AutoSNSProducer and SNSProducer

AutoSNSProducer and SNSProducer are two a NestJS utility classes that simplifies the process of publishing messages to AWS SNS.

• SNSProducer: Responsible for publishing messages to Amazon SNS in batches. This class allows easier publishing and testing by delegating configuration to the dependency injection registration.

• AutoSNSProducer: Built on top of SNSProducer, this class will register an EventEmitter2 listener to the event you indicate, will batch messages automatically waiting up to the indicated maximum interval and will handle any errors silently.

Installation

Install the package using your package manager:

npm i @raphaabreu/nestjs-auto-sns-producer

Using AutoSNSProducer

Register the AutoSNSProducer with your NestJS module:

import { AutoSNSProducer } from '@raphaabreu/nestjs-auto-sns-producer-producer';

@Module({
  providers: [
    AutoSNSProducer.register({
      eventName: 'your-event-name',
      topicArn: 'your-topic-arn',
      maxBatchIntervalMs: 10000, // Optional, default is 10000ms
    }),
  ],
})
export class YourModule {}

Now you can produce events and they will be batched then published to SNS automatically:

import { EventEmitter2 } from '@nestjs/event-emitter';

@Injectable()
export class YourService {
  constructor(private readonly eventEmitter: EventEmitter2) {}

  async doWork() {
    // do something

    this.eventEmitter.emit('your-event-name', yourEventData); // Events will be batched to reduce the number of calls to AWS
  }
}

Using SNSProducer

Register the SNSProducer with your NestJS module:

import { SNSProducer } from '@raphaabreu/nestjs-auto-sns-producer';

@Module({
  providers: [
    SNSProducer.register({
      name: 'your-producer-name',
      topicArn: 'your-topic-arn',
      serializer: JSON.stringify, // Optional, default is JSON.stringify
    }),
  ],
})
export class YourModule {}

Inject the SNSProducer into your service and use the publishBatch(messages: T | T[]) method to publish messages:

import { SNSProducer } from '@raphaabreu/nestjs-auto-sns-producer';

@Injectable()
export class YourService {
  constructor(
    @Inject(SNSProducer.getServiceName('your-producer-name'))
    private readonly snsProducer: SNSProducer<YourMessageType>,
  ) {}

  async doWork() {
    const messages: YourMessageType[] = [];

    // ... fill the messages array

    // Messages will be broken down into batches and will be published immediately.
    // The promise returned will complete once all messages are published and will fail if there are any errors.
    await this.snsProducer.publishBatch(messages);
  }
}

Advanced use

Custom Serialization

To use a custom serializer, provide a serializer function in the options:

AutoSNSProducer.register({
  eventName: 'event-1',
  topicArn: 'arn:aws:sns:us-east-1:123456789012:event-1',
  serializer: (event) => `Custom: ${JSON.stringify(event)}`,
});

Custom Message Preparation

To customize how messages are prepared for publishing, provide a prepareEntry function in the options:

AutoSNSProducer.register({
  eventName: 'event-1',
  topicArn: 'arn:aws:sns:us-east-1:123456789012:event-1',
  prepareEntry: (event, index) => ({
    Id: `custom-${index}`,
    Message: JSON.stringify(event),
  }),
});

Tests

To run the provided unit tests just execute npm run tests.

License

MIT License

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

Support

If you have any issues or questions, please open an issue on the project repository.