AzureBlobFileProvider

Azure Blob Storage file provider (IFileProvider) for ASP.NET Core.

Installation

Install-Package WaterTrans.AzureBlobFileProvider

Features

• Serve the files in the blob container as static files.
• Download the blob item to the local cache and respond from the local cache for the specified number of seconds.
• The local cache can be ignored by query parameter.
• The location of the local cache directory can be specified.

Usage

Configure access to your Blob Storage via storage account connection string or SAS token.

Below is the usage example for both flows - where access to files from Blob Storage is enabled on the /files route (including directory browsing in the browser).

Connection string

    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            // ConnectionString
            services.AddAzureBlobFileProvider(options =>
            {
                options.ConnectionString = "UseDevelopmentStorage=true";
                options.ContainerName = "files";
                options.LocalCacheTimeout = 300;
            });
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            var blobFileProvider = app.ApplicationServices.GetRequiredService<AzureBlobFileProvider>();

            app.UseStaticFiles(new StaticFileOptions()
            {
                FileProvider = blobFileProvider,
                RequestPath = "/files",
                OnPrepareResponse = ctx => ctx.Context.Response.Headers.Append("Cache-Control", $"public, max-age=300")
            });

            app.UseDirectoryBrowser(new DirectoryBrowserOptions
            {
                FileProvider = blobFileProvider,
                RequestPath = "/files"
            });

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("<a href='files'>files</a>");
                });
            });
        }
    }

Token (need to provide the URL of the storage separately)

    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            // SAS (ServiceUri + Token)
            services.AddAzureBlobFileProvider(options =>
            {
                options.ServiceUri = new System.Uri("https://youraccount.blob.core.windows.net");
                options.Token = "?sv=2020-08-04&ss=b&srt=co&sp=rltfx&se=2021-01-01T00:00:00Z&st=2021-01-02T00:00:00Z&spr=https&sig=xxxxxxxxxxxxxxxxxxxxxx%2Bx%2Fxx%2Bxxxxxxxxxxxxxxx%3D";
                options.ContainerName = "files";
                options.LocalCacheTimeout = 300;
            });
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            var blobFileProvider = app.ApplicationServices.GetRequiredService<AzureBlobFileProvider>();

            app.UseStaticFiles(new StaticFileOptions()
            {
                FileProvider = blobFileProvider,
                RequestPath = "/files",
                OnPrepareResponse = ctx => ctx.Context.Response.Headers.Append("Cache-Control", $"public, max-age=300")
            });

            app.UseDirectoryBrowser(new DirectoryBrowserOptions
            {
                FileProvider = blobFileProvider,
                RequestPath = "/files"
            });

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapGet("/", async context =>
                {
                    await context.Response.WriteAsync("<a href='files'>files</a>");
                });
            });
        }
    }

In case both ConnectionString and Token are present, connection string is given the preference.

Note

• Blob items that contain invalid file path characters will be escaped and stored in the local cache.
• If the local cache directory is omitted, the following directory will be used.
  Path.Combine(Path.GetTempPath(), "AzureBlobFileProvider", StorageAccountName, ContainerName)
• You can ignore the local cache by giving the query parameter as follows.
  /files/favicon.ico?ignoreCache=true