Unable to start SQL Connect within ExpressJS Backend hosted in Functions

[ssjh23]

Hi, I am new to the Firebase Ecosystem so please bear with me. I am trying to run an ExpressJS server within a cloud function, and I am trying to connect SQL Connect service to the server within the function. However I am running into the below issue:

[REQUIRED] Environment info

firebase-tools: 15.17.0

Platform: Windows
Node Version: 22.22.0
Typescript: ^5.7.3
Firebase admin: 13.6.0
Firebase Functions: ^7.0.0

[REQUIRED] Test case

1. Run an ExpressJS with TS server inside a firebase function. I followed the guide here: https://firebase.google.com/docs/functions/http-events

import functions from "firebase-functions/v2/https";

const express = require('express');
const app = express();

// Expose Express API as a single Cloud Function:
export const be= functions.onRequest(app);

2. Initialise the Firebase SQL Connect SDK using the Manual Installation instructions given here
   https://firebase.google.com/docs/sql-connect/quickstart?userflow=manual#code-examples

3. Modify the code such that it calls InitializeApp(), and then the GetDataConnect

import functions from "firebase-functions/v2/https";

const express = require('express');
const app = express();
try {
  firebaseApp = getApp();
} catch (error) {
  firebaseApp = initializeApp();
}
app.use(cors({origin: true}));

if (!firebaseApp) {
  throw new Error("Failed to initialize Firebase app");
}

const dataConnect = getDataConnect(connectorConfig);
// [Optionally] Configure the SDK to use Data Connect local emulator.
connectDataConnectEmulator(dataConnect, 'localhost', **9399)**

// Expose Express API as a single Cloud Function:
export const be= functions.onRequest(app);

[REQUIRED] Steps to reproduce

1. With the previous code setup, and Typescript installed on the server, run tsc && firebase emulators:start

[REQUIRED] Expected behavior

App to start as per normal with Firebase function emulator able to connect to SQL Connect emulator

[REQUIRED] Actual behavior

Receiving the below logs

**FirebaseError: Firebase: No Firebase App '[DEFAULT]' has been created - call initializeApp() first (app/no-app).
    at Object.getApp (D:\repos\Presence\presence_be\node_modules\@firebase\app\dist\index.cjs.js:729:29)
    at getDataConnect (D:\repos\Presence\presence_be\node_modules\@firebase\data-connect\dist\index.node.cjs.js:3062:21)
    at Object.<anonymous> (D:\repos\Presence\presence_be\functions\lib\index.js:60:55)
    at Module._compile (node:internal/modules/cjs/loader:1706:14)
    at Object..js (node:internal/modules/cjs/loader:1839:10)
    at Module.load (node:internal/modules/cjs/loader:1441:32)
    at Function._load (node:internal/modules/cjs/loader:1263:12)
    at TracingChannel.traceSync (node:diagnostics_channel:328:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:237:24)
    at Module.require (node:internal/modules/cjs/loader:1463:12) {
  code: 'app/no-app',
  customData: { appName: '[DEFAULT]' }
}

[ssjh23]

Apologies also if not using the correct type tag, I was not able to find the question tag when creating the issue

[aalej]

Hey @ssjh23, thanks for reaching out to us. Don't worry about the tags, I think for now we can tag it as type: bug while we're looking into the issue.

The error you shared usually means that you are trying to use a method in the Admin SDK without first calling initializeApp(). Although, looking at the code you shared, I see that there is a initializeApp().

I'm currently working on reproducing this, but I'm encountering a couple of different errors running the code snippets you shared, so I created this small MCVE that is similar to the app you're trying to run. It runs an express server that has some endpoints that connect to SQL Connect. Could you try running this to see if this is similar to what you are doing?

By any chance, could you share a minimal reproducible example with us? This will help us better understand if the issue could be related to firebase-tools, firebase-admin SDK, or something else.

[ssjh23]

Hi @aalej, firstly thanks for your prompt reply.

I followed the MCVE you have provided, and am now able to run the project. Comparing your code and mine, the main difference is the source of the getDataConnect.

I am able to replicate my issue if I were to replace the getDataConnect function when its taken from firebase/data-connect instead of firebase-admin/data-connect. For me, the non-admin version does not allow me to pass the app returned from initializeApp into the function, which I can guess is what is throwing the error, however I used the non-admin version as per the documentation example.

You may refer to below as the MCVE

import { onRequest } from "firebase-functions/https";
import { initializeApp } from "firebase-admin/app";
import { getDataConnect } from "firebase/data-connect";
import express from "express";

const expressApp = express();
initializeApp();
getDataConnect(
  {
      *Replace with your config*
  },
);

export const api = onRequest(expressApp);

And run it as how you would in your example.

Maybe some questions I would also have is that:

1. When do I use the admin vs non-admin version (or point me to the appropriate docs for me to read)
2. Following your MCVE structure, if I were to run the SDK generation function, should I be running it within the functions folder, or on my root project directory? I observe that the difference is that within the functions folder, only dataconnect-admin-generated is created, but outside both that and dataconnect-generated is made in the root directory.

Thank you

[aalej]

Thanks for sharing a code snippet @ssjh23! It looks like the the reason why the error is occurring is because you are importing the Firebase's Client SDK(firebase/data-connect), which is meant for web browsers. This would cause errors since firebase-admin and firebase libraries were designed to work in different environments(server vs client).

To answer your questions

1. When do I use the admin vs non-admin version (or point me to the appropriate docs for me to read)

Since you're running on a Node.js server, using the Firebase Admin SDK(firebase-admin/data-connect) would be the correct choice since it was made to run on server environments. If you were running on a web client, then you would use the Firebase's Client SDK(firebase/data-connect) instead. Here's our guide on how to use the Admin SDK to connect with SQL Connect

2. Following your MCVE structure, if I were to run the SDK generation function, should I be running it within the functions folder, or on my root project directory? I observe that the difference is that within the functions folder, only dataconnect-admin-generated is created, but outside both that and dataconnect-generated is made in the root directory.

The output of firebase dataconnect:sdk:generate should be the same even if you run it on either project root or functions directory. The expected behavior would be that it would generate the src/dataconnect-admin-generated folder in your functions directory. It should look something like

.
├── dataconnect
│   ├── dataconnect.yaml
│   ├── example
│   │   ├── connector.yaml
│   │   ├── mutations.gql
│   │   └── queries.gql
│   └── schema
│       └── schema.gql
├── dataconnect-debug.log
├── firebase.json
├── functions
│   ├── lib
│   │   ├── index.js
│   │   └── index.js.map
│   ├── package-lock.json
│   ├── package.json
│   ├── src
│   │   ├── dataconnect-admin-generated
│   │   └── index.ts
│   └── tsconfig.json
├── pglite-debug.log
└── README.md

Just to verify, could you share what your folder structure looks like after running the firebase dataconnect:sdk:generate? If the behavior is different when running on project root vs functions folder, then we might have a bug that occurs on Windows machines.