Cloud Functions For Firebase: Functions.pubsub.topic('testtopic').onpublish Not Called

I've copied this code snippet from the official documentation of cloud functions: exports.helloPubSub = functions.pubsub.topic('testTopic').onPublish(event => { return conso

Solution 1:

Firebase (Google) Cloud Messaging and Google Cloud Pub/Sub are different messaging systems, as explained here:

Both are systems to deliver messages, but Google Cloud Messaging is used to deliver messages to and from end-user devices, while Google Cloud Pub/Sub is used to communicate between servers. Google Cloud Messaging is designed to scale to a very large number of delivery end points, but has low throughput (messages per second per channel). Pub/Sub does not have limits on throughput and has a more generic API.

Although they share the concept of topics, a message sent to an FCM topic will not trigger a Pub/Sub Cloud Function.