Added OnBeforeStartExternalProcess callback which to NodeServicesOptions (and OutOfProcessNodeInstance, SocketNodeInstance and HttpNodeInstance) to configure environment of the node.exe process to be started, and the path to the node executable itself. Fixes #20

Author: thunder7553

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

@@ -14,7 +14,7 @@ public NodeServicesOptions()
             HostingModel = DefaultNodeHostingModel;
             WatchFileExtensions = (string[])DefaultWatchFileExtensions.Clone();
         }
-
+        public Action<System.Diagnostics.ProcessStartInfo> OnBeforeStartExternalProcess { get; set; }
         public NodeHostingModel HostingModel { get; set; }
         public Func<INodeInstance> NodeInstanceFactory { get; set; }
         public string ProjectPath { get; set; }

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

@@ -28,21 +28,22 @@ internal class HttpNodeInstance : OutOfProcessNodeInstance
             ContractResolver = new CamelCasePropertyNamesContractResolver()
         };
 
-	    private readonly HttpClient _client;
+        private readonly HttpClient _client;
         private bool _disposed;
         private int _portNumber;
 
-        public HttpNodeInstance(string projectPath, string[] watchFileExtensions, int port = 0)
+        public HttpNodeInstance(string projectPath, string[] watchFileExtensions, int port = 0, Action<System.Diagnostics.ProcessStartInfo> onBeforeStartExternalProcess = null)
             : base(
                 EmbeddedResourceReader.Read(
                     typeof(HttpNodeInstance),
                     "/Content/Node/entrypoint-http.js"),
                 projectPath,
                 watchFileExtensions,
-                MakeCommandLineOptions(port))
+                MakeCommandLineOptions(port),
+                onBeforeStartExternalProcess)
         {
             _client = new HttpClient();
-		}
+        }
 
         private static string MakeCommandLineOptions(int port)
         {
@@ -112,18 +113,19 @@ protected override void OnOutputDataReceived(string outputData)
             }
         }
 
-	    protected override void Dispose(bool disposing) {
-	        base.Dispose(disposing);
+        protected override void Dispose(bool disposing)
+        {
+            base.Dispose(disposing);
 
-	        if (!_disposed)
+            if (!_disposed)
             {
-	            if (disposing)
+                if (disposing)
                 {
-	                _client.Dispose();
-	            }
+                    _client.Dispose();
+                }
 
-	            _disposed = true;
-	        }
-	    }
-	}
+                _disposed = true;
+            }
+        }
+    }
 }

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

@@ -31,10 +31,11 @@ public OutOfProcessNodeInstance(
             string entryPointScript,
             string projectPath,
             string[] watchFileExtensions,
-            string commandLineArguments)
+            string commandLineArguments,
+             Action<System.Diagnostics.ProcessStartInfo> onBeforeStartExternalProcess = null)
         {
             _entryPointScript = new StringAsTempFile(entryPointScript);
-            _nodeProcess = LaunchNodeProcess(_entryPointScript.FileName, projectPath, commandLineArguments);
+            _nodeProcess = LaunchNodeProcess(_entryPointScript.FileName, projectPath, commandLineArguments, onBeforeStartExternalProcess);
             _watchFileExtensions = watchFileExtensions;
             _fileSystemWatcher = BeginFileWatcher(projectPath);
             ConnectToInputOutputStreams();
@@ -111,7 +112,7 @@ private void EnsureFileSystemWatcherIsDisposed()
             }
         }
 
-        private static Process LaunchNodeProcess(string entryPointFilename, string projectPath, string commandLineArguments)
+        private static Process LaunchNodeProcess(string entryPointFilename, string projectPath, string commandLineArguments, Action<System.Diagnostics.ProcessStartInfo> onBeforeStartExternalProcess)
         {
             var startInfo = new ProcessStartInfo("node")
             {
@@ -136,6 +137,10 @@ private static Process LaunchNodeProcess(string entryPointFilename, string proje
 #else
             startInfo.Environment["NODE_PATH"] = nodePathValue;
 #endif
+            if (onBeforeStartExternalProcess != null)
+            {
+                onBeforeStartExternalProcess(startInfo);
+            }
 
             var process = Process.Start(startInfo);
 

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

@@ -25,7 +25,7 @@ namespace Microsoft.AspNetCore.NodeServices.HostingModels
     /// <seealso cref="Microsoft.AspNetCore.NodeServices.HostingModels.OutOfProcessNodeInstance" />
     internal class SocketNodeInstance : OutOfProcessNodeInstance
     {
-        private readonly static JsonSerializerSettings jsonSerializerSettings =  new JsonSerializerSettings
+        private readonly static JsonSerializerSettings jsonSerializerSettings = new JsonSerializerSettings
         {
             ContractResolver = new CamelCasePropertyNamesContractResolver()
         };
@@ -36,16 +36,17 @@ internal class SocketNodeInstance : OutOfProcessNodeInstance
         private string _socketAddress;
         private VirtualConnectionClient _virtualConnectionClient;
 
-        public SocketNodeInstance(string projectPath, string[] watchFileExtensions, string socketAddress): base(
+        public SocketNodeInstance(string projectPath, string[] watchFileExtensions, string socketAddress, Action<System.Diagnostics.ProcessStartInfo> onBeforeStartExternalProcess = null) : base(
                 EmbeddedResourceReader.Read(
                     typeof(SocketNodeInstance),
                     "/Content/Node/entrypoint-socket.js"),
                 projectPath,
                 watchFileExtensions,
-                MakeNewCommandLineOptions(socketAddress))
+                MakeNewCommandLineOptions(socketAddress),
+                onBeforeStartExternalProcess)
         {
             _socketAddress = socketAddress;
-		}
+        }
 
         protected override async Task<T> InvokeExportAsync<T>(NodeInvocationInfo invocationInfo)
         {
@@ -170,7 +171,7 @@ private static async Task<T> ReadJsonAsync<T>(Stream stream)
 
         private static async Task<byte[]> ReadAllBytesAsync(Stream input)
         {
-            byte[] buffer = new byte[16*1024];
+            byte[] buffer = new byte[16 * 1024];
 
             using (var ms = new MemoryStream())
             {