Warn instead of throw when ignoring IServerAddressesFeature

KestrelHttpServer.sln

@@ -36,6 +36,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "shared", "shared", "{0EF2AC
 	ProjectSection(SolutionItems) = preProject
 		test\shared\DummyApplication.cs = test\shared\DummyApplication.cs
 		test\shared\HttpClientSlim.cs = test\shared\HttpClientSlim.cs
+		test\shared\KestrelTestLoggerFactory.cs = test\shared\KestrelTestLoggerFactory.cs
 		test\shared\LifetimeNotImplemented.cs = test\shared\LifetimeNotImplemented.cs
 		test\shared\MockConnection.cs = test\shared\MockConnection.cs
 		test\shared\MockFrameControl.cs = test\shared\MockFrameControl.cs

samples/SampleApp/Startup.cs

@@ -34,33 +34,34 @@ public void Configure(IApplicationBuilder app, ILoggerFactory loggerFactory)
 
         public static void Main(string[] args)
         {
-            var hostBuilder = new WebHostBuilder().UseKestrel(options =>
-            {
-                options.Listen(IPAddress.Loopback, 5000, listenOptions =>
+            var host = new WebHostBuilder()
+                .UseKestrel(options =>
                 {
-                    // Uncomment the following to enable Nagle's algorithm for this endpoint.
-                    //listenOptions.NoDelay = false;
+                    options.Listen(IPAddress.Loopback, 5000, listenOptions =>
+                    {
+                        // Uncomment the following to enable Nagle's algorithm for this endpoint.
+                        //listenOptions.NoDelay = false;
 
-                    listenOptions.UseConnectionLogging();
-                });
-                options.Listen(IPAddress.Loopback, 5001, listenOptions =>
-                {
-                    listenOptions.UseHttps("testCert.pfx", "testPassword");
-                    listenOptions.UseConnectionLogging();
-                });
+                        listenOptions.UseConnectionLogging();
+                    });
+                    options.Listen(IPAddress.Loopback, 5001, listenOptions =>
+                    {
+                        listenOptions.UseHttps("testCert.pfx", "testPassword");
+                        listenOptions.UseConnectionLogging();
+                    });
 
-                options.UseSystemd();
+                    options.UseSystemd();
 
-                // The following section should be used to demo sockets
-                //options.ListenUnixSocket("/tmp/kestrel-test.sock");
+                    // The following section should be used to demo sockets
+                    //options.ListenUnixSocket("/tmp/kestrel-test.sock");
 
-                // Uncomment the following line to change the default number of libuv threads for all endpoints.
-                //options.ThreadCount = 4;
-            })
-            .UseContentRoot(Directory.GetCurrentDirectory())
-            .UseStartup<Startup>();
+                    // Uncomment the following line to change the default number of libuv threads for all endpoints.
+                    //options.ThreadCount = 4;
+                })
+                .UseContentRoot(Directory.GetCurrentDirectory())
+                .UseStartup<Startup>()
+                .Build();
 
-            var host = hostBuilder.Build();
             host.Run();
         }
     }

src/Microsoft.AspNetCore.Server.Kestrel/Internal/Infrastructure/Constants.cs

@@ -1,19 +1,24 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Net;
 using System.Runtime.InteropServices;
-using System.Text;
 
 namespace Microsoft.AspNetCore.Server.Kestrel.Internal.Infrastructure
 {
-    internal class Constants
+    internal static class Constants
     {
         public const int ListenBacklog = 128;
 
         public const int EOF = -4095;
         public static readonly int? ECONNRESET = GetECONNRESET();
         public static readonly int? EADDRINUSE = GetEADDRINUSE();
 
+        /// <summary>
+        /// The IPEndPoint Kestrel will bind to if nothing else is specified.
+        /// </summary>
+        public static readonly IPEndPoint DefaultIPEndPoint = new IPEndPoint(IPAddress.Loopback, 5000);
+
         /// <summary>
         /// Prefix of host name used to specify Unix sockets in the configuration.
         /// </summary>

src/Microsoft.AspNetCore.Server.Kestrel/KestrelServer.cs

@@ -112,22 +112,24 @@ public void Start<TContext>(IHttpApplication<TContext> application)
                 }
 
                 engine.Start(threadCount);
-                var atLeastOneListener = false;
 
                 var listenOptions = Options.ListenOptions;
+                var hasListenOptions = listenOptions.Any();
+                var hasServerAddresses = _serverAddresses.Addresses.Any();
 
-                if (listenOptions.Any())
+                if (hasListenOptions && hasServerAddresses)
                 {
-                    var addresses = _serverAddresses.Addresses;
-                    if (addresses.SingleOrDefault() != "http://localhost:5000")
-                    {
-                        var joined = string.Join(", ", addresses);
-                        throw new NotSupportedException($"Specifying address(es) '{joined}' is incompatible with also configuring endpoint(s) in UseKestrel.");
-                    }
+                    var joined = string.Join(", ", _serverAddresses.Addresses);
+                    _logger.LogWarning($"Overriding address(es) '{joined}'. Binding to endpoints defined in {nameof(WebHostBuilderKestrelExtensions.UseKestrel)}() instead.");
 
                     _serverAddresses.Addresses.Clear();
                 }
-                else
+                else if (!hasListenOptions && !hasServerAddresses)
+                {
+                    _logger.LogDebug($"No listening endpoints were configured. Binding to {Constants.DefaultIPEndPoint} by default.");
+                    listenOptions.Add(new ListenOptions(Constants.DefaultIPEndPoint));
+                }
+                else if (!hasListenOptions)
                 {
                     // If no endpoints are configured directly using KestrelServerOptions, use those configured via the IServerAddressesFeature.
                     var copiedAddresses = _serverAddresses.Addresses.ToArray();
@@ -155,7 +157,6 @@ public void Start<TContext>(IHttpApplication<TContext> application)
                                 // If StartLocalhost doesn't throw, there is at least one listener.
                                 // The port cannot change for "localhost".
                                 _serverAddresses.Addresses.Add(parsedAddress.ToString());
-                                atLeastOneListener = true;
                             }
                             else
                             {
@@ -172,8 +173,6 @@ public void Start<TContext>(IHttpApplication<TContext> application)
 
                 foreach (var endPoint in listenOptions)
                 {
-                    atLeastOneListener = true;
-
                     try
                     {
                         _disposables.Push(engine.CreateServer(endPoint));
@@ -191,11 +190,6 @@ public void Start<TContext>(IHttpApplication<TContext> application)
                     // If requested port was "0", replace with assigned dynamic port.
                     _serverAddresses.Addresses.Add(endPoint.ToString());
                 }
-
-                if (!atLeastOneListener)
-                {
-                    throw new InvalidOperationException("No recognized listening addresses were configured.");
-                }
             }
             catch (Exception ex)
             {

test/Microsoft.AspNetCore.Server.Kestrel.FunctionalTests/AddressRegistrationTests.cs

@@ -16,6 +16,8 @@
 using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.AspNetCore.Testing;
 using Microsoft.AspNetCore.Testing.xunit;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Xunit;
 
@@ -126,6 +128,35 @@ private async Task RegisterIPEndPoint_Success(IPEndPoint endPoint, Func<IPEndPoi
             }
         }
 
+        [ConditionalFact(Skip = "Waiting on https://github.com/aspnet/Hosting/issues/917")]
+        [PortSupportedCondition(5000)]
+        public async Task DefaultsToPort5000()
+        {
+            var testLogger = new TestApplicationErrorLogger();
+
+            var hostBuilder = new WebHostBuilder()
+               .UseKestrel()
+               .ConfigureServices(services =>
+                {
+                    services.AddSingleton<ILoggerFactory>(new KestrelTestLoggerFactory(testLogger));
+                })
+               .Configure(ConfigureEchoAddress);
+
+            using (var host = hostBuilder.Build())
+            {
+                host.Start();
+
+                var debugLog = testLogger.Messages.Single(log => log.LogLevel == LogLevel.Debug);
+                Assert.True(debugLog.Message.Contains("default"));
+
+                foreach (var testUrl in new[] { "http://127.0.0.1:5000", "http://localhost:5000" })
+                {
+                    var response = await HttpClientSlim.GetStringAsync(testUrl);
+                    Assert.Equal(new Uri(testUrl).ToString(), response);
+                }
+            }
+        }
+
         [Fact]
         public void ThrowsWhenBindingToIPv4AddressInUse()
         {

test/Microsoft.AspNetCore.Server.KestrelTests/KestrelServerTests.cs

@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Linq;
+using System.Net;
 using Microsoft.AspNetCore.Hosting.Server;
 using Microsoft.AspNetCore.Hosting.Server.Features;
 using Microsoft.AspNetCore.Server.Kestrel;
@@ -43,16 +45,26 @@ public void StartWithInvalidAddressThrows()
             Assert.Equal(1, testLogger.CriticalErrorsLogged);
         }
 
-        [Fact]
-        public void StartWithEmptyAddressesThrows()
+        [Theory]
+        [InlineData("http://localhost:5000")]
+        [InlineData("The value of the string shouldn't matter.")]
+        [InlineData(null)]
+        public void StartWarnsWhenIgnoringIServerAddressesFeature(string ignoredAddress)
         {
             var testLogger = new TestApplicationErrorLogger();
-            var server = CreateServer(new KestrelServerOptions(), testLogger);
+            var kestrelOptions = new KestrelServerOptions();
 
-            var exception = Assert.Throws<InvalidOperationException>(() => StartDummyApplication(server));
+            // Directly configuring an endpoint using Listen causes the IServerAddressesFeature to be ignored.
+            kestrelOptions.Listen(IPAddress.Loopback, 0);
 
-            Assert.Equal("No recognized listening addresses were configured.", exception.Message);
-            Assert.Equal(1, testLogger.CriticalErrorsLogged);
+            using (var server = CreateServer(kestrelOptions, testLogger))
+            {
+                server.Features.Get<IServerAddressesFeature>().Addresses.Add(ignoredAddress);
+                StartDummyApplication(server);
+
+                var warning = testLogger.Messages.Single(log => log.LogLevel == LogLevel.Warning);
+                Assert.True(warning.Message.Contains("Overriding"));
+            }
         }
 
         [Theory]
@@ -87,37 +99,12 @@ private static KestrelServer CreateServer(KestrelServerOptions options, ILogger
         {
             var lifetime = new LifetimeNotImplemented();
 
-            return new KestrelServer(Options.Create(options), lifetime, new TestLoggerFactory(testLogger));
+            return new KestrelServer(Options.Create(options), lifetime, new KestrelTestLoggerFactory(testLogger));
         }
 
         private static void StartDummyApplication(IServer server)
         {
             server.Start(new DummyApplication(context => TaskCache.CompletedTask));
         }
-
-        private class TestLoggerFactory : ILoggerFactory
-        {
-            private readonly ILogger _testLogger;
-
-            public TestLoggerFactory(ILogger testLogger)
-            {
-                _testLogger = testLogger;
-            }
-
-            public ILogger CreateLogger(string categoryName)
-            {
-                return _testLogger;
-            }
-
-            public void AddProvider(ILoggerProvider provider)
-            {
-                throw new NotImplementedException();
-            }
-
-            public void Dispose()
-            {
-                throw new NotImplementedException();
-            }
-        }
     }
 }

test/shared/KestrelTestLoggerFactory.cs

@@ -0,0 +1,33 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Testing
+{
+    public class KestrelTestLoggerFactory : ILoggerFactory
+    {
+        private readonly ILogger _testLogger;
+
+        public KestrelTestLoggerFactory(ILogger testLogger)
+        {
+            _testLogger = testLogger;
+        }
+
+        public ILogger CreateLogger(string categoryName)
+        {
+            return _testLogger;
+        }
+
+        public void AddProvider(ILoggerProvider provider)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void Dispose()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

test/shared/TestApplicationErrorLogger.cs

@@ -38,14 +38,21 @@ public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Except
             Console.WriteLine($"Log {logLevel}[{eventId}]: {formatter(state, exception)} {exception?.Message}");
 #endif
 
-            Messages.Add(new LogMessage { LogLevel = logLevel, EventId = eventId, Exception = exception });
+            Messages.Add(new LogMessage
+            {
+                LogLevel = logLevel,
+                EventId = eventId,
+                Exception = exception,
+                Message = formatter(state, exception)
+            });
         }
 
         public class LogMessage
         {
             public LogLevel LogLevel { get; set; }
             public EventId EventId { get; set; }
             public Exception Exception { get; set; }
+            public string Message { get; set; }
         }
     }
 }