NodeJS "Firebase app already exists." error

1. 에러 및 원인

Error: The default Firebase app already exists. This means you called initializeApp() more than once without providing an app name 
as the second argument. In most cases you only need to call initializeApp() once. But if you do want to initialize multiple apps, pass a second argument to initializeApp() to give each app a unique name.

 

nodejs에서 위와 같은 에러가 발생하는 경우, firebase app이 여러번 initialize되어서 생기는 문제이다.

 

2. 해결법

import {initializeApp} from 'firebase-admin/app';
import {credential, apps} from "firebase-admin";

if (!apps.length) {
   initializeApp({
        credential: credential.cert(process.env["GOOGLE_APPLICATION_CREDENTIALS"] ?? ''),
    })
}

apps.length를 통해서 이미 초기화된 app이 있는지 확인한다.