Custom File Systems (IFileSystem)

A guide to creating custom file systems in Umbraco

Media Filesystem

Before considering a custom media file system, be sure to first read about the configuration options for UmbracoMediaPath and UmbracoMediaPhysicalRootPath in the configuration reference docs. These configurations may save you from creating your own media file system entirely.

By default, Umbraco uses an instance of PhysicalFileSystem to handle the storage location of the media archive (wwwroot/media).

This can be configured by composition:

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Core.Hosting;
using Umbraco.Cms.Core.IO;
using Umbraco.Cms.Infrastructure.DependencyInjection;

namespace UmbracoExamples.Composition;

public class SetMediaFileSystemComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
    {
        builder.SetMediaFileSystem((factory) =>
        {
            IHostingEnvironment hostingEnvironment = factory.GetRequiredService<IHostingEnvironment>();
            var folderLocation = "~/CustomMediaFolder";
            var rootPath = hostingEnvironment.MapPathWebRoot(folderLocation);
            var rootUrl = hostingEnvironment.ToAbsolute(folderLocation);

            return new PhysicalFileSystem(
                factory.GetRequiredService<IIOHelper>(),
                hostingEnvironment,
                factory.GetRequiredService<ILogger<PhysicalFileSystem>>(),
                rootPath,
                rootUrl);
        });
    }
}

When creating a PhysicalFileSystem it takes some dependencies like IIOHelper, but the last two parameters are what we're interested in.

The rootPath is where your media will be stored on the disk. Since netcore by default stores files in the wwwroot, we must put our desired folder somewhere within wwwroot to ensure that we use hostingEnvironment.MapPathWebRoot(~/CustomMediaFolder). The ~ will be mapped to your wwwroot folder, so the final rootPath will be your/project/path/wwwroot/CustomMediaFolder. The ~ is therefore important.

The rootUrl is the base URL that your media files will be served from. In this case, your image URL could look something like mysite.com/CustomMediaFolder/MyAwesomePicture.png. Again the ~ is important. With the code sample above, the rootUrl must map to the same physical location as rootPath, otherwise, you will get 404's for your images.

Storing media outside the webroot

A custom media file system is not the right tool for storing media on a physical or network path outside wwwroot. Use the UmbracoMediaPhysicalRootPath setting instead:

{
  "Umbraco": {
    "CMS": {
      "Global": {
        "UmbracoMediaPath": "~/media",
        "UmbracoMediaPhysicalRootPath": "C:\\storage\\umbracoMedia"
      }
    }
  }
}

Umbraco builds a PhysicalFileSystem from these settings, exactly as in the sample above. It also composes the folder into the webroot file provider for you. This keeps both static file serving and image processing working. See FileSystemProviders Configuration for details.

Do not register the media folder as an additional static file provider. A pattern sometimes used for this scenario is to add a PhysicalFileProvider for the media folder in Program.cs:

// Do not do this - it silently disables image resizing.
app.UseStaticFiles(new StaticFileOptions
    {
        FileProvider = new PhysicalFileProvider(Path.Combine("C:", "storage", "umbracoMedia")),
        RequestPath = "/CustomPath"
    });

There are two problems with this:

• Umbraco registers the ImageSharp middleware inside app.UseUmbraco(). A static file middleware registered before that call handles the request first and ignores the querystring, so ?width=500 returns the full-size original.
• ImageSharp resolves images only through the webroot file provider. Files served from a separate PhysicalFileProvider are invisible to it, so resizing still does not work even if the registration is moved after app.UseUmbraco().

Every image is then served at its original size, including backoffice thumbnails. To check whether a site is affected, request an image with and without a resizing querystring. ?width=50 must return a smaller response than the same URL without the querystring.

Reserve a custom media file system for storage that is genuinely of a different kind, such as Azure Blob Storage or Amazon S3.

Creating a custom file system

You can replace PhysicalFileSystem with a custom file system implementation - eg. if you want your media files stored on Amazon S3 or elsewhere outside your site.

To achieve this, you must first create your own file system by implementing the interfaces IFileSystem and IFileProviderFactory (the interfaces that are implemented by PhysicalFileSystem).

Implementing IFileProviderFactory allows Umbraco to compose your media file system into the webroot file provider during startup. It is mounted at the URL configured in UmbracoMediaPath.

Without it, Umbraco cannot serve or process media from your file system through that path. Image processing resolves media only through the webroot file provider.

You then replace the media filesystem by composition using IUmbracoBuilder.SetMediaFileSystem(...) (as is demonstrated in the paragraphs above), but instead of returning a PhysicalFileSystem, you return your own file system implementation.

For inspiration on building a custom file system, have a look at the Azure Blob Storage file system implementation.

Accessing the media file system from code

UmbracoAuthorizedApiController has been removed from Umbraco 14. UseManagementApiControllerBase class instead.

Read the Creating a Backoffice API article for a comprehensive guide to writing APIs for the Management API.

Since the default media file system can be swapped with custom implementations, you should never access the implementation directly. Umbraco uses a manager class called MediaFileManager. You can get a reference to this manager class via dependency injection in the constructor for your custom class or controller:

public class ImagesController : UmbracoAuthorizedApiController
{
    private readonly MediaFileManager _mediaFileManager;

    public ImagesController(MediaFileManager mediaFileManager)
    {
        _mediaFileManager = mediaFileManager;
    }

{...}

You can then access the configured file system provider through _mediaFileManager.FileSystem, which is the same way Umbraco will access the file system provider.

MediaPath Scheme

The MediaPath Scheme defines the current set of rules that decide the format of the Media Path when it is saved into the media archive wherever it is located.

By default the MediaPath scheme used by Umbraco is the UniqueMediaPathScheme this generates a 'folder' to place the uploaded image in, for example:

/media/dozdrg2f/mylovelyimage.jpg

/media is defined by the PhysicalFileSystem and dozdrg2f is generated by the UniqueMediaPathScheme.

The folder generated by UniqueMediaPathScheme is not strictly unique, as it's based on the first eight characters of the GUID for the media item. In practice, with randomly generated GUIDs, a collision is unlikely.

There is an increased possibility of generating colliding paths if creating media programmatically and setting keys using version 7 "ordered" GUIDs via Guid.CreateVersion7(). As such these should be avoided. UniqueMediaPathScheme will throw an exception if it detects they have been used. Any manually created keys should use Guid.NewGuid().

You can create your own logic for the path by implementing IMediaPathScheme and setting it during composition with:

builder.Services.AddUnique<IMediaPathScheme, MyCustomMediaPathScheme>();

Other IFileSystems

Umbraco also registers instances of PhysicalFileSystem for the following parts of Umbraco that persist to 'files':

• PartialViewsFileSystem
• StylesheetsFileSystem
• ScriptsFileSystem
• MvcViewsFileSystem

These are accessible via dependency injection.

IFileSystem, MediaFileManager, and FileSystems are located in the Umbraco.Cms.Core.IO namespace.

Stylesheet Filesystem

Like with the media file system it is also possible to replace the stylesheet filesystem with your own implementation of IFileSystem in a composer. It's important to note here that, unlike media file system, you cannot replace the filesystem with a PhysicalFileSystem using a different root path or root URL, this will not work, and will cause issues since the root path is coupled to the virtual path, given by the frontend, e.g. /css/MyBeautifulStyle.css.

When replacing the stylesheet filesystem, you don't need to register it, since it's only available through Filesystems, what you need to do instead is configure the FileSystems to use your implementation for the StylesheetsFileSystem.

The IUmbracoBuilder has an extension method for configuring the FileSystems, you need to invoke this method with an action that accepts an IServiceProvider and the FileSystems you will configure, configuring the FileSystems can look like this:

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.Configuration.Models;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Core.Hosting;
using Umbraco.Cms.Core.IO;
using Umbraco.Cms.Infrastructure.DependencyInjection;

namespace UmbracoExamples.Composition;

public class FileSystemComposer : IComposer
{
    public void Compose(IUmbracoBuilder builder)
    {
        builder.ConfigureFileSystems((factory, systems) =>
        {
            IIOHelper ioHelper = factory.GetRequiredService<IIOHelper>();
            IHostingEnvironment hostingEnvironment = factory.GetRequiredService<IHostingEnvironment>();
            ILogger<PhysicalFileSystem> logger = factory.GetRequiredService<ILogger<PhysicalFileSystem>>();
            GlobalSettings settings = factory.GetRequiredService<IOptions<GlobalSettings>>().Value;

            var path = settings.UmbracoCssPath;
            var rootPath = hostingEnvironment.MapPathWebRoot(path);
            var rootUrl = hostingEnvironment.ToAbsolute(path);
            var fileSystem = new YourFileSystemImplementation(ioHelper, hostingEnvironment, logger, rootPath, rootUrl);

            systems.SetStylesheetFilesystem(fileSystem);
        });
    }
}

Where YourFileSystemImplementation is a class that implements IFileSystem. This should always be done in a composer, since we do not recommend trying to change filesystems on the fly.

After the SetStylesheetFileSystem method has run, FileSystems.StylesheetsFileSystem will return the instance that was created in the ConfigureFileSystems extension method.

Custom providers

There is an Azure Blob Storage provider:

• Azure Blob Storage