Start FlipperServerImpl as part of flipper-server

Summary: The previous started up a dev / web server for bundling in flipper-server, this diff starts the flipper server itself, so that we can connect the client to it (done in next diffs)

Reviewed By: passy, aigoncharov

Differential Revision: D32627390

fbshipit-source-id: b48de20f076e1e13842368d16a090708d533b69e

desktop/flipper-server/src/startBaseServer.tsx

@@ -0,0 +1,95 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import chalk from 'chalk';
+import express, {Express} from 'express';
+import http from 'http';
+import path from 'path';
+import fs from 'fs-extra';
+import socketio from 'socket.io';
+import {hostname} from 'os';
+
+type Config = {
+  port: number;
+  staticDir: string;
+  entry: string;
+};
+
+export async function startBaseServer(config: Config): Promise<{
+  app: Express;
+  server: http.Server;
+  socket: socketio.Server;
+}> {
+  checkDevServer();
+  const {app, server} = await startAssetServer(config);
+  const socket = addWebsocket(server);
+  return {
+    app,
+    server,
+    socket,
+  };
+}
+
+function startAssetServer(
+  config: Config,
+): Promise<{app: Express; server: http.Server}> {
+  const app = express();
+
+  app.use((_req, res, next) => {
+    res.header('Cache-Control', 'private, no-cache, no-store, must-revalidate');
+    res.header('Expires', '-1');
+    res.header('Pragma', 'no-cache');
+    next();
+  });
+
+  app.get('/', (_req, res) => {
+    fs.readFile(path.join(config.staticDir, config.entry), (_err, content) => {
+      res.end(content);
+    });
+  });
+
+  app.use(express.static(config.staticDir));
+
+  const server = http.createServer(app);
+
+  return new Promise((resolve) => {
+    server.listen(config.port, 'localhost', () => resolve({app, server}));
+  });
+}
+
+function addWebsocket(server: http.Server) {
+  const io = new socketio.Server(server); // 3.1.0 socket.io doesn't have type definitions
+
+  io.on('connection', (client) => {
+    console.log(chalk.green(`Client connected ${client.id}`));
+  });
+
+  return io;
+}
+
+function looksLikeDevServer(): boolean {
+  const hn = hostname();
+  if (/^devvm.*\.facebook\.com$/.test(hn)) {
+    return true;
+  }
+  if (hn.endsWith('.od.fbinfra.net')) {
+    return true;
+  }
+  return false;
+}
+
+function checkDevServer() {
+  if (looksLikeDevServer()) {
+    console.log(
+      chalk.red(
+        `✖ It looks like you're trying to start Flipper on your OnDemand or DevServer, which is not supported. Please run this in a local checkout on your laptop or desktop instead.`,
+      ),
+    );
+  }
+}