Firebase CronJobs - how to allow http triggers from one cronjob site - firebase

Question

Since Firebase (Real-time DB) does not support cron-jobs I am using cron-job.org to schedule http triggers. This function should fire once at the end of every day, so at around 11:55pm. The thing is I would like only cron-job.org to be able to trigger the http endpoint and no one else (e.g. someone malicious trying to trigger it many times a day). How can I achieve this in my cloud function?
I have setup the cronjob and this is all the code I have right now:
exports.findAndDeleteSevenDayJobs = functions.https.onRequest((req, res) => {
console.log('req',req);
});
Also, cron-job.org offers this:
And I have no idea how to use it.

Answer 1

To create cron-jobs in firebase RDB use a third party service like cron-job.org
1) CREATING THE KEY
To make everything secure you have to generate a secure key, from now on called YourSelfGeneratedButSecureKey.
You can generate one in your terminal by typing: node -e "console.log(require('crypto').randomBytes(20).toString('hex'))"
2) CREATING CRON JOB
Create a new cron-job that will hit your cloud function end-point and attach the created key as a url-query like so:
https://{projectSpecific}.cloudfunctions.net/{nameOfFunction}?key={YourSelfGeneratedButSecureKey}
Setup the key into your env by using the following command in your terminal:
firebase functions:config:set cron.key="{YourSelfGeneratedButSecureKey}"
3) CLOUD FUNCTION
To make sure everything is maximum security you can install secure-compare by typing npm install --save secure-compare;
Then in your cloud function:
const secureCompare = require('secure-compare');
exports.{nameOfFunction} = functions.https.onRequest((req, res) => {
const { key } = req.query;
if (!secureCompare(key, functions.config().cron.key)) {
console.log('Key in request and in env do NOT match');
res.status(403).send('Security key does not match.');
return null;
}
// DO REPETITIVE STUFF SECURELY
});