#984 single file publish works with Service connectors (#1237)

* changed handling for published single file to silently fail not loading additional dll for #984
* add/update assembly-loading helpers for PublishSingleFile scenarios

---------

Co-authored-by: Tim Hess <thess@vmware.com>

src/Common/src/Common/Reflection/ReflectionHelpers.cs

@@ -304,7 +304,13 @@ private static void TryLoadAssembliesWithAttribute<T>()
         where T : AssemblyContainsTypeAttribute
     {
         var runtimeAssemblies = Directory.GetFiles(RuntimeEnvironment.GetRuntimeDirectory(), "*.dll");
-        using var loadContext = new MetadataLoadContext(new PathAssemblyResolver(AllRelevantPaths(runtimeAssemblies, typeof(T))));
+        var allKnownAssemblyPaths = AllRelevantPaths(runtimeAssemblies, typeof(T));
+        if (!allKnownAssemblyPaths.Any())
+        {
+            return;
+        }
+
+        using var loadContext = new MetadataLoadContext(new PathAssemblyResolver(allKnownAssemblyPaths));
         var loadedAssemblies = AppDomain.CurrentDomain.GetAssemblies();
         var assemblypaths = Directory.EnumerateFiles(AppDomain.CurrentDomain.BaseDirectory).Where(f => f.EndsWith("dll", StringComparison.InvariantCultureIgnoreCase));
         foreach (var assembly in assemblypaths)
@@ -338,26 +344,20 @@ private static void TryLoadAssembliesWithAttribute<T>()
     /// <returns>A list of paths to the runtime, assembly and requested assembly type</returns>
     private static List<string> AllRelevantPaths(string[] runtimeAssemblies, Type attributeType)
     {
-        var toReturn = new List<string>(runtimeAssemblies);
         var executingAssemblyLocation = Assembly.GetExecutingAssembly().Location;
         var typeAssemblyLocation = attributeType.Assembly.Location;
         if (string.IsNullOrEmpty(executingAssemblyLocation) || string.IsNullOrEmpty(typeAssemblyLocation))
         {
-            var baseDirectory = AppDomain.CurrentDomain.BaseDirectory;
-            if (baseDirectory.EndsWith("\\"))
-            {
-                baseDirectory = baseDirectory.Substring(0, baseDirectory.Length - 1);
-            }
-
-            toReturn.Add(baseDirectory);
             Console.WriteLine("File path path information for the assembly containing {0} is missing. Some Steeltoe functionality may not work with PublishSingleFile=true", attributeType.Name);
+            return new List<string>();
         }
         else
         {
-            toReturn.Add(executingAssemblyLocation);
-            toReturn.Add(attributeType.Assembly.Location);
+            return new List<string>(runtimeAssemblies)
+            {
+                executingAssemblyLocation,
+                attributeType.Assembly.Location
+            };
         }
-
-        return toReturn;
     }
 }

src/Connectors/src/CloudFoundry/CloudFoundryConnector.cs

@@ -7,7 +7,7 @@ namespace Steeltoe.Connector.CloudFoundry;
 public static class CloudFoundryConnector
 {
     /// <summary>
-    /// Use this method to ensure Steeltoe.Connector.CloudFoundry is loaded
+    /// Use this method to prevent Steeltoe.Connector.CloudFoundry from being optimized out of the build
     /// </summary>
     public static void EnsureAssemblyIsLoaded()
     {

src/Discovery/src/Consul/Discovery/ConsulDiscoveryClient.cs

@@ -39,6 +39,14 @@ internal ConsulDiscoveryOptions Options
         }
     }
 
+    /// <summary>
+    /// Use this method to prevent Steeltoe.Discovery.Consul from being optimized out of the build
+    /// </summary>
+    public static void EnsureAssemblyIsLoaded()
+    {
+        // no-op
+    }
+
     /// <summary>
     /// Initializes a new instance of the <see cref="ConsulDiscoveryClient"/> class.
     /// </summary>

src/Discovery/src/Eureka/EurekaDiscoveryClient.cs

@@ -36,6 +36,14 @@ public EurekaHttpClientInternal(IOptionsMonitor<EurekaClientOptions> config, ILo
     private readonly IOptionsMonitor<EurekaClientOptions> _configOptions;
     private readonly IServiceInstance _thisInstance;
 
+    /// <summary>
+    /// Use this method to prevent Steeltoe.Discovery.Eureka from being optimized out of the build
+    /// </summary>
+    public static void EnsureAssemblyIsLoaded()
+    {
+        // no-op
+    }
+
     public override IEurekaClientConfig ClientConfig => _configOptions.CurrentValue;
 
     public EurekaDiscoveryClient(

src/Discovery/src/Kubernetes/Discovery/KubernetesDiscoveryClient.cs

@@ -21,6 +21,14 @@ public class KubernetesDiscoveryClient : IDiscoveryClient
     private readonly IOptionsMonitor<KubernetesDiscoveryOptions> _discoveryOptions;
     private readonly DefaultIsServicePortSecureResolver _isServicePortSecureResolver;
 
+    /// <summary>
+    /// Use this method to prevent Steeltoe.Discovery.Kubernetes from being optimized out of the build
+    /// </summary>
+    public static void EnsureAssemblyIsLoaded()
+    {
+        // no-op
+    }
+
     public string Description => "Steeltoe provided Kubernetes native service discovery client";
 
     public IList<string> Services => GetServices(null);