hostingContext.Configuration = configuration;
+            _hostingContext.Configuration = configuration;
 
             // The configured ILoggerFactory is added as a singleton here. AddLogging below will not add an additional one.
-            var loggerFactory = _createLoggerFactoryDelegate?.Invoke(hostingContext) ?? new LoggerFactory(configuration.GetSection("Logging"));
+            var loggerFactory = _createLoggerFactoryDelegate?.Invoke(_hostingContext) ?? new LoggerFactory(configuration.GetSection("Logging"));
             services.AddSingleton(loggerFactory);
-            hostingContext.LoggerFactory = loggerFactory;
+            _hostingContext.LoggerFactory = loggerFactory;
 
             var exceptions = new List<Exception>();
 
@@ -307,7 +328,7 @@ namespace Microsoft.AspNetCore.Hosting
             // Kept for back-compat, will remove once ConfigureLogging is removed.
             foreach (var configureLogging in _configureLoggingDelegates)
             {
-                configureLogging(loggerFactory);
+                configureLogging(_hostingContext, loggerFactory);
             }
 
             //This is required to add ILogger of T.
@@ -362,7 +383,7 @@ namespace Microsoft.AspNetCore.Hosting
 
             foreach (var configureServices in _configureServicesDelegates)
             {
-                configureServices(services);
+                configureServices(_hostingContext, services);
             }
 
             return services;

src/Microsoft.AspNetCore.Hosting/WebHostBuilderExtensions.cs

@@ -95,26 +95,28 @@ namespace Microsoft.AspNetCore.Hosting
         }
 
         /// <summary>
-        /// Configures and use a <see cref="LoggerFactory"/> for the web host.
+        /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
         /// </summary>
-        /// <param name="hostBuilder">The <see cref="IWebHostBuilder"/> to configure.</param>
+        /// <param name="hostBuilder">The <see cref="IWebHostBuilder" /> to configure.</param>
-        /// <param name="configure">A callback used to configure the <see cref="LoggerFactory"/> that will be added as a singleton and used by the application.</param>
+        /// <param name="configureLogging">The delegate that configures the <see cref="ILoggerFactory"/>.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        public static IWebHostBuilder UseLoggerFactory(this IWebHostBuilder hostBuilder, Action<WebHostBuilderContext, LoggerFactory> configure)
+        public static IWebHostBuilder ConfigureLogging(this IWebHostBuilder hostBuilder, Action<WebHostBuilderContext, LoggerFactory> configureLogging)
         {
-            if (configure == null)
+            hostBuilder.ConfigureLogging(configureLogging);
-            {
-                throw new ArgumentNullException(nameof(configure));
-            }
-
-            hostBuilder.UseLoggerFactory(context =>
-            {
-                var loggerFactory = new LoggerFactory();
-                configure(context, loggerFactory);
-                return loggerFactory;
-            });
-
             return hostBuilder;
         }
+
+        /// <summary>
+        /// Adds a delegate for configuring the provided <see cref="ILoggerFactory"/>. This may be called multiple times.
+        /// </summary>
+        /// <param name="hostBuilder">The <see cref="IWebHostBuilder" /> to configure.</param>
+        /// <param name="configureLogging">The delegate that configures the <see cref="ILoggerFactory"/>.</param>
+        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        public static IWebHostBuilder ConfigureLogging<T>(this IWebHostBuilder hostBuilder, Action<T> configureLogging) where T : ILoggerFactory
+        {
+            hostBuilder.ConfigureLogging<T>((_, factory) => configureLogging(factory));
+            return hostBuilder;
+        }
+
     }
 }

test/Microsoft.AspNetCore.Hosting.Tests/WebHostBuilderTests.cs

@@ -257,6 +257,29 @@ namespace Microsoft.AspNetCore.Hosting
             Assert.Same(loggerFactory, host.Services.GetService<ILoggerFactory>());
         }
 
+        [Fact]
+        public void HostingContextCanBeUsed()
+        {
+            var hostBuilder = new WebHostBuilder()
+                 .ConfigureAppConfiguration((context, configBuilder) => configBuilder
+                    .AddInMemoryCollection(
+                            new KeyValuePair<string, string>[]
+                            {
+                                new KeyValuePair<string, string>("key1", "value1")
+                            }))
+                 .ConfigureLogging((context, factory) =>
+                 {
+                     Assert.Equal("value1", context.Configuration["key1"]);
+                 })
+                 .UseServer(new TestServer())
+                 .UseStartup<StartupNoServices>();
+
+            hostBuilder.Build();
+
+            //Verify property on builder is set.
+            Assert.Equal("value1", hostBuilder.Context.Configuration["key1"]);
+        }
+
         [Fact]
         public void ConfigureLoggingCalledIfLoggerFactoryTypeMatches()
         {
@@ -322,7 +345,7 @@ namespace Microsoft.AspNetCore.Hosting
         {
             var hostBuilder = new WebHostBuilder()
                 .UseSetting("key1", "value1")
-                .ConfigureConfiguration((context, configBuilder) =>
+                .ConfigureAppConfiguration((context, configBuilder) =>
                 {
                     var config = configBuilder.Build();
                     Assert.Equal("value1", config["key1"]);
@@ -336,7 +359,7 @@ namespace Microsoft.AspNetCore.Hosting
         public void CanConfigureConfigurationAndRetrieveFromDI()
         {
             var hostBuilder = new WebHostBuilder()
-                .ConfigureConfiguration((_, configBuilder) =>
+                .ConfigureAppConfiguration((_, configBuilder) =>
                 {
                     configBuilder
                         .AddInMemoryCollection(