Worked on AspNetCoreHostingEnvironment.cs

src/Umbraco.Core/Configuration/HealthChecks/TrySkipIisCustomErrorsCheck.cs

@@ -13,13 +13,13 @@ namespace Umbraco.Web.HealthCheck.Checks.Config
         Group = "Configuration")]
     public class TrySkipIisCustomErrorsCheck : AbstractConfigCheck
     {
-        private readonly IHostingEnvironment _hostingEnvironment;
+        private readonly Version _iisVersion;
 
         public TrySkipIisCustomErrorsCheck(ILocalizedTextService textService, IIOHelper ioHelper, ILogger logger,
             IHostingEnvironment hostingEnvironment)
             : base(textService, ioHelper, logger)
         {
-            _hostingEnvironment = hostingEnvironment;
+            _iisVersion = hostingEnvironment.IISVersion;
         }
 
         public override string FilePath => "~/Config/umbracoSettings.config";
@@ -33,7 +33,7 @@ namespace Umbraco.Web.HealthCheck.Checks.Config
             get
             {
                 // beware! 7.5 and 7.5.0 are not the same thing!
-                var recommendedValue = _hostingEnvironment.IISVersion >= new Version("7.5")
+                var recommendedValue = _iisVersion >= new Version("7.5")
                     ? bool.TrueString.ToLower()
                     : bool.FalseString.ToLower();
                 return new List<AcceptableConfiguration> { new AcceptableConfiguration { IsRecommended =  true, Value = recommendedValue } };
@@ -45,7 +45,7 @@ namespace Umbraco.Web.HealthCheck.Checks.Config
             get
             {
                 return TextService.Localize("healthcheck/trySkipIisCustomErrorsCheckSuccessMessage",
-                    new[] { Values.First(v => v.IsRecommended).Value, _hostingEnvironment.IISVersion.ToString() });
+                    new[] { Values.First(v => v.IsRecommended).Value, _iisVersion.ToString() });
             }
         }
 
@@ -54,7 +54,7 @@ namespace Umbraco.Web.HealthCheck.Checks.Config
             get
             {
                 return TextService.Localize("healthcheck/trySkipIisCustomErrorsCheckErrorMessage",
-                    new[] { CurrentValue, Values.First(v => v.IsRecommended).Value, _hostingEnvironment.IISVersion.ToString() });
+                    new[] { CurrentValue, Values.First(v => v.IsRecommended).Value, _iisVersion.ToString() });
             }
         }
 
@@ -63,7 +63,7 @@ namespace Umbraco.Web.HealthCheck.Checks.Config
             get
             {
                 return TextService.Localize("healthcheck/trySkipIisCustomErrorsCheckRectifySuccessMessage",
-                    new[] { Values.First(v => v.IsRecommended).Value, _hostingEnvironment.IISVersion.ToString() });
+                    new[] { Values.First(v => v.IsRecommended).Value, _iisVersion.ToString() });
             }
         }
     }

src/Umbraco.Core/Hosting/IHostingEnvironment.cs

@@ -11,8 +11,6 @@ namespace Umbraco.Core.Hosting
         string LocalTempPath { get; }
         string ApplicationVirtualPath { get; }
 
-        int CurrentDomainId { get; }
-
         bool IsDebugMode { get; }
         /// <summary>
         /// Gets a value indicating whether Umbraco is hosted.

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

@@ -1,4 +1,3 @@
-
 using System;
 using System.IO;
 using Microsoft.AspNetCore.Hosting;
@@ -12,6 +11,7 @@ namespace Umbraco.Web.BackOffice.AspNetCore
     {
         private readonly IHostingSettings _hostingSettings;
         private readonly IWebHostEnvironment _webHostEnvironment;
+        private string _localTempPath;
 
         public AspNetCoreHostingEnvironment(IHostingSettings hostingSettings, IWebHostEnvironment webHostEnvironment)
         {
@@ -19,22 +19,57 @@ namespace Umbraco.Web.BackOffice.AspNetCore
             _webHostEnvironment = webHostEnvironment;
 
             SiteName = webHostEnvironment.ApplicationName;
-            ApplicationPhysicalPath = webHostEnvironment.ContentRootPath;
-            IsHosted = true;
-            ApplicationVirtualPath = "/"; //TODO how to find this, This is a server thing, not application thing.
             ApplicationId = AppDomain.CurrentDomain.Id.ToString();
-            CurrentDomainId = AppDomain.CurrentDomain.Id;
+            ApplicationPhysicalPath = webHostEnvironment.ContentRootPath;
+
+            ApplicationVirtualPath = "/"; //TODO how to find this, This is a server thing, not application thing.
             // IISVersion = HttpRuntime.IISVersion;
+            IsDebugMode =  _hostingSettings.DebugMode;
         }
 
         public string SiteName { get; }
         public string ApplicationId { get; }
         public string ApplicationPhysicalPath { get; }
-        public string LocalTempPath { get; }
+        public string LocalTempPath
+        {
+            get
+            {
+                if (_localTempPath != null)
+                    return _localTempPath;
+
+                switch (_hostingSettings.LocalTempStorageLocation)
+                {
+                    case LocalTempStorage.AspNetTemp:
+                         return _localTempPath = System.IO.Path.Combine(Path.GetTempPath(),ApplicationId,  "UmbracoData");
+
+                    case LocalTempStorage.EnvironmentTemp:
+
+                        // environment temp is unique, we need a folder per site
+
+                        // use a hash
+                        // combine site name and application id
+                        //  site name is a Guid on Cloud
+                        //  application id is eg /LM/W3SVC/123456/ROOT
+                        // the combination is unique on one server
+                        // and, if a site moves from worker A to B and then back to A...
+                        //  hopefully it gets a new Guid or new application id?
+
+                        var hashString = SiteName + "::" + ApplicationId;
+                        var hash = hashString.GenerateHash();
+                        var siteTemp = System.IO.Path.Combine(Environment.ExpandEnvironmentVariables("%temp%"), "UmbracoData", hash);
+
+                        return _localTempPath = siteTemp;
+
+                    //case LocalTempStorage.Default:
+                    //case LocalTempStorage.Unknown:
+                    default:
+                        return _localTempPath = MapPath("~/App_Data/TEMP");
+                }
+            }
+        }
         public string ApplicationVirtualPath { get; }
-        public int CurrentDomainId { get; }
-        public bool IsDebugMode => _hostingSettings.DebugMode;
-        public bool IsHosted { get; }
+        public bool IsDebugMode { get; }
+        public bool IsHosted { get; } = true;
         public Version IISVersion { get; }
         public string MapPath(string path) => Path.Combine(_webHostEnvironment.WebRootPath, path);
 

src/Umbraco.Web/AspNet/AspNetHostingEnvironment.cs

@@ -26,12 +26,9 @@ namespace Umbraco.Web.Hosting
             ApplicationId = HostingEnvironment.ApplicationID;
             ApplicationPhysicalPath = HostingEnvironment.ApplicationPhysicalPath;
             ApplicationVirtualPath = HostingEnvironment.ApplicationVirtualPath;
-            CurrentDomainId = AppDomain.CurrentDomain.Id;
             IISVersion = HttpRuntime.IISVersion;
         }
 
-        public int CurrentDomainId { get; }
-
         public string SiteName { get; }
         public string ApplicationId { get; }
         public string ApplicationPhysicalPath { get; }