Ordering sensitive configuration #582

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

@@ -2,10 +2,8 @@
 // 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 Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting.Server;
-using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
 namespace Microsoft.AspNetCore.Hosting
@@ -19,20 +17,6 @@ namespace Microsoft.AspNetCore.Hosting
         /// Builds an <see cref="IWebHost"/> which hosts a web application.
         /// </summary>
         IWebHost Build();
-        
-        /// <summary>
-        /// Gets the raw settings to be used by the web host. Values specified here will override 
-        /// the configuration set by <see cref="UseConfiguration(IConfiguration)"/>.
-        /// </summary>
-        IDictionary<string, string> Settings { get; }
-
-        /// <summary>
-        /// Specify the <see cref="IConfiguration"/> to be used by the web host. If no configuration is
-        /// provided to the builder, the default configuration will be used. 
-        /// </summary>
-        /// <param name="configuration">The <see cref="IConfiguration"/> to be used.</param>
-        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
-        IWebHostBuilder UseConfiguration(IConfiguration configuration);
 
         /// <summary>
         /// Specify the <see cref="IServerFactory"/> to be used by the web host.
@@ -63,11 +47,18 @@ namespace Microsoft.AspNetCore.Hosting
         IWebHostBuilder Configure(Action<IApplicationBuilder> configureApplication);
 
         /// <summary>
-        /// Add or replace a setting in <see cref="Settings"/>.
+        /// Add or replace a setting in the configuration.
         /// </summary>
         /// <param name="key">The key of the setting to add or replace.</param>
         /// <param name="value">The value of the setting to add or replace.</param>
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
         IWebHostBuilder UseSetting(string key, string value);
+
+        /// <summary>
+        /// Get the setting value from the configuration.
+        /// </summary>
+        /// <param name="key">The key of the setting to look up.</param>
+        /// <returns>The value the setting currently contains.</returns>
+        string GetSetting(string key);
     }
 }

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

@@ -0,0 +1,34 @@
+// 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.Collections.Generic;
+using Microsoft.Extensions.Configuration;
+
+namespace Microsoft.AspNetCore.Hosting.Internal
+{
+    public static class IConfigurationExtensions
+    {
+        // Temporary until Configuration/issues/370 is implemented.
+        public static IEnumerable<KeyValuePair<string, string>> GetFlattenedSettings(this IConfiguration configuration)
+        {
+            var stack = new Stack<IConfiguration>();
+            stack.Push(configuration);
+
+            while (stack.Count > 0)
+            {
+                var config = stack.Pop();
+                var section = config as IConfigurationSection;
+
+                if (section != null)
+                {
+                    yield return new KeyValuePair<string, string>(section.Path, section.Value);
+                }
+
+                foreach (var child in config.GetChildren())
+                {
+                    stack.Push(child);
+                }
+            }
+        }
+    }
+}

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

@@ -4,7 +4,7 @@
 using System.Collections.Generic;
 using Microsoft.Extensions.Configuration;
 
-namespace Microsoft.AspNetCore.Hosting
+namespace Microsoft.AspNetCore.Hosting.Internal
 {
     public class WebHostConfiguration
     {

src/Microsoft.AspNetCore.Hosting/WebHostBuilder.cs

@@ -2,7 +2,6 @@
 // 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.Diagnostics;
 using System.Runtime.Versioning;
 using Microsoft.AspNetCore.Builder;
@@ -28,7 +27,7 @@ namespace Microsoft.AspNetCore.Hosting
         private readonly IHostingEnvironment _hostingEnvironment;
         private readonly ILoggerFactory _loggerFactory;
 
-        private IConfiguration _config;
+        private IConfiguration _config = new ConfigurationBuilder().AddInMemoryCollection().Build();
         private WebHostOptions _options;
 
         private Action<IServiceCollection> _configureServices;
@@ -40,26 +39,12 @@ namespace Microsoft.AspNetCore.Hosting
         // Only one of these should be set
         private IServerFactory _serverFactory;
 
-        private IDictionary<string, string> _settings = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-
         public WebHostBuilder()
         {
             _hostingEnvironment = new HostingEnvironment();
             _loggerFactory = new LoggerFactory();
         }
 
-        /// <summary>
-        /// Gets the raw settings to be used by the web host. Values specified here will override 
-        /// the configuration set by <see cref="UseConfiguration(IConfiguration)"/>.
-        /// </summary>
-        public IDictionary<string, string> Settings
-        {
-            get
-            {
-                return _settings;
-            }
-        }
-
         /// <summary>
         /// Add or replace a setting in <see cref="Settings"/>.
         /// </summary>
@@ -68,20 +53,18 @@ namespace Microsoft.AspNetCore.Hosting
         /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
         public IWebHostBuilder UseSetting(string key, string value)
         {
-            _settings[key] = value;
+            _config[key] = value;
             return this;
         }
 
         /// <summary>
-        /// Specify the <see cref="IConfiguration"/> to be used by the web host. If no configuration is
+        /// Get the setting value from the configuration.
-        /// provided to the builder, the default configuration will be used. 
         /// </summary>
-        /// <param name="configuration">The <see cref="IConfiguration"/> to be used.</param>
+        /// <param name="key">The key of the setting to look up.</param>
-        /// <returns>The <see cref="IWebHostBuilder"/>.</returns>
+        /// <returns>The value the setting currently contains.</returns>
-        public IWebHostBuilder UseConfiguration(IConfiguration configuration)
+        public string GetSetting(string key)
         {
-            _config = configuration;
+            return _config[key];
-            return this;
         }
 
         /// <summary>
@@ -187,15 +170,6 @@ namespace Microsoft.AspNetCore.Hosting
 
         private IServiceCollection BuildHostingServices()
         {
-            // Apply the configuration settings
-            var configuration = _config ?? WebHostConfiguration.GetDefault();
-
-            var mergedConfiguration = new ConfigurationBuilder()
-                                .Add(new IncludedConfigurationProvider(configuration))
-                                .AddInMemoryCollection(_settings)
-                                .Build();
-
-            _config = mergedConfiguration;
             _options = new WebHostOptions(_config);
 
             var services = new ServiceCollection();

src/Microsoft.AspNetCore.Hosting/WebHostBuilderExtensions.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using Microsoft.AspNetCore.Hosting.Internal;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.Extensions.Configuration;
 
@@ -21,6 +22,16 @@ namespace Microsoft.AspNetCore.Hosting
             return builder.UseConfiguration(WebHostConfiguration.GetDefault(args));
         }
 
+        public static IWebHostBuilder UseConfiguration(this IWebHostBuilder builder, IConfiguration configuration)
+        {
+            foreach (var setting in configuration.GetFlattenedSettings())
+            {
+                builder.UseSetting(setting.Key, setting.Value);
+            }
+
+            return builder;
+        }
+
         public static IWebHostBuilder UseCaptureStartupErrors(this IWebHostBuilder hostBuilder, bool captureStartupError)
         {
             return hostBuilder.UseSetting(WebHostDefaults.CaptureStartupErrorsKey, captureStartupError ? "true" : "false");

src/Microsoft.AspNetCore.TestHost/TestServer.cs

@@ -22,7 +22,7 @@ namespace Microsoft.AspNetCore.TestHost
 
         public TestServer(IWebHostBuilder builder)
         {
-            if (!builder.Settings.ContainsKey(WebHostDefaults.CaptureStartupErrorsKey))
+            if (string.IsNullOrEmpty(builder.GetSetting(WebHostDefaults.CaptureStartupErrorsKey)))
             {
                 builder.UseCaptureStartupErrors(false);
             }

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

@@ -124,9 +124,10 @@ namespace Microsoft.AspNetCore.Hosting
         }
 
         [Fact]
-        public void CaptureStartupErrorsByDefault()
+        public void DefaultConfigurationCapturesStartupErrors()
         {
             var hostBuilder = new WebHostBuilder()
+                .UseDefaultConfiguration()
                 .UseServer(new TestServer())
                 .UseStartup<StartupBoom>();
 
@@ -146,6 +147,98 @@ namespace Microsoft.AspNetCore.Hosting
             Assert.Equal("A public method named 'ConfigureProduction' or 'Configure' could not be found in the 'Microsoft.AspNetCore.Hosting.Fakes.StartupBoom' type.", exception.Message);
         }
 
+        [Fact]
+        public void CodeBasedSettingsCodeBasedOverride()
+        {
+            var hostBuilder = new WebHostBuilder()
+                .UseSetting(WebHostDefaults.ServerKey, "ServerA")
+                .UseSetting(WebHostDefaults.ServerKey, "ServerB")
+                .UseServer(new TestServer())
+                .UseStartup<StartupNoServices>();
+            
+            var host = (WebHost)hostBuilder.Build();
+
+            Assert.Equal("ServerB", host.ServerFactoryLocation);
+        }
+
+        [Fact]
+        public void CodeBasedSettingsConfigBasedOverride()
+        {
+            var settings = new Dictionary<string, string>
+            {
+                { WebHostDefaults.ServerKey, "ServerB" }
+            };
+
+            var config = new ConfigurationBuilder()
+                .AddInMemoryCollection(settings)
+                .Build();
+
+            var hostBuilder = new WebHostBuilder()
+                .UseSetting(WebHostDefaults.ServerKey, "ServerA")
+                .UseConfiguration(config)
+                .UseServer(new TestServer())
+                .UseStartup<StartupNoServices>();
+
+            var host = (WebHost)hostBuilder.Build();
+
+            Assert.Equal("ServerB", host.ServerFactoryLocation);
+        }
+
+        [Fact]
+        public void ConfigBasedSettingsCodeBasedOverride()
+        {
+            var settings = new Dictionary<string, string>
+            {
+                { WebHostDefaults.ServerKey, "ServerA" }
+            };
+
+            var config = new ConfigurationBuilder()
+                .AddInMemoryCollection(settings)
+                .Build();
+
+            var hostBuilder = new WebHostBuilder()
+                .UseConfiguration(config)
+                .UseSetting(WebHostDefaults.ServerKey, "ServerB")
+                .UseServer(new TestServer())
+                .UseStartup<StartupNoServices>();
+
+            var host = (WebHost)hostBuilder.Build();
+
+            Assert.Equal("ServerB", host.ServerFactoryLocation);
+        }
+
+        [Fact]
+        public void ConfigBasedSettingsConfigBasedOverride()
+        {
+            var settings = new Dictionary<string, string>
+            {
+                { WebHostDefaults.ServerKey, "ServerA" }
+            };
+
+            var config = new ConfigurationBuilder()
+                .AddInMemoryCollection(settings)
+                .Build();
+
+            var overrideSettings = new Dictionary<string, string>
+            {
+                { WebHostDefaults.ServerKey, "ServerB" }
+            };
+
+            var overrideConfig = new ConfigurationBuilder()
+                .AddInMemoryCollection(overrideSettings)
+                .Build();
+
+            var hostBuilder = new WebHostBuilder()
+                .UseConfiguration(config)
+                .UseConfiguration(overrideConfig)
+                .UseServer(new TestServer())
+                .UseStartup<StartupNoServices>();
+
+            var host = (WebHost)hostBuilder.Build();
+
+            Assert.Equal("ServerB", host.ServerFactoryLocation);
+        }
+
         [Fact]
         public void UseEnvironmentIsNotOverriden()
         {