AWS Lambda Nest Microservice Essentials

bootstrapper.ts

import { NestFactory } from '@nestjs/core';
import { ExpressAdapter } from '@nestjs/platform-express';
import { INestApplication } from '@nestjs/common';
import { AppModule } from './app.module';
import { Express } from 'express';
import * as express from 'express';
import { createServer } from 'aws-serverless-express';
import { IBootstrapper } from './abstract/IBootstrapper';
import { Server } from 'http';

export class NestBootstrapper implements IBootstrapper {
  private cachedServer: Server;

  private async createExpressApp(
    expressApp: Express,
  ): Promise<INestApplication> {
    const app = await NestFactory.create(
      AppModule,
      new ExpressAdapter(expressApp),
    );
    return app;
  }

  public async bootstrap(): Promise<Server> {
    if (!this.cachedServer) {
      const expressApp = express();
      const app = await this.createExpressApp(expressApp);
      await app.init();
      this.cachedServer = createServer(expressApp);
    }
    return this.cachedServer;
  }
}

Dockerfile

FROM public.ecr.aws/lambda/nodejs:16

COPY package.json nest-cli.json tsconfig.build.json tsconfig.json src/ ${LAMBDA_TASK_ROOT}/

RUN npm i

RUN npm run build

CMD [ "dist/main.handler" ]

IBootstrapper.ts

import { Server } from 'http';

export interface IBootstrapper {
  /**
   * Bootstraps the application.
   */
  bootstrap(): Promise<Server>;
}

main.ts

import { Context } from 'aws-lambda';
import { proxy, Response } from 'aws-serverless-express';
import { NestBootstrapper } from './bootstrapper';

export async function handler(event: any, context: Context): Promise<Response> {
  const bootstrapper = new NestBootstrapper();
  const server = await bootstrapper.bootstrap();
  return proxy(server, event, context, 'PROMISE').promise;
}

package.json

{
  "name": "my-microservice",
  "version": "0.0.1",
  "description": "",
  "author": "",
  "private": true,
  "license": "UNLICENSED",
  "scripts": {
    "build": "nest build",
    "format": "prettier --write \"src/**/*.ts\" \"test/**/*.ts\"",
    "start": "nest start",
    "start:dev": "nest start --watch",
    "start:debug": "nest start --debug --watch",
    "start:prod": "node dist/main",
    "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix"
  },
  "dependencies": {
    "@aws-sdk/client-dynamodb": "^3.252.0",
    "@aws-sdk/lib-dynamodb": "^3.252.0",
    "@nestjs/common": "^9.0.0",
    "@nestjs/core": "^9.0.0",
    "@nestjs/platform-express": "^9.0.0",
    "@types/aws-lambda": "^8.10.109",
    "@types/aws-serverless-express": "^3.3.5",
    "@types/uuid": "^9.0.0",
    "aws-lambda": "^1.0.7",
    "aws-serverless-express": "^3.4.0",
    "nest": "^0.1.6",
    "reflect-metadata": "^0.1.13",
    "rxjs": "^7.2.0",
    "uuid": "^9.0.0"
  },
  "devDependencies": {
    "@nestjs/cli": "^9.0.0",
    "@nestjs/schematics": "^9.0.0",
    "@nestjs/testing": "^9.0.0",
    "@types/express": "^4.17.13",
    "@types/jest": "29.2.4",
    "@types/node": "18.11.18",
    "@types/supertest": "^2.0.11",
    "@typescript-eslint/eslint-plugin": "^5.0.0",
    "@typescript-eslint/parser": "^5.0.0",
    "eslint": "^8.0.1",
    "eslint-config-prettier": "^8.3.0",
    "eslint-plugin-prettier": "^4.0.0",
    "jest": "29.3.1",
    "prettier": "^2.3.2",
    "source-map-support": "^0.5.20",
    "supertest": "^6.1.3",
    "ts-jest": "29.0.3",
    "ts-loader": "^9.2.3",
    "ts-node": "^10.0.0",
    "tsconfig-paths": "4.1.1",
    "typescript": "^4.7.4"
  },
  "jest": {
    "moduleFileExtensions": [
      "js",
      "json",
      "ts"
    ],
    "rootDir": "src",
    "testRegex": ".*\\.spec\\.ts$",
    "transform": {
      "^.+\\.(t|j)s$": "ts-jest"
    },
    "collectCoverageFrom": [
      "**/*.(t|j)s"
    ],
    "coverageDirectory": "../coverage",
    "testEnvironment": "node"
  }
}