Event-Driven NestJS

The repo contains an example NestJS app running on AWS Lambda with an EventBridge source. The use case is a simple service that emails a customer when a payment event is received using Twilio Sendgrid as the email delivery service.

Architecture

AWS Lambda & NestJS

This project uses NestJS Standalone applications with AWS Lambda. NestJS Standalone apps can use the NestJS DI system without starting an entire webserver.

Setup

1. Create a SendGrid account

2. Get a Sendgrid API key

3. Add your Sendgrid API key to the AWS SSM with the prefix /dev/sendgrid/apiKey using the Secure String type.

4. Verify an email domain with Sendgrid

5. Update the serverless.yml file with your verified email domain.

AWS Deployment

export AWS_PROFILE=<YOUR_PROFILE>

# package with webpack
yarn build

npx serverless deploy --stage dev

Webpack

The project uses Webpack to bundle the Typescript for NodeJS. The total bundled deployment size is 1.2mb.

See: https://docs.nestjs.com/faq/serverless#benchmarks

Events

The service reacts to one payments.InvoicePaid event.

The Event-Carried State Transfer pattern is used to pass around the relevant information about the User that's needed to send an email.

Example event:

{
    "version": "0",
    "id": "c82f1e7d-4b0b-9d75-3f11-89be92935a12",
    "detail-type": "payments.InvoicePaid",
    "source": "payments.api",
    "account": "111111111111",
    "time": "2022-12-04T11:22:08Z",
    "region": "us-east-1",
    "resources": [],
    "detail": {
        "user": {
            "id": 1,
            "email": "user@gmail.com"
        }
    }
}