Update static file docs and log if WebRootPath is not found

src/Hosting/Abstractions/src/IWebHostEnvironment.cs

@@ -13,11 +13,13 @@ public interface IWebHostEnvironment : IHostEnvironment
 {
     /// <summary>
     /// Gets or sets the absolute path to the directory that contains the web-servable application content files.
+    /// This defaults to the 'wwwroot' subfolder.
     /// </summary>
     string WebRootPath { get; set; }
 
     /// <summary>
     /// Gets or sets an <see cref="IFileProvider"/> pointing at <see cref="WebRootPath"/>.
+    /// This defaults to referencing files from the 'wwwroot' subfolder.
     /// </summary>
     IFileProvider WebRootFileProvider { get; set; }
 }

src/Middleware/Middleware.slnf

@@ -114,6 +114,7 @@
       "src\\Middleware\\WebSockets\\test\\UnitTests\\Microsoft.AspNetCore.WebSockets.Tests.csproj",
       "src\\Middleware\\perf\\Microbenchmarks\\Microsoft.AspNetCore.WebSockets.Microbenchmarks.csproj",
       "src\\Middleware\\perf\\ResponseCaching.Microbenchmarks\\Microsoft.AspNetCore.ResponseCaching.Microbenchmarks.csproj",
+      "src\\ObjectPool\\src\\Microsoft.Extensions.ObjectPool.csproj",
       "src\\Security\\Authorization\\Core\\src\\Microsoft.AspNetCore.Authorization.csproj",
       "src\\Servers\\Connections.Abstractions\\src\\Microsoft.AspNetCore.Connections.Abstractions.csproj",
       "src\\Servers\\HttpSys\\src\\Microsoft.AspNetCore.Server.HttpSys.csproj",
@@ -122,7 +123,9 @@
       "src\\Servers\\IIS\\IntegrationTesting.IIS\\src\\Microsoft.AspNetCore.Server.IntegrationTesting.IIS.csproj",
       "src\\Servers\\Kestrel\\Core\\src\\Microsoft.AspNetCore.Server.Kestrel.Core.csproj",
       "src\\Servers\\Kestrel\\Kestrel\\src\\Microsoft.AspNetCore.Server.Kestrel.csproj",
-      "src\\Servers\\Kestrel\\Transport.Sockets\\src\\Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.csproj"
+      "src\\Servers\\Kestrel\\Transport.Quic\\src\\Microsoft.AspNetCore.Server.Kestrel.Transport.Quic.csproj",
+      "src\\Servers\\Kestrel\\Transport.Sockets\\src\\Microsoft.AspNetCore.Server.Kestrel.Transport.Sockets.csproj",
+      "src\\WebEncoders\\src\\Microsoft.Extensions.WebEncoders.csproj"
     ]
   }
 }

src/Middleware/StaticFiles/src/DefaultFilesExtensions.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.StaticFiles;
 using Microsoft.Extensions.Options;
@@ -17,6 +18,10 @@ public static class DefaultFilesExtensions
     /// </summary>
     /// <param name="app"></param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseDefaultFiles(this IApplicationBuilder app)
     {
         if (app == null)
@@ -33,6 +38,10 @@ public static IApplicationBuilder UseDefaultFiles(this IApplicationBuilder app)
     /// <param name="app"></param>
     /// <param name="requestPath">The relative request path.</param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseDefaultFiles(this IApplicationBuilder app, string requestPath)
     {
         if (app == null)

src/Middleware/StaticFiles/src/DirectoryBrowserExtensions.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.StaticFiles;
 using Microsoft.Extensions.Options;
@@ -17,6 +18,10 @@ public static class DirectoryBrowserExtensions
     /// </summary>
     /// <param name="app"></param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseDirectoryBrowser(this IApplicationBuilder app)
     {
         if (app == null)
@@ -33,6 +38,10 @@ public static IApplicationBuilder UseDirectoryBrowser(this IApplicationBuilder a
     /// <param name="app"></param>
     /// <param name="requestPath">The relative request path.</param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseDirectoryBrowser(this IApplicationBuilder app, string requestPath)
     {
         if (app == null)

src/Middleware/StaticFiles/src/FileServerExtensions.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Builder;
@@ -16,6 +17,10 @@ public static class FileServerExtensions
     /// </summary>
     /// <param name="app"></param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseFileServer(this IApplicationBuilder app)
     {
         if (app == null)
@@ -32,6 +37,10 @@ public static IApplicationBuilder UseFileServer(this IApplicationBuilder app)
     /// <param name="app"></param>
     /// <param name="enableDirectoryBrowsing">Should directory browsing be enabled?</param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseFileServer(this IApplicationBuilder app, bool enableDirectoryBrowsing)
     {
         if (app == null)
@@ -51,6 +60,10 @@ public static IApplicationBuilder UseFileServer(this IApplicationBuilder app, bo
     /// <param name="app"></param>
     /// <param name="requestPath">The relative request path.</param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseFileServer(this IApplicationBuilder app, string requestPath)
     {
         if (app == null)

src/Middleware/StaticFiles/src/Infrastructure/SharedOptionsBase.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.FileProviders;
 
@@ -32,6 +33,7 @@ protected SharedOptionsBase(SharedOptions sharedOptions)
 
     /// <summary>
     /// The relative request path that maps to static resources.
+    /// This defaults to the site root '/'.
     /// </summary>
     public PathString RequestPath
     {
@@ -42,6 +44,10 @@ public PathString RequestPath
     /// <summary>
     /// The file system used to locate resources
     /// </summary>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public IFileProvider? FileProvider
     {
         get { return SharedOptions.FileProvider; }

src/Middleware/StaticFiles/src/LoggerExtensions.cs

@@ -58,4 +58,8 @@ public static void FileServed(this ILogger logger, string virtualPath, string ph
 
     [LoggerMessage(14, LogLevel.Debug, "The file transmission was cancelled", EventName = "WriteCancelled")]
     public static partial void WriteCancelled(this ILogger logger, Exception ex);
+
+    [LoggerMessage(16, LogLevel.Warning,
+        "The WebRootPath was not found: {WebRootPath}. Static files may be unavailable.", EventName = "WebRootPathNotFound")]
+    public static partial void WebRootPathNotFound(this ILogger logger, string webRootPath);
 }

src/Middleware/StaticFiles/src/StaticFileExtensions.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.StaticFiles;
 using Microsoft.Extensions.Options;
@@ -17,6 +18,10 @@ public static class StaticFileExtensions
     /// </summary>
     /// <param name="app"></param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseStaticFiles(this IApplicationBuilder app)
     {
         if (app == null)
@@ -33,6 +38,10 @@ public static IApplicationBuilder UseStaticFiles(this IApplicationBuilder app)
     /// <param name="app"></param>
     /// <param name="requestPath">The relative request path.</param>
     /// <returns></returns>
+    /// <remarks>
+    /// Files are served from the path specified in <see cref="IWebHostEnvironment.WebRootPath"/>
+    /// or <see cref="IWebHostEnvironment.WebRootFileProvider"/> which defaults to the 'wwwroot' subfolder.
+    /// </remarks>
     public static IApplicationBuilder UseStaticFiles(this IApplicationBuilder app, string requestPath)
     {
         if (app == null)

src/Middleware/StaticFiles/src/StaticFileMiddleware.cs

@@ -57,6 +57,12 @@ public StaticFileMiddleware(RequestDelegate next, IWebHostEnvironment hostingEnv
         _fileProvider = _options.FileProvider ?? Helpers.ResolveFileProvider(hostingEnv);
         _matchUrl = _options.RequestPath;
         _logger = loggerFactory.CreateLogger<StaticFileMiddleware>();
+
+        // See HostingEnvironmentExtensions.Initialize
+        if (_fileProvider is NullFileProvider && _fileProvider == hostingEnv.WebRootFileProvider)
+        {
+            _logger.WebRootPathNotFound(Path.GetFullPath(Path.Combine(hostingEnv.ContentRootPath, hostingEnv.WebRootPath ?? "wwwroot")));
+        }
     }
 
     /// <summary>

src/Middleware/StaticFiles/test/UnitTests/StaticFileMiddlewareTests.cs

@@ -17,12 +17,13 @@
 
 namespace Microsoft.AspNetCore.StaticFiles;
 
-public class StaticFileMiddlewareTests
+public class StaticFileMiddlewareTests : LoggedTest
 {
     [Fact]
     public async Task ReturnsNotFoundWithoutWwwroot()
     {
         using var host = new HostBuilder()
+            .ConfigureServices(AddTestLogging)
             .ConfigureWebHost(webHostBuilder =>
             {
                 webHostBuilder
@@ -38,6 +39,9 @@ public async Task ReturnsNotFoundWithoutWwwroot()
 
         Assert.Equal(HttpStatusCode.NotFound, response.StatusCode);
         Assert.Null(response.Headers.ETag);
+
+        Assert.Contains(TestSink.Writes, w => w.Message.Contains("The WebRootPath was not found")
+            && w.Message.Contains("Static files may be unavailable."));
     }
 
     [ConditionalFact]
@@ -52,6 +56,7 @@ public async Task ReturnsNotFoundForBrokenSymlink()
         try
         {
             using var host = new HostBuilder()
+            .ConfigureServices(AddTestLogging)
             .ConfigureWebHost(webHostBuilder =>
             {
                 webHostBuilder
@@ -83,6 +88,7 @@ public async Task ReturnsNotFoundIfSendFileThrows()
             .ThrowsAsync(new FileNotFoundException());
         mockSendFile.Setup(m => m.Stream).Returns(Stream.Null);
         using var host = new HostBuilder()
+            .ConfigureServices(AddTestLogging)
             .ConfigureWebHost(webHostBuilder =>
             {
                 webHostBuilder