Do not add a default address

Author: Tratcher

src/Servers/HttpSys/samples/QueueSharing/Program.cs

@@ -40,7 +40,11 @@ public static void Main(string[] args)
                 {
                     webHost.UseHttpSys(options =>
                     {
-                        options.UrlPrefixes.Add("http://localhost:5000");
+                        // Skipping this to ensure the server works without any prefixes in attach mode.
+                        if (mode != RequestQueueMode.Attach)
+                        {
+                            options.UrlPrefixes.Add("http://localhost:5002");
+                        }
                         options.RequestQueueName = "QueueName";
                         options.RequestQueueMode = mode;
                         options.MaxAccepts = 1; // Better load rotation between instances.

src/Servers/HttpSys/src/MessagePump.cs

@@ -112,13 +112,14 @@ public Task StartAsync<TContext>(IHttpApplication<TContext> application, Cancell
                     Listener.Options.UrlPrefixes.Add(value);
                 }
             }
-            else
+            else if (Listener.RequestQueue.Created)
             {
                 LogHelper.LogDebug(_logger, $"No listening endpoints were configured. Binding to {Constants.DefaultServerAddress} by default.");
 
                 _serverAddresses.Addresses.Add(Constants.DefaultServerAddress);
                 Listener.Options.UrlPrefixes.Add(Constants.DefaultServerAddress);
             }
+            // else // Attaching to an existing queue, don't add a default.
 
             // Can't call Start twice
             Contract.Assert(_application == null);

src/Servers/HttpSys/test/FunctionalTests/ServerTests.cs

@@ -11,6 +11,7 @@
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Hosting.Server.Features;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.HttpSys.Internal;
 using Microsoft.AspNetCore.Testing;
@@ -625,6 +626,25 @@ public async Task Server_StopAsyncCalledWithNoRequests_Success()
             }
         }
 
+        [ConditionalFact]
+        public async Task Server_AttachToExistingQueue_NoIServerAddresses_NoDefaultAdded()
+        {
+            var queueName = Guid.NewGuid().ToString();
+            using var server = Utilities.CreateHttpServer(out var address, httpContext => Task.CompletedTask, options =>
+            {
+                options.RequestQueueName = queueName;
+            });
+            using var attachedServer = Utilities.CreatePump(options =>
+            {
+                options.RequestQueueName = queueName;
+                options.RequestQueueMode = RequestQueueMode.Attach;
+            });
+            await attachedServer.StartAsync(new DummyApplication(context => Task.CompletedTask), default);
+            var addressesFeature = attachedServer.Features.Get<IServerAddressesFeature>();
+            Assert.Empty(addressesFeature.Addresses);
+            Assert.Empty(attachedServer.Listener.Options.UrlPrefixes);
+        }
+
         private async Task<string> SendRequestAsync(string uri)
         {
             using (HttpClient client = new HttpClient() { Timeout = Utilities.DefaultTimeout })