How to await multiple functions with thousands of promises Firebase Functions

Question

I'm using the below code to delete all old data every night.

Each function works fine on it's own and if I create multiple schedule tasks, one for each function, it also works fine. However, when I combine them into a single Scheduled Task called scheduledCleanData, I'm receiving Error: Could not load the default credentials. Browse to https://cloud.google.com/docs/authentication/getting-started for more information. at GoogleAuth.getApplicationDefaultAsync (/workspace/node_modules/google-auth-library/build/src/auth/googleauth.js:161:19) at process._tickCallback (internal/process/next_tick.js:68:7)

As per this post, I believe this is caused by the functions not waiting for the callbacks, rather than problems with the credentials. However adding async or await keywords cause a parse error. Some of these collections need to delete thousands of records.

Any help how to modify this code to correctly wait would be greatly appreciated!

const functions = require('firebase-functions');
const admin = require('firebase-admin');
const client = require('firebase-tools');
admin.initializeApp(functions.config().firebase)
const db = admin.firestore();

const runtimeOpts = {
    timeoutSeconds: 300,
    memory: '1GB'
}

exports.scheduledCleanData = functions
    .runWith(runtimeOpts)
    .pubsub.schedule('0 3 * * *')
    .timeZone('America/Chicago')
    .onRun((context) => {
        return cleanOldAssignments()
            .then(cleanOldDuties())
            .then(cleanOldEvents())
            .then(console.info("scheduledCleanData Complete!"));
    });

function cleanOldAssignments() {
    const dateYesterday = new Date(new Date().getTime() - (24 * 60 * 60 * 1000));   // 24 hours
    return db.collectionGroup('assignments').where('date', '<', dateYesterday).get()
        .then(querySnapshot => {
            console.info("Old assignments to remove: " + querySnapshot.size);
            const promises = [];
            querySnapshot.forEach(doc => {
                promises.push(doc.ref.delete());
            });
            return Promise.all(promises);
        });
}

function cleanOldDuties() {
    const dateYesterday = new Date(new Date().getTime() - (24 * 60 * 60 * 1000));   // 24 hours
    return db.collectionGroup('duties').where('date', '<', dateYesterday).get()
        .then(querySnapshot => {
            console.info("Old duties to remove: " + querySnapshot.size);
            const promises = [];
            querySnapshot.forEach(doc => {
                promises.push(doc.ref.delete());
            });
            return Promise.all(promises);
        });
}

function cleanOldEvents() {
    const dateYesterday = new Date(new Date().getTime() - (24 * 60 * 60 * 1000));   // 24 hours
    return db.collectionGroup('events').where('date', '<', dateYesterday).get()
        .then(querySnapshot => {
            console.info("Old events to remove: " + querySnapshot.size);
            const promises = [];
            querySnapshot.forEach(doc => {
                promises.push(doc.ref.delete());
            });
            return Promise.all(promises);
        });
}

Answer 1

If cleanOldDuties and cleanOldEvents both return more promises, your code is not taking them into account. You will need to explicitly return their values to propagate down the promise chain:

    return cleanOldAssignments()
        .then(() => { return cleanOldDuties() })
        .then(() => { return cleanOldEvents() })

Without seeing the exact code of these other functions, it's not certain if this will work or not. Those functions have to be implemented correctly as well.

async/await is almost always a clearer way to express these sorts of things. You are probably just using them incorrectly as well.