[release/9.1] Update Dcp out of date error message (#7566)

* Update Dcp out of date error message

Remove references to the workload and instead compute the current package version and tell the user to reference the version corresponding with Aspire.Hosting.

Fix #7484

Related Work Items: #7

* Revert unnecessary change

---------

Co-authored-by: Eric Erhardt <[email protected]>

src/Aspire.Hosting/Dcp/DcpDependencyCheck.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Globalization;
+using System.Reflection;
 using System.Text;
 using System.Text.Json;
 using System.Text.RegularExpressions;
@@ -161,7 +162,8 @@ private static void EnsureDcpVersion(DcpInfo dcpInfo)
                 {
                     throw new DistributedApplicationException(string.Format(
                         CultureInfo.InvariantCulture,
-                        Resources.DcpVersionCheckTooLowMessage
+                        Resources.DcpVersionCheckTooLowMessage,
+                        GetCurrentPackageVersion(typeof(DcpDependencyCheck).Assembly)
                     ));
                 }
 
@@ -174,6 +176,35 @@ private static void EnsureDcpVersion(DcpInfo dcpInfo)
         }
     }
 
+    private static string GetCurrentPackageVersion(Assembly assembly)
+    {
+        // The package version is stamped into the assembly's AssemblyInformationalVersionAttribute at build time, followed by a '+' and
+        // the commit hash, e.g.:
+        // [assembly: AssemblyInformationalVersion("9.1.0-preview.1.25111.1+ad18db0213e9db8209bca0feb83fc801f34634f5)]
+
+        var version = assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion;
+
+        if (version is not null)
+        {
+            var plusIndex = version.IndexOf('+');
+
+            if (plusIndex > 0)
+            {
+                return version[..plusIndex];
+            }
+
+            return version;
+        }
+
+        // Fallback to the first 3 parts of the assembly version
+        if (Version.TryParse(assembly.GetCustomAttribute<AssemblyVersionAttribute>()?.Version, out var assemblyVersion))
+        {
+            return assemblyVersion.ToString(3);
+        }
+
+        return "<unknown>";
+    }
+
     internal static void CheckDcpInfoAndLogErrors(ILogger logger, DcpOptions options, DcpInfo dcpInfo, bool throwIfUnhealthy = false)
     {
         var containerRuntime = options.ContainerRuntime;

src/Aspire.Hosting/Properties/Resources.resx

@@ -140,7 +140,7 @@ See https://aka.ms/dotnet/aspire/containers for more details on supported contai
     <value>Application orchestrator dependency check returned an error: {0}</value>
   </data>
   <data name="DcpVersionCheckTooLowMessage" xml:space="preserve">
-    <value>Newer version of .NET Aspire workload is required to run the application. Run 'dotnet workload update' to get it.</value>
+    <value>Newer version of the Aspire.Hosting.AppHost package is required to run the application. Ensure you are referencing at least version '{0}'.</value>
   </data>
   <data name="LaunchSettingsFileDoesNotContainProfileExceptionMessage" xml:space="preserve">
     <value>Launch settings file does not contain '{0}' profile.</value>
@@ -151,4 +151,4 @@ See https://aka.ms/dotnet/aspire/containers for more details on supported contai
   <data name="ProjectFileNotFoundExceptionMessage" xml:space="preserve">
     <value>Project file '{0}' was not found.</value>
   </data>
-</root>
+</root>