electron: patch process.versions.electron

When forking, Electron 4 forgets to set `process.versions.electron` in
the sub-process, making some packages wrongly guess their environment.

This commit manually patches this variable.

Signed-off-by: Paul Maréchal <paul.marechal@ericsson.com>

dev-packages/application-manager/src/generator/backend-generator.ts

@@ -27,6 +27,12 @@ export class BackendGenerator extends AbstractGenerator {
     protected compileServer(backendModules: Map<string, string>): string {
         return `// @ts-check
 require('reflect-metadata');
+
+// Patch electron version if missing, see https://github.com/eclipse-theia/theia/pull/7361#pullrequestreview-377065146
+if (typeof process.versions.electron === 'undefined' && typeof process.env.THEIA_ELECTRON_VERSION === 'string') {
+    process.versions.electron = process.env.THEIA_ELECTRON_VERSION;
+}
+
 const path = require('path');
 const express = require('express');
 const { Container } = require('inversify');

dev-packages/application-manager/src/generator/frontend-generator.ts

@@ -327,16 +327,13 @@ app.on('ready', () => {
 
     // Set the electron version for both the dev and the production mode. (https://github.com/eclipse-theia/theia/issues/3254)
     // Otherwise, the forked backend processes will not know that they're serving the electron frontend.
-    const { versions } = process;
-    // @ts-ignore
-    if (versions && typeof versions.electron !== 'undefined') {
-        // @ts-ignore
-        process.env.THEIA_ELECTRON_VERSION = versions.electron;
-    }
+    // The forked backend should patch its \`process.versions.electron\` with this value if it is missing.
+    process.env.THEIA_ELECTRON_VERSION = process.versions.electron;
 
     const mainPath = join(__dirname, '..', 'backend', 'main');
-    // We need to distinguish between bundled application and development mode when starting the clusters.
-    // See: https://github.com/electron/electron/issues/6337#issuecomment-230183287
+    // We spawn a separate process for the backend for Express to not run in the Electron main process.
+    // See: https://github.com/eclipse-theia/theia/pull/7361#issuecomment-601272212
+    // But when in development mode, we will not spawn a new process, to ease with debugging (devMode).
     if (devMode) {
         process.env[ElectronSecurityToken] = JSON.stringify(electronSecurityToken);
         require(mainPath).then(address => {

dev-packages/application-package/src/environment.ts

@@ -29,12 +29,10 @@ class ElectronEnv {
     /**
      * `true` if running in electron. Otherwise, `false`.
      *
-     * Can be called from both the `main` and the render process. Also works for forked cluster workers.
+     * Can be called from both the `main` and the render process.
      */
     is(): boolean {
-        // When forking a new process from the cluster, we can rely neither on `process.versions` nor `process.argv`.
-        // Se we look into the `process.env` as well. `is-electron` does not do it for us.
-        return isElectron() || typeof process !== 'undefined' && typeof process.env === 'object' && !!process.env.THEIA_ELECTRON_VERSION;
+        return isElectron();
     }
 
     /**