Add ability to configure environment variables for Node instances, plus auto-populate NODE_ENV based on IHostingEnvironment when possible. Fixes #230

src/Microsoft.AspNetCore.NodeServices/Configuration/Configuration.cs

@@ -20,12 +20,15 @@ namespace Microsoft.AspNetCore.NodeServices
             {
                 // Since this instance is being created through DI, we can access the IHostingEnvironment
                 // to populate options.ProjectPath if it wasn't explicitly specified.                
+                var hostEnv = serviceProvider.GetRequiredService<IHostingEnvironment>();
                 if (string.IsNullOrEmpty(options.ProjectPath))
                 {
-                    var hostEnv = serviceProvider.GetRequiredService<IHostingEnvironment>();
                     options.ProjectPath = hostEnv.ContentRootPath;
                 }
 
+                // Similarly, we can determine the 'is development' value from the hosting environment
+                options.AddDefaultEnvironmentVariables(hostEnv.IsDevelopment());
+
                 // Likewise, if no logger was specified explicitly, we should use the one from DI.
                 // If it doesn't provide one, CreateNodeInstance will set up a default.
                 if (options.NodeInstanceOutputLogger == null)
@@ -69,11 +72,11 @@ namespace Microsoft.AspNetCore.NodeServices
                 {
                     case NodeHostingModel.Http:
                         return new HttpNodeInstance(options.ProjectPath, options.WatchFileExtensions, logger, 
-                            options.LaunchWithDebugging, options.DebuggingPort, /* port */ 0);
+                            options.EnvironmentVariables, options.LaunchWithDebugging, options.DebuggingPort, /* port */ 0);
                     case NodeHostingModel.Socket:
                         var pipeName = "pni-" + Guid.NewGuid().ToString("D"); // Arbitrary non-clashing string
                         return new SocketNodeInstance(options.ProjectPath, options.WatchFileExtensions, pipeName, logger,
-                            options.LaunchWithDebugging, options.DebuggingPort);
+                            options.EnvironmentVariables, options.LaunchWithDebugging, options.DebuggingPort);
                     default:
                         throw new ArgumentException("Unknown hosting model: " + options.HostingModel);
                 }

src/Microsoft.AspNetCore.NodeServices/Configuration/NodeServicesOptions.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using Microsoft.AspNetCore.NodeServices.HostingModels;
 using Microsoft.Extensions.Logging;
 
@@ -22,6 +23,23 @@ namespace Microsoft.AspNetCore.NodeServices
         public string[] WatchFileExtensions { get; set; }
         public ILogger NodeInstanceOutputLogger { get; set; }
         public bool LaunchWithDebugging { get; set; }
+        public IDictionary<string, string> EnvironmentVariables { get; set; }
         public int? DebuggingPort { get; set; }
+
+        public NodeServicesOptions AddDefaultEnvironmentVariables(bool isDevelopmentMode)
+        {
+            if (EnvironmentVariables == null)
+            {
+                EnvironmentVariables = new Dictionary<string, string>();
+            }
+
+            if (!EnvironmentVariables.ContainsKey("NODE_ENV"))
+            {
+                // These strings are a de-facto standard in Node
+                EnvironmentVariables["NODE_ENV"] = isDevelopmentMode ? "development" : "production";
+            }
+
+            return this;
+        }
     }
 }

src/Microsoft.AspNetCore.NodeServices/HostingModels/HttpNodeInstance.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Net.Http;
 using System.Text;
@@ -34,7 +35,7 @@ namespace Microsoft.AspNetCore.NodeServices.HostingModels
         private int _portNumber;
 
         public HttpNodeInstance(string projectPath, string[] watchFileExtensions, ILogger nodeInstanceOutputLogger,
-            bool launchWithDebugging, int? debuggingPort, int port = 0)
+            IDictionary<string, string> environmentVars, bool launchWithDebugging, int? debuggingPort, int port = 0)
         : base(
                 EmbeddedResourceReader.Read(
                     typeof(HttpNodeInstance),
@@ -43,6 +44,7 @@ namespace Microsoft.AspNetCore.NodeServices.HostingModels
                 watchFileExtensions,
                 MakeCommandLineOptions(port),
                 nodeInstanceOutputLogger,
+                environmentVars,
                 launchWithDebugging,
                 debuggingPort)
         {

src/Microsoft.AspNetCore.NodeServices/HostingModels/OutOfProcessNodeInstance.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
@@ -46,6 +47,7 @@ If you haven't yet installed node-inspector, you can do so as follows:
             string[] watchFileExtensions,
             string commandLineArguments,
             ILogger nodeOutputLogger,
+            IDictionary<string, string> environmentVars,
             bool launchWithDebugging,
             int? debuggingPort)
         {
@@ -58,7 +60,7 @@ If you haven't yet installed node-inspector, you can do so as follows:
             _entryPointScript = new StringAsTempFile(entryPointScript);
 
             var startInfo = PrepareNodeProcessStartInfo(_entryPointScript.FileName, projectPath, commandLineArguments,
-                launchWithDebugging, debuggingPort);
+                environmentVars, launchWithDebugging, debuggingPort);
             _nodeProcess = LaunchNodeProcess(startInfo);
             _watchFileExtensions = watchFileExtensions;
             _fileSystemWatcher = BeginFileWatcher(projectPath);
@@ -99,7 +101,7 @@ If you haven't yet installed node-inspector, you can do so as follows:
         // This method is virtual, as it provides a way to override the NODE_PATH or the path to node.exe
         protected virtual ProcessStartInfo PrepareNodeProcessStartInfo(
             string entryPointFilename, string projectPath, string commandLineArguments,
-            bool launchWithDebugging, int? debuggingPort)
+            IDictionary<string, string> environmentVars, bool launchWithDebugging, int? debuggingPort)
         {
             string debuggingArgs;
             if (launchWithDebugging)
@@ -122,6 +124,19 @@ If you haven't yet installed node-inspector, you can do so as follows:
                 WorkingDirectory = projectPath
             };
 
+            // Append environment vars
+            if (environmentVars != null)
+            {
+                foreach (var envVarKey in environmentVars.Keys)
+                {
+                    var envVarValue = environmentVars[envVarKey];
+                    if (envVarValue != null)
+                    {
+                        SetEnvironmentVariable(startInfo, envVarKey, envVarValue);
+                    }
+                }
+            }
+
             // Append projectPath to NODE_PATH so it can locate node_modules
             var existingNodePath = Environment.GetEnvironmentVariable("NODE_PATH") ?? string.Empty;
             if (existingNodePath != string.Empty)
@@ -130,11 +145,7 @@ If you haven't yet installed node-inspector, you can do so as follows:
             }
 
             var nodePathValue = existingNodePath + Path.Combine(projectPath, "node_modules");
-#if NET451
+            SetEnvironmentVariable(startInfo, "NODE_PATH", nodePathValue);
-            startInfo.EnvironmentVariables["NODE_PATH"] = nodePathValue;
-#else
-            startInfo.Environment["NODE_PATH"] = nodePathValue;
-#endif
 
             return startInfo;
         }
@@ -179,6 +190,15 @@ If you haven't yet installed node-inspector, you can do so as follows:
             }
         }
 
+        private static void SetEnvironmentVariable(ProcessStartInfo startInfo, string name, string value)
+        {
+#if NET451
+            startInfo.EnvironmentVariables[name] = value;
+#else
+            startInfo.Environment[name] = value;
+#endif
+        }
+
         private static Process LaunchNodeProcess(ProcessStartInfo startInfo)
         {
             var process = Process.Start(startInfo);

src/Microsoft.AspNetCore.NodeServices/HostingModels/SocketNodeInstance.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Text;
 using System.Threading;
@@ -38,7 +39,8 @@ namespace Microsoft.AspNetCore.NodeServices.HostingModels
         private VirtualConnectionClient _virtualConnectionClient;
 
         public SocketNodeInstance(string projectPath, string[] watchFileExtensions, string socketAddress,
-            ILogger nodeInstanceOutputLogger, bool launchWithDebugging, int? debuggingPort)
+            ILogger nodeInstanceOutputLogger, IDictionary<string, string> environmentVars,
+            bool launchWithDebugging, int? debuggingPort)
         : base(
                 EmbeddedResourceReader.Read(
                     typeof(SocketNodeInstance),
@@ -47,6 +49,7 @@ namespace Microsoft.AspNetCore.NodeServices.HostingModels
                 watchFileExtensions,
                 MakeNewCommandLineOptions(socketAddress),
                 nodeInstanceOutputLogger,
+                environmentVars,
                 launchWithDebugging,
                 debuggingPort)
         {

src/Microsoft.AspNetCore.SpaServices/Prerendering/PrerenderTagHelper.cs

@@ -36,7 +36,7 @@ namespace Microsoft.AspNetCore.SpaServices.Prerendering
                 _nodeServices = _fallbackNodeServices = Configuration.CreateNodeServices(new NodeServicesOptions
                 {
                     ProjectPath = _applicationBasePath
-                });
+                }.AddDefaultEnvironmentVariables(hostEnv.IsDevelopment()));
             }
         }
 

src/Microsoft.AspNetCore.SpaServices/Webpack/WebpackDevMiddleware.cs

@@ -35,16 +35,8 @@ namespace Microsoft.AspNetCore.Builder
                     "To enable ReactHotModuleReplacement, you must also enable HotModuleReplacement.");
             }
 
-            string projectPath;
+            var hostEnv = (IHostingEnvironment)appBuilder.ApplicationServices.GetService(typeof(IHostingEnvironment));
-            if (options.ProjectPath == null)
+            var projectPath = options.ProjectPath ?? hostEnv.ContentRootPath;
-            {
-                var hostEnv = (IHostingEnvironment)appBuilder.ApplicationServices.GetService(typeof(IHostingEnvironment));
-                projectPath = hostEnv.ContentRootPath;
-            }
-            else
-            {
-                projectPath = options.ProjectPath;
-            }
 
             // Unlike other consumers of NodeServices, WebpackDevMiddleware dosen't share Node instances, nor does it
             // use your DI configuration. It's important for WebpackDevMiddleware to have its own private Node instance
@@ -55,7 +47,7 @@ namespace Microsoft.AspNetCore.Builder
             {
                 ProjectPath = projectPath,
                 WatchFileExtensions = new string[] { } // Don't watch anything
-            });
+            }.AddDefaultEnvironmentVariables(hostEnv.IsDevelopment()));
 
             // Get a filename matching the middleware Node script
             var script = EmbeddedResourceReader.Read(typeof(WebpackDevMiddleware),