Firebase PubSub function to create a daily backup of all firestore collections, taken from https://firebase.google.com/docs/firestore/solutions/schedule-export

backupFirestoreDaily.js

import functions from 'firebase-functions'
import firestore from '@google-cloud/firestore'
// noinspection JSUnresolvedVariable
const client = new firestore.v1.FirestoreAdminClient()

const bucket = 'gs://backup_firestore_daily'

export const scheduledFirestoreExport = functions.pubsub
    .schedule('0 0 * * *')
    .timeZone('America/Toronto')
    .onRun(() => {

        const projectId = process.env.GCP_PROJECT || process.env.GCLOUD_PROJECT
        const databaseName = client.databasePath(projectId, '(default)')

        return client.exportDocuments({
            name: databaseName,
            outputUriPrefix: bucket,
            collectionIds: []
        })
            .then(responses => {
                const response = responses[0]
                console.log(`Operation Name: ${response['name']}`)
                return 1
            })
            .catch(err => {
                console.error(err)
                throw new Error('Export operation failed')
            })
    })