CODEWITHSUNDEEP
google-cloud-functionsfirebase-hosting
Amy
Amy

Reputation: 11

Calling Firebase Hosting API from a Firebase Cloud Function

I have a Firebase (node.js) cloud function that pulls in some data from my app's Firestore database and builds some static content for the web. I'd like that same cloud function to deploy the static content to Firebase hosting via the Firebase Hosting API, creating a static portion of my site with user generated content.

I understand the general flow thanks to the somewhat clear walkthrough, but am stuck on the first step: getting an access token to call the API. Obviously I'm not going to insecurely put my service account key in the cloud function itself, so the example in the walkthrough doesn't apply. And as I understand it, Firebase cloud functions are already associated with a service account, so presumably there's some way to get an access token to call other Google Cloud services from a cloud function.

So how do I get an access token to call the hosting API from a Cloud Function?

There are some red flags that make me think this isn't possible. For example, all of the uses cases in the walkthrough allude to other server environments, as opposed to Google Cloud environments. And yet, this use case is the third bullet in the use case list in the walkthrough.

I've searched extensively here and elsewhere for some guidance, but aren't finding anything. There are some older questions about accessing hosted files from a cloud function that aren't relevant. This promising question from 5 years ago about this exact use case only has dead ends.

Upvotes: 1

Views: 117

Answers (1)

Dharmaraj
Dharmaraj

Reputation: 50930

You can use the google-auth-library package in Cloud Functions to a get a token as shown below:

import { GoogleAuth } from "google-auth-library";

const token = await new GoogleAuth({
  scopes: ["https://www.googleapis.com/auth/cloud-platform"],
}).getAccessToken();

If you use Firebase Admin SDK in the Cloud Functions, then you can get an access token of the default service account as shown below (do ensure the service account has required permissions):

import { initializeApp } from "firebase-admin/app";

const admin = initializeApp();
const token = await admin.options.credential?.getAccessToken();
// ^ Google OAuth2 access token object used to authenticate with Firebase services.

Upvotes: 1

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