electron app - auto find port

app/package.json

@@ -25,9 +25,10 @@
   "homepage": "./",
   "scripts": {
     "start": "cross-env ELECTRON_START_URL=http://localhost:5000 electron .",
+    "start:local": "cross-env electron .",
     "dist": "electron-builder",
     "build": "cd ../packages/api && yarn build && cd ../web && yarn build:app && cd ../../app && yarn dist",
-    "wait-electron": "node src/electron-wait-react",
+    "build:local": "cd ../packages/api && yarn build && cd ../web && yarn build:app && cd ../../app && yarn predist",
     "postinstall": "electron-builder install-app-deps",
     "predist": "copyfiles ../packages/api/dist/* packages && copyfiles \"../packages/web/build/*\" packages && copyfiles \"../packages/web/build/**/*\" packages"
   },

app/src/electron-wait-react.js

@@ -1,27 +0,0 @@
-const net = require('net');
-const port = 5000;
-
-process.env.ELECTRON_START_URL = `http://localhost:${port}`;
-
-const client = new net.Socket();
-
-let startedElectron = false;
-const tryConnection = () => client.connect({port: port}, () => {
-        client.end();
-        if(!startedElectron) {
-            console.log('starting electron');
-            startedElectron = true;
-            const exec = require('child_process').exec;
-            const electron = exec('yarn electron');
-            electron.stdout.on("data", function(data) {
-                console.log("stdout: " + data.toString());
-            });
-        }
-    }
-);
-
-tryConnection();
-
-client.on('error', (error) => {
-    setTimeout(tryConnection, 1000);
-});

app/src/electron.js

@@ -14,18 +14,37 @@ let mainWindow;
 
 function createWindow() {
   // Create the browser window.
-  mainWindow = new BrowserWindow({ width: 800, height: 600 });
+  mainWindow = new BrowserWindow({
+    width: 800,
+    height: 600,
+    webPreferences: {
+      nodeIntegration: true,
+    },
+  });
 
-  const apiProcess = fork(path.join(__dirname, '../packages/api/dist/bundle.js'));
+  function loadMainWindow() {
+    const startUrl =
+      process.env.ELECTRON_START_URL ||
+      url.format({
+        pathname: path.join(__dirname, '../packages/web/build/index.html'),
+        protocol: 'file:',
+        slashes: true,
+      });
+    mainWindow.loadURL(startUrl);
+  }
 
-  const startUrl =
-    process.env.ELECTRON_START_URL ||
-    url.format({
-      pathname: path.join(__dirname, '../packages/web/build/index.html'),
-      protocol: 'file:',
-      slashes: true,
+  if (process.env.ELECTRON_START_URL) {
+    loadMainWindow();
+  } else {
+    const apiProcess = fork(path.join(__dirname, '../packages/api/dist/bundle.js'), ['--dynport']);
+    apiProcess.on('message', (msg) => {
+      if (msg.msgtype == 'listening') {
+        const { port } = msg;
+        global['port'] = port;
+        loadMainWindow();
+      }
     });
-  mainWindow.loadURL(startUrl);
+  }
 
   // and load the index.html of the app.
   // mainWindow.loadURL('http://localhost:3000');
@@ -34,7 +53,7 @@ function createWindow() {
   // mainWindow.webContents.openDevTools();
 
   // Emitted when the window is closed.
-  mainWindow.on('closed', function() {
+  mainWindow.on('closed', function () {
     // Dereference the window object, usually you would store windows
     // in an array if your app supports multi windows, this is the time
     // when you should delete the corresponding element.
@@ -48,7 +67,7 @@ function createWindow() {
 app.on('ready', createWindow);
 
 // Quit when all windows are closed.
-app.on('window-all-closed', function() {
+app.on('window-all-closed', function () {
   // On OS X it is common for applications and their menu bar
   // to stay active until the user quits explicitly with Cmd + Q
   if (process.platform !== 'darwin') {
@@ -56,7 +75,7 @@ app.on('window-all-closed', function() {
   }
 });
 
-app.on('activate', function() {
+app.on('activate', function () {
   // On OS X it's common to re-create a window in the app when the
   // dock icon is clicked and there are no other windows open.
   if (mainWindow === null) {