Firebase - Handle cloud events within NestJS Framework

user_1860540 0
Viewed 2018

I'm using NestJS as my backend Framework and Firebase.

To integrate Nest with Firebase on HTTP requests is simple as attaching the express instance of nest to Firebase:

const server: Express = express();

const bootstrap = async (expressInstance: Express) => {
  const app = await NestFactory.create(AppModule, expressInstance);
  await app.listen(3000);
  await app.init();
};

bootstrap(server);

exports.api = functions.https.onRequest(server);

But what about the other Google Functions (such as pubsub, firestore, auth, etc.)?

I'm building a subscription application, and I depend on functions.pubsub to check at the end of every day which subscriptions should I charge. It requires writing business logic that I want to write withing NestJs.

I'm trying to achieve something like this (in a nutshell):

functions.pubsub
    .topic('topic')
    .onPublish(app.getService(Service).method);
google-cloud-functions firebase nestjs
2 Answers

Turns out I was very close to the solution. instead of getService, I had to use get, like so:

const bootstrap = async (expressInstance: Express) => {
  const app = await NestFactory.create(AppModule, expressInstance);
  await app.init();

  return app;
};

const main = bootstrap(server);

export const subscriptions = functions
  .pubsub
  .topic('cron-topic')
  .onPublish((context, message) => main.then(app => {
    return app.get(SubscribeService).initDailyCharges(context, message));
  });
user_18605400

Found a new solution for standalone applications: https://docs.nestjs.com/standalone-applications

You don't need to bootstrap NestJS with Express server to handle PubSub messages.

export const subscriptions = functions
  .pubsub
  .topic('cron-topic')
  .onPublish((context, message) => {
    const app = await NestFactory.create(ApplicationModule);
    return app.get(SubscribeService).initDailyCharges(context, message);
  });
user_11775970
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