The problem: sending notifications to the owner of the expired listing The solution: target pub/sub - publish messages with Cloud scheduler on 11 pm daily create topic/subscription - "cron-topic" / " sub_push_cron " delivery type: push ( pull ) setup endpoint on backend NodeJS use NGROK to make the local NODE server available for Google Pub/Sub https://3274d032fcc7.ngrok.io/copper?token=YOUR_TOKEN_00hfMQOXpD axios Graphql API: processExpiredListins (getExpiredListins => owners => sendNotificaton) The Benefit: why no cloud function needed? https://cloud.google.com/scheduler/docs/tut-pub-sub Firebase Emulator