为什么当 Node.JS 应用程序与 Firebase 集成时它会崩溃？

Question

First, I've followed Express Getting started and developed a Hello World application. Second, I've followed Firebase 's guide for Node.JS apps and configured Cloud Functions .

Ending up with the following project structure.

> bin/
  > www.js
> src/
  > controllers
  > routes
  > more modules
> test/
  > src
> functions/
  > index.js
  > package.json
> app.js
> package.json

The content of functions/index.js is:

const functions = require('firebase-functions');
const app = require('../app');
exports.app = functions.https.onRequest(app);

Now, when trying to deploy it fails with the next error.

Cannot find module '../app'

Answer 1

Root cause

Cloud Functions uploads the content of the functions/ directory on deployment and so there was no Node.JS app inside it.

Solutions

There's a couple of ways to solve it . One way is by copying the app before deploy, following the steps.

1. Update the app's path in index.js.

    -- const app = require('../app'); ++ const app = require('./app');

2. All dependencies (do not confuse with devDependencies ) from package.json must be installed at functions/package.json . For example: if @google-cloud/firestore is declared as an app's dependency then it must be installed as follows.

    cd functions && npm i @google-cloud/firestore

3. Copy the app, before deployment, into the Functions module. This can be done via the firebase.json file by updating it with the following block.

    "functions": { "predeploy": "mkdir functions/app && cp -r {app.js,src} functions/app", "postdeploy": "rm -r functions/app" }

Now deploying again will work.

firebase deploy # success!

What is happening is that the Node.JS app is copy and pasted just before the deploy step is ran. Then the deployment uploads not only the functions but also the required app into the cloud. Then when the functions are executed, the app too.

Impact

As mentioned at step #2, the app's dependencies are installed also at the Functions module. Otherwise the deployment will fail due missing dependencies. package.json is used locally whereas functions/package.json is used on the cloud. By following this approach, you need to keep track of dependencies and make sure same ones are installed in both modules.

Source

3 Ways To Integrate a Node.JS App With Firebase