Add Fastboot server

Author: kzys

fastboot.js

@@ -0,0 +1,63 @@
+/* eslint-disable no-console */
+/* eslint-env node */
+
+'use strict';
+
+const fs = require('fs');
+const os = require('os');
+const FastBootAppServer = require('fastboot-app-server');
+
+// because fastboot-app-server uses cluster, but it might change in future
+const cluster = require('cluster');
+
+class LoggerWithoutTimestamp {
+  constructor() {
+    this.prefix = cluster.isMaster ? 'master' : 'worker';
+  }
+  writeLine() {
+    this._write('info', Array.prototype.slice.apply(arguments));
+  }
+
+  writeError() {
+    this._write('error', Array.prototype.slice.apply(arguments));
+  }
+
+  _write(level, args) {
+    args[0] = `[${level}][${this.prefix}] ${args[0]}`;
+    console.log.apply(console, args);
+  }
+}
+
+function writeAppInitializedWhenReady(logger) {
+  let timeout;
+
+  timeout = setInterval(function() {
+    logger.writeLine('waiting backend');
+    if (fs.existsSync('/tmp/backend-initialized')) {
+      logger.writeLine('backend is up. let heroku know the app is ready');
+      fs.writeFileSync('/tmp/app-initialized', 'hello');
+      clearInterval(timeout);
+    } else {
+      logger.writeLine('backend is still not up');
+    }
+  }, 1000);
+}
+
+var logger = new LoggerWithoutTimestamp();
+
+logger.writeLine(`${os.cpus().length} cores available`);
+
+let workerCount = process.env.WEB_CONCURRENCY || 1;
+
+let server = new FastBootAppServer({
+  distPath: 'dist',
+  port: 9000,
+  ui: logger,
+  workerCount: workerCount,
+});
+
+if (!cluster.isWorker) {
+  writeAppInitializedWhenReady(logger);
+}
+
+server.start();