Add new Microsoft.AspNetCore.SpaServices.Extensions package to host new runtime functionality needed for updated templates until 2.1 ships

src/Microsoft.AspNetCore.SpaServices.Extensions/AngularCli/AngularCliMiddleware.cs

@@ -0,0 +1,131 @@
+// 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 Microsoft.AspNetCore.Builder;
+using System;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.NodeServices.Npm;
+using System.Text.RegularExpressions;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Console;
+using System.Net.Sockets;
+using System.Net;
+using System.IO;
+using Microsoft.AspNetCore.NodeServices.Util;
+
+namespace Microsoft.AspNetCore.SpaServices.AngularCli
+{
+    internal static class AngularCliMiddleware
+    {
+        private const string LogCategoryName = "Microsoft.AspNetCore.SpaServices";
+        private static TimeSpan RegexMatchTimeout = TimeSpan.FromSeconds(5); // This is a development-time only feature, so a very long timeout is fine
+        private static TimeSpan StartupTimeout = TimeSpan.FromSeconds(50); // Note that the HTTP request itself by default times out after 60s, so you only get useful error information if this is shorter
+
+        public static void Attach(
+            ISpaBuilder spaBuilder,
+            string npmScriptName)
+        {
+            var sourcePath = spaBuilder.Options.SourcePath;
+            if (string.IsNullOrEmpty(sourcePath))
+            {
+                throw new ArgumentException("Cannot be null or empty", nameof(sourcePath));
+            }
+
+            if (string.IsNullOrEmpty(npmScriptName))
+            {
+                throw new ArgumentException("Cannot be null or empty", nameof(npmScriptName));
+            }
+
+            // Start Angular CLI and attach to middleware pipeline
+            var appBuilder = spaBuilder.ApplicationBuilder;
+            var logger = GetOrCreateLogger(appBuilder);
+            var angularCliServerInfoTask = StartAngularCliServerAsync(sourcePath, npmScriptName, logger);
+
+            // Everything we proxy is hardcoded to target http://localhost because:
+            // - the requests are always from the local machine (we're not accepting remote
+            //   requests that go directly to the Angular CLI middleware server)
+            // - given that, there's no reason to use https, and we couldn't even if we
+            //   wanted to, because in general the Angular CLI server has no certificate
+            var targetUriTask = angularCliServerInfoTask.ContinueWith(
+                task => new UriBuilder("http", "localhost", task.Result.Port).Uri);
+
+            SpaProxyingExtensions.UseProxyToSpaDevelopmentServer(spaBuilder, targetUriTask);
+        }
+
+        internal static ILogger GetOrCreateLogger(IApplicationBuilder appBuilder)
+        {
+            // If the DI system gives us a logger, use it. Otherwise, set up a default one.
+            var loggerFactory = appBuilder.ApplicationServices.GetService<ILoggerFactory>();
+            var logger = loggerFactory != null
+                ? loggerFactory.CreateLogger(LogCategoryName)
+                : new ConsoleLogger(LogCategoryName, null, false);
+            return logger;
+        }
+
+        private static async Task<AngularCliServerInfo> StartAngularCliServerAsync(
+            string sourcePath, string npmScriptName, ILogger logger)
+        {
+            var portNumber = FindAvailablePort();
+            logger.LogInformation($"Starting @angular/cli on port {portNumber}...");
+
+            var npmScriptRunner = new NpmScriptRunner(
+                sourcePath, npmScriptName, $"--port {portNumber}");
+            npmScriptRunner.AttachToLogger(logger);
+
+            Match openBrowserLine;
+            using (var stdErrReader = new EventedStreamStringReader(npmScriptRunner.StdErr))
+            {
+                try
+                {
+                    openBrowserLine = await npmScriptRunner.StdOut.WaitForMatch(
+                        new Regex("open your browser on (http\\S+)", RegexOptions.None, RegexMatchTimeout),
+                        StartupTimeout);
+                }
+                catch (EndOfStreamException ex)
+                {
+                    throw new InvalidOperationException(
+                        $"The NPM script '{npmScriptName}' exited without indicating that the " +
+                        $"Angular CLI was listening for requests. The error output was: " +
+                        $"{stdErrReader.ReadAsString()}", ex);
+                }
+                catch (TaskCanceledException ex)
+                {
+                    throw new InvalidOperationException(
+                        $"The Angular CLI process did not start listening for requests " +
+                        $"within the timeout period of {StartupTimeout.Seconds} seconds. " +
+                        $"Check the log output for error information.", ex);
+                }
+            }
+
+            var uri = new Uri(openBrowserLine.Groups[1].Value);
+            var serverInfo = new AngularCliServerInfo { Port = uri.Port };
+
+            // Even after the Angular CLI claims to be listening for requests, there's a short
+            // period where it will give an error if you make a request too quickly. Give it
+            // a moment to finish starting up.
+            await Task.Delay(500);
+
+            return serverInfo;
+        }
+
+        private static int FindAvailablePort()
+        {
+            var listener = new TcpListener(IPAddress.Loopback, 0);
+            listener.Start();
+            try
+            {
+                return ((IPEndPoint)listener.LocalEndpoint).Port;
+            }
+            finally
+            {
+                listener.Stop();
+            }
+        }
+
+        class AngularCliServerInfo
+        {
+            public int Port { get; set; }
+        }
+    }
+}