fs_emulator_connect.js snippet doesn't work

[christiangenco]

I'm following the Connect your app to the Cloud Firestore Emulator guide to try to make unit tests for my cloud functions.

After starting my emulator with npm run serve which runs firebase emulators:start --only functions,firestore,storage (and verifying that it works from the web interface) I tried to run this snippet:

snippets-web/snippets/firestore-next/emulator-suite/fs_emulator_connect.js

Lines 8 to 12 in 509769a

	import { getFirestore, connectFirestoreEmulator } from "firebase/firestore";
	// firebaseApps previously initialized using initializeApp()
	const db = getFirestore();
	connectFirestoreEmulator(db, 'localhost', 8080);

That code throws the error FirebaseError: Firebase: No Firebase App '[DEFAULT]' has been created - call Firebase App.initializeApp() (app/no-app)..

Alright fine I'll ignore the firebaseApps previously initialized using initializeApp() comment like another open issue noticed and initialize the app:

const { initializeApp } = require("firebase/app");
const {
  getFirestore,
  connectFirestoreEmulator,
} = require("firebase/firestore");

// firebaseApps previously initialized using initializeApp() and apparently they still do, too
initializeApp();
const db = getFirestore();
connectFirestoreEmulator(db, "localhost", 8080);

That code throws [FirebaseError: "projectId" not provided in firebase.initializeApp.]. Alright fine I'll change initializeApp() to initializeApp({ projectId: "anything-can-go-here" }) and now the code isn't crashing.

Sweet! Seems like we're getting somewhere. Let's add some code to try to actually write something to the database...

const { initializeApp } = require("firebase/app");
const {
  getFirestore,
  connectFirestoreEmulator,
  doc,
  setDoc,
} = require("firebase/firestore");

initializeApp({ projectId: "emulator" });
const db = getFirestore();
connectFirestoreEmulator(db, "localhost", 8080);

async function main() {
  const ref = doc(db, "tests/foo");
  const res = await setDoc(ref, { foo: "bar" });
  console.log({ res, ref });
}
main();

But now that throws FirebaseError: 7 PERMISSION_DENIED: No matching allow statements even though my firestore.rules is totally open:

rules_version = '2';

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

I found an old related issue that seems to be saying that throwing PERMISSION_DENIED is expected behavior unless you're authenticating as an admin, which you can emulate by passing an "Authorization: Bearer owner" header, but the code to do that looks nothing like in this snippet so I don't know how to integrate it. Maybe I can pass customHeaders into getFirestore? Who knows!

In any case, I don't think this snippet works as it's written.

What's a working example of connecting to the firestore emulator from node?

[christiangenco]

For anyone that stumbled on this issue from google and would like to get something working now: I was able to connect to my local emulator and write to firestore by adapting some code posted on a related issue by thMthMnky:

const admin = require("firebase-admin");
admin.initializeApp({ projectId: "your-project-id" });

const db = admin.firestore();
db.settings({
  host: "localhost:8080",
  ssl: false,
});

async function main() {
  const ref = db.doc("tests/test");
  const res = await ref.set({ foo: "baz" });
}
main();

It's very important that the projectId you pass in admin.initializeApp matches what your emulator thinks your projectId is. If they don't match your writes will still go through but won't be reflected in the database.

I can't figure out where the emulator stores that projectId or how to change it (I think it's in .firebaserc?), but you can see what the emulator thinks its' projectId is when you first open the emulator web UI in an incognito window:

[christiangenco]

Oh my gosh I can't believe it but the problem was that I wasn't on the latest version of firebase-admin in my package.json. I was on 9.something and upgrading to 10.0.2 with yarn upgrade --latest firebase-admin made the example code start working.

Here's the minimal code to write to emulator storage and firestore:

const { initializeApp } = require("firebase-admin/app");
const { getStorage } = require("firebase-admin/storage");
const { getFirestore } = require("firebase-admin/firestore");

initializeApp();

const bucket = getStorage().bucket("gs://default-bucket/");
const db = getFirestore();

async function main() {
  await bucket.file("test.txt").save("lol hi");
  await db.doc("tests/foo").set({ foo: "bar" });
}
main();

Make sure you invoke that code setting the FIREBASE_STORAGE_EMULATOR_HOST, FIRESTORE_EMULATOR_HOST, and GCLOUD_PROJECT environment variables like this:

FIREBASE_STORAGE_EMULATOR_HOST="localhost:9199" FIRESTORE_EMULATOR_HOST="localhost:8080" GCLOUD_PROJECT="your-project-id" node test.js