build: properly close firebase apps (#4743)

* Properly close the Firebase app connections to avoid that the NodeJS process keeps hanging.

tools/gulp/tasks/coverage.ts

@@ -3,7 +3,7 @@ import {existsSync} from 'fs-extra';
 import {COVERAGE_RESULT_FILE} from '../constants';
 import {spawnSync} from 'child_process';
 import {isTravisMasterBuild} from '../util/travis-ci';
-import {openFirebaseDashboardDatabase} from '../util/firebase';
+import {openFirebaseDashboardApp} from '../util/firebase';
 
 task('coverage:upload', () => {
   if (!existsSync(COVERAGE_RESULT_FILE)) {
@@ -24,11 +24,13 @@ task('coverage:upload', () => {
 
 /** Uploads the coverage results to the firebase database. */
 function uploadResults(results: any): Promise<void> {
-  let latestSha = spawnSync('git', ['rev-parse', 'HEAD']).stdout.toString().trim();
-  let database = openFirebaseDashboardDatabase();
+  const latestSha = spawnSync('git', ['rev-parse', 'HEAD']).stdout.toString().trim();
+  const dashboardApp = openFirebaseDashboardApp();
+  const database = dashboardApp.database();
 
   return database.ref('coverage-reports').child(latestSha).set(results)
-    .then(() => database.goOffline(), () => database.goOffline());
+    .catch((err: any) => console.error(err))
+    .then(() => dashboardApp.delete());
 }
 
 // TODO(devversion): In the future we might have a big database where we can store full summaries.

tools/gulp/tasks/payload.ts

@@ -4,7 +4,7 @@ import {statSync} from 'fs';
 import {DIST_ROOT} from '../constants';
 import {spawnSync} from 'child_process';
 import {isTravisMasterBuild} from '../util/travis-ci';
-import {openFirebaseDashboardDatabase} from '../util/firebase';
+import {openFirebaseDashboardApp} from '../util/firebase';
 
 const bundlesDir = join(DIST_ROOT, 'bundles');
 
@@ -47,10 +47,12 @@ function getFilesize(filePath: string) {
 
 /** Publishes the given results to the firebase database. */
 function publishResults(results: any) {
-  let latestSha = spawnSync('git', ['rev-parse', 'HEAD']).stdout.toString().trim();
-  let database = openFirebaseDashboardDatabase();
+  const latestSha = spawnSync('git', ['rev-parse', 'HEAD']).stdout.toString().trim();
+  const dashboardApp = openFirebaseDashboardApp();
+  const database = dashboardApp.database();
 
   // Write the results to the payloads object with the latest Git SHA as key.
   return database.ref('payloads').child(latestSha).set(results)
-    .then(() => database.goOffline(), () => database.goOffline());
+    .catch((err: any) => console.error(err))
+    .then(() => dashboardApp.delete());
 }

tools/gulp/tasks/screenshots.ts

@@ -25,14 +25,14 @@ const FIREBASE_STORAGE_GOLDENS = 'goldens';
 
 /** Task which upload screenshots generated from e2e test. */
 task('screenshots', () => {
-  let prNumber = process.env['TRAVIS_PULL_REQUEST'];
+  const prNumber = process.env['TRAVIS_PULL_REQUEST'];
 
   if (isTravisMasterBuild()) {
     // Only update goldens for master build
     return uploadScreenshots();
   } else if (prNumber) {
-    let firebaseApp = connectFirebaseScreenshots();
-    let database = firebaseApp.database();
+    const firebaseApp = connectFirebaseScreenshots();
+    const database = firebaseApp.database();
 
     return updateTravis(database, prNumber)
       .then(() => getScreenshotFiles(database))
@@ -40,7 +40,8 @@ task('screenshots', () => {
       .then((results: boolean) => updateResult(database, prNumber, results))
       .then(() => uploadScreenshotsData(database, 'diff', prNumber))
       .then(() => uploadScreenshotsData(database, 'test', prNumber))
-      .then(() => database.goOffline(), () => database.goOffline());
+      .catch((err: any) => console.error(err))
+      .then(() => firebaseApp.delete());
   }
 });
 

tools/gulp/util/firebase.ts

@@ -5,11 +5,11 @@ const cloudStorage = require('@google-cloud/storage');
 // Firebase configuration for the Screenshot project. Use the config from the screenshot functions.
 const screenshotFirebaseConfig = require('../../screenshot-test/functions/config.json');
 
-/** Opens a connection to the firebase realtime database. */
-export function openFirebaseDashboardDatabase() {
+/** Opens a connection to the Firebase dashboard app. */
+export function openFirebaseDashboardApp() {
   // Initialize the Firebase application with firebaseAdmin credentials.
   // Credentials need to be for a Service Account, which can be created in the Firebase console.
-  firebaseAdmin.initializeApp({
+  return firebaseAdmin.initializeApp({
     credential: firebaseAdmin.credential.cert({
       project_id: 'material2-dashboard',
       client_email: 'firebase-adminsdk-ch1ob@material2-dashboard.iam.gserviceaccount.com',
@@ -19,8 +19,6 @@ export function openFirebaseDashboardDatabase() {
     }),
     databaseURL: 'https://material2-dashboard.firebaseio.com'
   });
-
-  return firebaseAdmin.database();
 }
 
 /**