Merge branch 'v9/dev' into v10/feature/merge-v9-dev

# Conflicts:
#	build/templates/UmbracoPackage/.template.config/template.json
#	build/templates/UmbracoProject/.template.config/template.json
#	src/Directory.Build.props
#	src/Umbraco.Core/Actions/ActionAssignDomain.cs
#	src/Umbraco.Infrastructure/DependencyInjection/UmbracoBuilder.Services.cs
#	src/Umbraco.Web.BackOffice/Controllers/AuthenticationController.cs
#	src/Umbraco.Web.BackOffice/DependencyInjection/UmbracoBuilderExtensions.cs
#	src/Umbraco.Web.Common/Extensions/ApplicationBuilderExtensions.cs

src/Umbraco.Web.Common/Extensions/ApplicationBuilderExtensions.cs

@@ -1,18 +1,20 @@
 using System;
 using System.IO;
+using Dazinator.Extensions.FileProviders.PrependBasePath;
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Serilog.Context;
 using StackExchange.Profiling;
 using Umbraco.Cms.Core;
 using Umbraco.Cms.Core.Configuration.Models;
-using Umbraco.Cms.Core.Hosting;
 using Umbraco.Cms.Core.Logging.Serilog.Enrichers;
 using Umbraco.Cms.Core.Services;
 using Umbraco.Cms.Web.Common.ApplicationBuilder;
 using Umbraco.Cms.Web.Common.Middleware;
 using Umbraco.Cms.Web.Common.Plugins;
+using IHostingEnvironment = Umbraco.Cms.Core.Hosting.IHostingEnvironment;
 
 namespace Umbraco.Extensions
 {
@@ -94,7 +96,8 @@ namespace Umbraco.Extensions
                 throw new ArgumentNullException(nameof(app));
             }
 
-            if (!app.UmbracoCanBoot()) return app;
+            if (!app.UmbracoCanBoot())
+                return app;
 
             app.UseMiddleware<UmbracoRequestLoggingMiddleware>();
 
@@ -109,25 +112,21 @@ namespace Umbraco.Extensions
         public static IApplicationBuilder UseUmbracoPluginsStaticFiles(this IApplicationBuilder app)
         {
             var hostingEnvironment = app.ApplicationServices.GetRequiredService<IHostingEnvironment>();
-            var umbracoPluginSettings = app.ApplicationServices.GetRequiredService<IOptionsMonitor<UmbracoPluginSettings>>();
 
             var pluginFolder = hostingEnvironment.MapPathContentRoot(Constants.SystemDirectories.AppPlugins);
-
-            // Ensure the plugin folder exists
-            Directory.CreateDirectory(pluginFolder);
-
-            var fileProvider = new UmbracoPluginPhysicalFileProvider(
-                pluginFolder,
-                umbracoPluginSettings);
-
-            app.UseStaticFiles(new StaticFileOptions
+            if (Directory.Exists(pluginFolder))
             {
-                FileProvider = fileProvider,
-                RequestPath = Constants.SystemDirectories.AppPlugins
-            });
+                var umbracoPluginSettings = app.ApplicationServices.GetRequiredService<IOptionsMonitor<UmbracoPluginSettings>>();
+
+                var pluginFileProvider = new UmbracoPluginPhysicalFileProvider(
+                    pluginFolder,
+                    umbracoPluginSettings);
+
+                IWebHostEnvironment webHostEnvironment = app.ApplicationServices.GetService<IWebHostEnvironment>();
+                webHostEnvironment.WebRootFileProvider = webHostEnvironment.WebRootFileProvider.ConcatComposite(new PrependBasePathFileProvider(Constants.SystemDirectories.AppPlugins, pluginFileProvider));
+            }
 
             return app;
         }
     }
-
 }

src/Umbraco.Web.Common/Extensions/FileProviderExtensions.cs

@@ -0,0 +1,19 @@
+using System.Linq;
+using Microsoft.Extensions.FileProviders;
+
+namespace Umbraco.Extensions
+{
+    internal static class FileProviderExtensions
+    {
+        public static IFileProvider ConcatComposite(this IFileProvider fileProvider, params IFileProvider[] fileProviders)
+        {
+            var existingFileProviders = fileProvider switch
+            {
+                CompositeFileProvider compositeFileProvider => compositeFileProvider.FileProviders,
+                _ => new[] { fileProvider }
+            };
+
+            return new CompositeFileProvider(existingFileProviders.Concat(fileProviders));
+        }
+    }
+}

src/Umbraco.Web.Common/Extensions/HttpRequestExtensions.cs

@@ -1,9 +1,12 @@
-using System.IO;
+using System;
+using System.IO;
 using System.Net;
 using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.DependencyInjection;
+using Umbraco.Cms.Core.Configuration.Models;
 using Umbraco.Cms.Core.Routing;
 
 namespace Umbraco.Extensions
@@ -107,5 +110,31 @@ namespace Umbraco.Extensions
                 return result;
             }
         }
+
+        /// <summary>
+        /// Gets the application URI, will use the one specified in settings if present
+        /// </summary>
+        public static Uri GetApplicationUri(this HttpRequest request, WebRoutingSettings routingSettings)
+        {
+            if (request == null)
+            {
+                throw new ArgumentNullException(nameof(request));
+            }
+
+            if (routingSettings == null)
+            {
+                throw new ArgumentNullException(nameof(routingSettings));
+            }
+
+            if (string.IsNullOrEmpty(routingSettings.UmbracoApplicationUrl))
+            {
+                var requestUri = new Uri(request.GetDisplayUrl());
+
+                // Create a new URI with the relative uri as /, this ensures that only the base path is returned.
+                return new Uri(requestUri, "/");
+            }
+
+            return new Uri(routingSettings.UmbracoApplicationUrl);
+        }
     }
 }