Permissions Error with Cloud Function Adding Data to Firestore

Question

I'm trying to setup a Cloud Function that, when ran by Cloud Scheduler, will insert certain data into my Firestore Database. I am doing this in Node.js using the Inline editor provided when creating my Cloud Function.

I keep getting the error:

"Error: function crashed. Details: 7 PERMISSION_DENIED: Missing or insufficient permissions."

On my Firebase dashboard, the logs show my function and the error that I get when I test my Cloud Function, so I'm assuming my function is hitting the database, just not adding the dummy data I was testing with.

index.js:

const Firestore = require('@google-cloud/firestore');
const PROJECTID = 'MY_PROJECT_ID';
const firestore = new Firestore({
  projectId: PROJECTID,
  timestampsInSnapshots: true,
});

/**
 * Responds to any HTTP request.
 *
 * @param {!express:Request} req HTTP request context.
 * @param {!express:Response} res HTTP response context.
 */
exports.helloWorld = (req, res) => {
    return firestore.collection("users").add({
    first: "Ada",
    last: "Lovelace",
    born: 1815
    });
};

Package.json:

{
  "name": "sample-http",
  "version": "0.0.1",
  "dependencies": {
    "@google-cloud/firestore": "0.17.0",
    "semver": "^5.5.1"
  }
}

I also have my rules set for my database as:

service cloud.firestore {
  match /databases/{database}/documents {
    match /{document=**} {
        allow read, write;
    }
  }
}

Answer 1

Thanks to @andresmijares I was able to fix my problem. I looked more into the quickstart and changed my index.js as follows (specifically everything before the helloWorld function).

const admin = require('firebase-admin');

admin.initializeApp({
  credential: admin.credential.applicationDefault()
});

const db = admin.firestore();

/**
 * Responds to any HTTP request.
 *
 * @param {!express:Request} req HTTP request context.
 * @param {!express:Response} res HTTP response context.
 */
exports.helloWorld = (req, res) => {
/*  let message = req.query.message || req.body.message || 'Hello World!';
  res.status(200).send(message);
  */
    return db.collection("users").add({
    first: "Ada",
    last: "Lovelace",
    born: 1815
    });
};

And I got the error

"Code in file index.js can't be loaded. Did you list all required modules in the package.json dependencies? Detailed stack trace: Error: Cannot find module 'firebase-admin'"

Which I was able to fix by adding the 'firebase-admin' dependency into my package.json, as follows:

{
  "name": "sample-http",
  "version": "0.0.1",
    "dependencies": {
    "semver": "^5.5.1",
    "@google-cloud/firestore": "^1.3.0",
    "firebase-admin": "^7.1.1"
  }
}

This was also all done in the inline editor provided when creating my Cloud Function, so no installation of anything was needed.

Answer 2

you need to download the sdk key, this is a json file that you can export from your firebase console Project Overview -> Project Settings -> Services Accounts

Then you can instantiate it like this:

var admin = require("firebase-admin");

var serviceAccount = require("path/to/serviceAccountKey.json");

admin.initializeApp({
  credential: admin.credential.cert(serviceAccount)
});

When using the firebase admin sdk, the firestore security rules do not apply (they are only for client-side operations)