尝试通过 Next.js API 路由上的 admin.firestore.v1.FirestoreAdminClient 导出备份。 错误：无法加载默认凭据

Question

I'm trying to run this code to implement a Firestore backup.

But for the first time, I'm deploying it into a Next.js project.

I'll hit it on my /api/backup endpoint.

const backupHandler: NextApiHandler = async (req,res) => {
  try {
  
    const admin = initializeFirebaseAdmin();
    const PROJECT_ID = getProjectId();
    
    const client = new admin.firestore.v1.FirestoreAdminClient();
    const DB_NAME = client.databasePath(PROJECT_ID, '(default)');

    const TODAY = getToday();  // YYYY-MM-DD
    const hashId = generateId().slice(0,5);
    const BUCKET = `gs://${PROJECT_ID}.appspot.com`;
    const FOLDER = `firestore-backup/${TODAY}-${hashId}`;
    const FULL_PATH = `${BUCKET}/${FOLDER}`;

    await client.exportDocuments({
      name: DB_NAME,
      outputUriPrefix: FULL_PATH,
      collectionIds: [] // CAN LIST SPECIFIC COLLECTIONS
    });

    console.log(`Backup successfully exported`);
    return res.status(200).send("Ok");
    
  }
  catch(err) {
    console.log(err);
    return res.status(500).send("Server error");
  }
  
};

This is the initializeFirebaseAdmin() function

type FirebaseAdmin = typeof import("firebase-admin/lib/firebase-namespace")

const getServiceAccount = () : admin.ServiceAccount => {
  if (process.env.VERCEL_ENV === "production"
  ||  process.env.VERCEL_GIT_COMMIT_REF === "staging")  {
    return SERVICE_ACCOUNT.PROD;
  }
  else return SERVICE_ACCOUNT.TEST;
};

export const initializeFirebaseAdmin = (): FirebaseAdmin => {
  const account = getServiceAccount();  // THIS GETS THE SERVICE ACOUNT (VIA THE DOWNLOADED .json FILE)
  const PROJECT_ID = getProjectId();
  if (!admin.apps.length) {
    admin.initializeApp({
      credential: admin.credential.cert(account),
      databaseURL: `https://${PROJECT_ID}.firebaseio.com`  // I TRIED WITH AND WITHOUT THIS LINE: SAME RESULT
    });
  }
  return admin;
};

This is the error I'm getting:

Error: Could not load the default credentials. Browse to https://cloud.google.com/docs/authentication/getting-started for more information. at GoogleAuth.getApplicationDefaultAsync (/var/task/node_modules/google-auth-library/build/src/auth/googleauth.js:173:19)

At first I was just using the credential property. Then I added the databaseURL to see if it would solve the issue, but still, same result.

I think I'm initializing the firebase-admin properly. Not sure what is going wrong here.

---

UPDATE: Just found out that this very same code works fine on my local environment (in development), but does not work on my Next.js Node.js environment when I deploy it. What could be going wrong?

Answer 1

After days in hell, just found out what I was doing wrong.

I'm using new admin.firestore.v1.FirestoreAdminClient(); because firebase-admin itself won't expose any methods for us to access the exportDocuments() functionality.

But the fact is, when you instantiate the FirestoreAdminClient like that, it will not have access to the credentials that you've used on admin.initializeApp({credentials}) .

So you need to pass the credentials to the client, by doing:

import * as admin from "firebase-admin";  // OR IMPORT IT FROM SOME SINGLETON initializeFirebaseAdmin FUNCTION
import { NextApiHandler } from "next";
import SERVICE_ACCOUNT from "some-path/serviceAccount.json";

interface CredentialBody { // COPIED THIS FROM google-auth-library > auth > credentials
  client_email?: string;
  private_key?: string;
}

const backupHandler: NextApiHandler = async (req,res) => {

  const client = new admin.firestore.v1.FirestoreAdminClient({
    credentials: SERVICE_ACCOUNT as CredentialBody    // <<<<<< THIS IS THE IMPORTANT PART
  });

  const PROJECT_ID = getProjectId();
  const DB_NAME = client.databasePath(PROJECT_ID, "(default)");

  const TODAY = getToday();  // YYYY-MM-DD
  const hashId = generateId().slice(0,5);
  const BUCKET = `gs://${PROJECT_ID}.appspot.com`;
  const FOLDER = `backup/${TODAY}-${hashId}`;
  const FULL_PATH = `${BUCKET}/${FOLDER}`;

  await client.exportDocuments({
    name: DB_NAME,
    outputUriPrefix: FULL_PATH,
    collectionIds: [] // CAN LIST SPECIFIC COLLECTIONS
  });

  console.log(`Backup successfully exported`);
  return res.status(200).send("Ok");

};