GoogleCloudPubSub

GoogleCloudPubSub is a PubSub implementation backed by Google Cloud Pub/Sub. It delivers events across processes and hosts using Google Cloud topics and subscriptions, with ordered delivery and message acknowledgment.

Use it for distributed deployments on Google Cloud. For single-process delivery, use EventEmitterPubSub. For Redis, use RedisStreamsPubSub.

Each topic maps to a Google Cloud topic. Subscriptions with a group share a subscription. Members compete for events. Subscriptions without a group create a per-instance subscription. Every instance receives every event.

Installation

npm

npm install @mastra/google-cloud-pubsub

pnpm

pnpm add @mastra/google-cloud-pubsub

Yarn

yarn add @mastra/google-cloud-pubsub

Bun

bun add @mastra/google-cloud-pubsub

Usage example

Pass a Google Cloud client configuration, such as a project ID.

src/mastra/index.ts

import { Mastra } from '@mastra/core'
import { GoogleCloudPubSub } from '@mastra/google-cloud-pubsub'

export const mastra = new Mastra({
  pubsub: new GoogleCloudPubSub({
    projectId: 'my-project',
  }),
})

Constructor parameters

config:

ClientConfig

Configuration for the Google Cloud Pub/Sub client, including credentials and project ID. See the @google-cloud/pubsub client documentation for all fields.

Methods

GoogleCloudPubSub implements the PubSub contract. The methods below are specific to this implementation.

init(topicName, group?)

Creates the topic and a subscription if they don't already exist, and returns the subscription. subscribe calls this internally, so you rarely call it directly.

await pubsub.init('workflow.events')

subscribe(topic, cb, options?)

Subscribes to a topic. With options.group, members of the group share a subscription and compete for events. Without a group, the instance receives every event through its own subscription.

await pubsub.subscribe('workflow.events', (event, ack, nack) => {
  console.log(event)
})

flush()

Waits for pending acknowledgments to complete.

await pubsub.flush()

destroy(topicName)

Removes the subscription and topic for a topic name. Use this to clean up Google Cloud resources.

await pubsub.destroy('workflow.events')

Acknowledgment

Each delivered event includes ack and nack functions. Call ack after successful processing to remove the event from the subscription. When neither is called, Google Cloud redelivers the event after its acknowledgment deadline expires.