Asp.Net Core 2.0-2.2 Kestrel 不提供静态内容

Question

When running a Asp.Net Core 2.0 (or 2.2) app using IIS express, static files (css, js) are served as expected. However when using command line/Kestrel via "dotnet publish -o [targetDirectory]" and dotnet [website.dll], Kestrel does not serve up any static content. Utilizing browser F12, I see Kestrel returns a 404 error. Looking closer, when entering the file path directly in the browser (localhost:5000/ css /cssfile.css) the file is not displayed but the browser appears to redirect to "localhost:5000/cssfile.css" but still returns a 404 error (note the missing /css/ directory).

I created this project via Visual Studio 2017, and chose the defaults for a new MVC Core 2.0 application (SDK was installed).

I have followed the steps here to enable static files in the program.cs and startup.cs files. These implement "app.UseStaticFiles();" and ".UseContentRoot(Directory.GetCurrentDirectory())". None of the articles found via google seem to help. I have verified dotnet copied the static content to the target directory.

What am I missing? Thanks

// Program.cs
public static IWebHost BuildWebHost(string[] args) => WebHost
   .CreateDefaultBuilder(args)
   .UseStartup<Startup>()
   .Build();

// Startup.cs
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseExceptionHandler("/Error/HandleError");
    app.UseStaticFiles();

    app.UseMvc(routes =>
    {
        routes.MapRoute( name: "default", template: "{controller=User}/{action=Index}/{id?}");
    });
}

Answer 1

I tried so many useless things, this was the fix for me:

WebHost.CreateDefaultBuilder(args)
.UseKestrel()
.UseContentRoot(Directory.GetCurrentDirectory())
.UseIISIntegration()
.UseStartup<Startup>()
.UseWebRoot("E:\\xyz\\wwwroot")
.UseUrls("http://localhost:5050")
    .Build();

Serving static files started working as soon as I added:

.UseWebRoot("E:\\xyz\\wwwroot")

_{I got a conflict on one of my servers running on port 5000, so I specified to start on port 5050.}

---

Update for .Net Core 2.2

For .NET Core 2.2, the following works: .UseWebRoot("wwwroot")

However, a more readable and explicit approach to get the path:

static string webRoot = Path.Combine(AppContext.BaseDirectory, "wwwroot");

and then UseWebRoot(webRoot);

Answer 2

I am unable to reproduce your error using a fresh ASP.NET Core 2.0 project following these steps;

1. md static-test
2. cd static-test
3. dotnet new web
4. Add folder css in wwwroot.
5. Add file site.css in wwwroot/css .
6. Insert app.UseStaticFiles(); at the start of Startup.Configure() method.
7. dotnet publish -o pubweb
8. cd pubweb
9. dotnet .\\static-test.dll
10. Access http://localhost:5000/css/site.css using browser.

dotnet.exe renders the following output in my terminal:

Hosting environment: Production
Content root path: C:\src\static-test\pubweb
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
      Request starting HTTP/1.1 GET http://localhost:5000/css/site.css
info: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[2]
      Sending file. Request path: '/css/site.css'. Physical path: 'C:\src\static-test\pubweb\wwwroot\css\site.css'

As you can see it will successfully serve the css file within a subfolder correctly. Please try the above steps and compare the code and output with your failing project. If it is still failing, please attach the debug info on Request vs. Physical path from Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware above.

Answer 3

For me, the problem was the working directory. I wasn't paying attention to the directory I was in when trying to launch the app with dotnet /var/www/project/project.dll . It automatically uses your current directory as the working directory when you launch the app this way.

I realized this when I looked at a .service file for another project, which has the WorkingDirectory specified:

...
WorkingDirectory=/var/www/project/
ExecStart=/usr/bin/dotnet /var/www/project/project.dll
...

So, either make sure you are in the correct directory when you run your project, or ensure that the WorkingDirectory is properly set in your .service file.

Answer 4

I just ran into a very similar issue. I couldn't get Kestrel to serve up any static content; I had a config that worked fine in .net core 1.1, but it wouldn't work in .net core 2.0.

I debugged through it and the IFileProvider instance used by the static file middleware was NullFileProvider. I had to do this in Startup.cs to get static content served:

app.UseFileServer(
    new FileServerOptions() {
        FileProvider = new PhysicalFileProvider("some_path")
    });

Answer 5

After trial and error I realized that once I begin using Kestrel, the static files web root is suddenly mapped to the bin folder instead of the development folder. To fix this you can do one of two things.

1. You can set all of the static files you want to include to Copy to Output Directory

2. You can remap the root directory to a certain path:

    .UseKestrel(...) .UseWebRoot(@"C:\\MyProject\\wwwroot\\");

I use the wwwroot folder that I develop in so I don't have to ensure all new items get added to Copy to Output Directory.

Answer 6

I have create an new project with asp.net core 2.1 (MVC) with the MS template and then have included a css file animate.css with some animations.

To be able to use it, a href has to be added in _Layout.cshtml
Thereby, I have noted, that MS has "forgotten" to add the environments "Staging" and "Production" So.. if the href is added in the "Development" environment, everything works fine in debugging (IIS Express), but it don't works with a selfhost (and I assume also not on "the real" IIS), as this is not the Development environment and the hrefs's are not set at runtime.
Therefore I have copy -pasted the "Development" environment also for "Staging" and "Production" (see snipped below).

  <environment include="Development">
        <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.css" />
        <link rel="stylesheet" href="~/css/site.css" />
        <link rel="stylesheet" href="~/css/animate.css">
    </environment>
    <environment exclude="Development">
        <link rel="stylesheet" href="https://ajax.aspnetcdn.com/ajax/bootstrap/3.3.7/css/bootstrap.min.css"
              asp-fallback-href="~/lib/bootstrap/dist/css/bootstrap.min.css"
              asp-fallback-test-class="sr-only" asp-fallback-test-property="position" asp-fallback-test-value="absolute" />
        <link rel="stylesheet" href="~/css/site.min.css" asp-append-version="true" />
    </environment>

    @*<environment include="Staging,Production"> -> was missing completely!copy pasted from Development*@
    <environment include="Staging,Production">
        <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.css" />
        <link rel="stylesheet" href="~/css/site.css" />
        <link rel="stylesheet" href="~/css/animate.css">
    </environment>
    <environment exclude="Staging,Production">
        <link rel="stylesheet" href="https://ajax.aspnetcdn.com/ajax/bootstrap/3.3.7/css/bootstrap.min.css"
              asp-fallback-href="~/lib/bootstrap/dist/css/bootstrap.min.css"
              asp-fallback-test-class="sr-only" asp-fallback-test-property="position" asp-fallback-test-value="absolute" />
        <link rel="stylesheet" href="~/css/site.min.css" asp-append-version="true" />
    </environment>
    @*End manually inserted*@

Answer 7

If you're running into this in Docker you need to know that the "root" is based on where you're executing the dotnet command. I'm not sure this makes the most sense, but it is what it is. Where it's easy to get tripped up is you need to make sure your Docker container is in the correct directory before executing the command.

WORKDIR /app
# Example publish/build command:
RUN dotnet publish -o out
# Your publish folder is /app/out so...
# ENTRYPOINT ["dotnet", "/app/out/myapp.dll"]
# will run but you'll get 404s on all your static content. 
# Instead use:
WORKDIR /app/out
ENTRYPOINT ["dotnet", "myapp.dll"]

Don't use my script as an example of a proper Docker publish script. It's just an example.

Answer 8

I had a similar issue. (I developed in Win and hosted on Linux, in case it makes a difference). Just a few files worked (mostly default ones), but my own content caused 404.

The culprit was: capitals in file and folder names didn't work for me . Converted everything to lower case and it works fine.

Answer 9

Had the same problem in .NET Core 2.2 MVC, running it as self-contained windows service with "Local system" user.

The problem is that windows services use default directory in "C:\\Windows\\System32", so you need to define new path:

.UseWebRoot(@"C:\MyProject\wwwroot\");

Here is code I use for detecting path in runtime:

// Find app directory.
var isService = !(Debugger.IsAttached || args.Contains("--console"));
var currentDir = Directory.GetCurrentDirectory();
if (isService)
{
    var pathToExe = Process.GetCurrentProcess().MainModule.FileName;
    currentDir = Path.GetDirectoryName(pathToExe);
}

// Configure web host
var host = WebHost.CreateDefaultBuilder(args)
        .UseKestrel()
        .UseContentRoot(currentDir)
        .UseWebRoot(Path.Combine(currentDir, "wwwroot"));
        .UseStartup<Startup>()
        .Build();

// Run.
if (isService)
{
    host.RunAsService();
}
else
{
    host.Run();
}

Answer 10

Please check whether those static files are present within the below tags.

<environment include="Development">
</environment>

As you have Published, if the static files are present inside the include Development , then they will not be present in the Published folder. Also, Check View Source and see whether those links are present or not.