> For the complete documentation index, see [llms.txt](https://docs.nestjstools.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nestjstools.com/broker-integration/google-pubsub.md).

# Google PubSub

### Google Pub/Sub Channel Integration

The Google Pub/Sub extension for `@nestjstools/messaging` enables cloud-native, event-driven communication across distributed systems. It’s ideal for scalable, serverless-friendly applications that rely on Google Cloud infrastructure.

***

#### 📦 Installation

Install the core messaging package and the Google Pub/Sub extension:

```bash
npm install @nestjstools/messaging @nestjstools/messaging-google-pubsub-extension
```

or

```bash
yarn add @nestjstools/messaging @nestjstools/messaging-google-pubsub-extension
```

***

#### ⚙️ Example Configuration

```ts
import { MessagingModule } from '@nestjstools/messaging';
import { PubSubChannelConfig, MessagingGooglePubSubExtensionModule } from '@nestjstools/messaging-google-pubsub-extension';
import { InMemoryChannelConfig } from '@nestjstools/messaging/channels';
import { SendMessageHandler } from './handlers/send-message.handler';

@Module({
  imports: [
    MessagingGooglePubSubExtensionModule,
    MessagingModule.forRoot({
      messageHandlers: [SendMessageHandler],
      buses: [
        {
          name: 'default.bus',
          channels: ['in-memory', 'pubsub-events'],
        },
      ],
      channels: [
        new InMemoryChannelConfig({
          name: 'in-memory',
          avoidErrorsForNotExistedHandlers: true,
        }),
        new PubSubChannelConfig({
          name: 'pubsub-events',
          projectId: 'your-gcp-project-id',
          topic: 'your-topic-name',
          subscription: 'your-subscription-name',
          middlewares: [],
          autoCreate: true,
          enableSubscriber: true,
          avoidErrorsForNotExistedHandlers: true,
        }),
      ],
      debug: true,
    }),
  ],
})
export class AppModule {}
```

***

#### 🛠️ PubSubChannelConfig Properties

| Property                           | Description                                                               | Default Value |
| ---------------------------------- | ------------------------------------------------------------------------- | ------------- |
| `name`                             | The channel name (e.g., `'pubsub-events'`).                               | —             |
| `projectId`                        | Google Cloud project ID.                                                  | —             |
| `topic`                            | The Pub/Sub topic to publish messages to.                                 | —             |
| `subscription`                     | Subscription name to consume messages from.                               | —             |
| `middlewares`                      | Array of middlewares applied to incoming/outgoing messages.               | `[]`          |
| `autoCreate`                       | Automatically create topic/subscription if they do not exist.             | `true`        |
| `enableSubscriber`                 | Enables the background subscriber to listen to incoming Pub/Sub messages. | `true`        |
| `avoidErrorsForNotExistedHandlers` | Silently skips messages without a matching handler.                       | `false`       |

***

#### 🌐 Key Features

* **Cloud-Native Messaging**: Leverages Google Pub/Sub for reliable, asynchronous communication across microservices.
* **Auto Resource Provisioning**: Automatically creates missing topics and subscriptions when `autoCreate` is enabled.
* **Efficient Scaling**: Suitable for horizontally scaled environments (e.g., Kubernetes, Cloud Run).
* **Graceful Error Handling**: Skip errors when no handler exists by enabling `avoidErrorsForNotExistedHandlers`.
* **Subscriber Control**: Toggle subscriber activation with `enableSubscriber`.


---

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