Adds notes/test about pre building the netcore container

src/Umbraco.Tests.Integration/ContainerTests.cs

@@ -73,6 +73,14 @@ namespace Umbraco.Tests.Integration
         [Test]
         public async Task BuildServiceProvider_Before_Host_Is_Configured()
         {
+            // This is a test to show an anti-pattern used in netcore. This should be avoided in all cases if possible.
+            // There's a thread about this here: https://github.com/dotnet/aspnetcore/issues/14587
+            // For some reason we are not being warned about this with our code analysis since we are using it
+            // in a couple of places but we should really try to see if we can avoid it.
+            // The test below shows how it could be possible to resolve an instance and then re-register it as a factory
+            // so that only one singleton instance is every created, but it's hacky and like Fowler says in that article
+            // it means the container won't be disposed, and maybe other services? not sure.
+
             var umbracoContainer = RuntimeTests.GetUmbracoContainer(out var serviceProviderFactory);
 
             IHostApplicationLifetime lifetime1 = null;

src/Umbraco.Web.BackOffice/AspNetCore/UmbracoCoreServiceCollectionExtensions.cs

@@ -29,6 +29,7 @@ namespace Umbraco.Web.BackOffice.AspNetCore
         /// <returns></returns>
         public static IServiceCollection AddUmbracoConfiguration(this IServiceCollection services)
         {
+            // TODO: We need to avoid this, surely there's a way? See ContainerTests.BuildServiceProvider_Before_Host_Is_Configured
             var serviceProvider = services.BuildServiceProvider();
             var configuration = serviceProvider.GetService<IConfiguration>();
             if (configuration == null)
@@ -129,8 +130,7 @@ namespace Umbraco.Web.BackOffice.AspNetCore
             out ILogger logger, out Configs configs, out IIOHelper ioHelper, out Core.Hosting.IHostingEnvironment hostingEnvironment,
             out IBackOfficeInfo backOfficeInfo, out IProfiler profiler)
         {
-            // TODO: Resolving services before the Host is done configuring this way means that the services resolved
-            // are not going to be the same instances that are going to be used within the application!
+            // TODO: We need to avoid this, surely there's a way? See ContainerTests.BuildServiceProvider_Before_Host_Is_Configured
             var serviceProvider = services.BuildServiceProvider();
 
             var httpContextAccessor = serviceProvider.GetRequiredService<IHttpContextAccessor>();
@@ -148,7 +148,7 @@ namespace Umbraco.Web.BackOffice.AspNetCore
             ioHelper = new IOHelper(hostingEnvironment, globalSettings);
             logger = SerilogLogger.CreateWithDefaultConfiguration(hostingEnvironment,
                 new AspNetCoreSessionIdResolver(httpContextAccessor),
-                // need to build a new service provider since the one already resolved above doesn't have the IRequestCache yet
+                // TODO: We need to avoid this, surely there's a way? See ContainerTests.BuildServiceProvider_Before_Host_Is_Configured
                 () => services.BuildServiceProvider().GetService<IRequestCache>(), coreDebug, ioHelper,
                 new AspNetCoreMarchal());
 

src/Umbraco.Web.Website/AspNetCore/UmbracoWebsiteServiceCollectionExtensions.cs

@@ -19,6 +19,7 @@ namespace Umbraco.Web.Website.AspNetCore
     {
         public static IServiceCollection AddUmbracoWebsite(this IServiceCollection services)
         {
+            // TODO: We need to avoid this, surely there's a way? See ContainerTests.BuildServiceProvider_Before_Host_Is_Configured
             var serviceProvider = services.BuildServiceProvider();
             var configs = serviceProvider.GetService<Configs>();
             var imagingSettings = configs.Imaging();