In today’s cloud-native development landscape, serverless architectures are gaining traction due to their scalability and cost-effectiveness. NestJS, a popular framework for building efficient, scalable Node.js applications, can seamlessly integrate with AWS Lambda and API Gateway for a robust serverless deployment.

In this blog post, we’ll walk through how to deploy a NestJS application using AWS Lambda and API Gateway, automate the deployment using AWS CDK, and troubleshoot common errors.

Introduction to NestJS and Serverless Architecture

What is NestJS?

NestJS is a progressive Node.js framework built on TypeScript, designed to create efficient, scalable, and easily maintainable server-side applications. Its modular architecture, dependency injection, and support for microservices make it an excellent choice for cloud-native development.

What is Serverless Architecture?

Serverless architecture allows developers to build and run applications without managing infrastructure. AWS Lambda is a critical component of serverless architecture, where functions execute code in response to events, scaling automatically with demand. When paired with API Gateway, you can route HTTP requests to Lambda functions, making it an ideal platform for deploying NestJS applications.

Setting Up NestJS for Serverless Deployment

Before deploying NestJS to AWS Lambda, you must configure the application to work in a serverless environment. Here’s how you can do it:

  1. Install Required Packages: Add @nestjs/platform-serverless and serverless-http to your project. These packages enable the NestJS app to run as a Lambda function.
    npm install @nestjs/platform-serverless serverless-http
  2. Modify main.ts: Modify your entry point to create a serverless handler for Lambda.
    import { NestFactory } from ‘@nestjs/core’;

import { AppModule } from ‘./app.module’;

import { Handler, Context, Callback } from ‘aws-lambda’;

import * as serverless from ‘serverless-http’;

let server: Handler;

async function bootstrap() {

  const app = await NestFactory.create(AppModule);

  await app.init();

  return serverless(app.getHttpAdapter().getInstance());

}

export const handler: Handler = async (event: any, context: Context, callback: Callback) => {

  server = server ?? (await bootstrap());

  return server(event, context, callback);

};

  1. Configure Build Output: Adjust your tsconfig.json or nest-cli.json to target Lambda-compatible outputs, bundling only the necessary files.

Integrating NestJS with AWS Lambda

To deploy your NestJS app to Lambda, you must package and upload it to AWS Lambda. This can be done manually, but a framework like AWS CDK or the Serverless Framework is recommended for efficient deployments.

Steps to integrate:

  1. Create a Lambda Function: Use AWS Management Console or CDK to create a Lambda function with appropriate IAM roles and runtime (Node.js 14.x or higher).
  2. Bundle Your NestJS Application: Use tools like Webpack to bundle your NestJS application into a single artifact that can be uploaded to Lambda.
  3. Deploy to Lambda: Upload your code to Lambda and set the handler function appropriately.

Configuring API Gateway for NestJS Lambda Functions

API Gateway acts as the HTTP interface for your Lambda function. It routes incoming HTTP requests to Lambda and passes the response back to the client.

  1. Create a REST API: In the AWS API Gateway, create a new REST API and configure methods for the endpoints you want to expose.
  2. Integrate with Lambda: For each method, select “Lambda Function” as the integration type and point it to your NestJS Lambda function.
  3. Enable CORS: In the API Gateway console, enable CORS to ensure your API is accessible from web browsers.
  4. Deploy API: Deploy the API to a specific stage (e.g., dev or prod).

Automating Deployment with AWS CDK

The AWS Cloud Development Kit (CDK) is a powerful tool for defining your cloud infrastructure in code. Using CDK, you can automate the deployment of your NestJS Lambda function with API Gateway.

  1. Install AWS CDK: If you don’t already have AWS CDK installed, install it using:
    npm install -g aws-cdk
  2. Create a CDK App: Initialize a new CDK app and define your infrastructure in a cdk-stack.ts file.
  3. Define Lambda and API Gateway:
    import * as cdk from ‘aws-cdk-lib’;

import * as lambda from ‘aws-cdk-lib/aws-lambda’;

import * as apigateway from ‘aws-cdk-lib/aws-apigateway’;

export class NestjsServerlessStack extends cdk.Stack {

  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {

    super(scope, id, props);

    const nestJsLambda = new lambda.Function(this, ‘NestJSLambda’, {

      runtime: lambda.Runtime.NODEJS_14_X,

      code: lambda.Code.fromAsset(‘path/to/lambda/code’),

      handler: ‘index.handler’,

    });

    const api = new apigateway.LambdaRestApi(this, ‘NestJsApi’, {

      handler: nestJsLambda,

      proxy: false,

    });

    const items = api.root.addResource(‘items’);

    items.addMethod(‘GET’); // GET /items

  }

}

  1. Deploy Your Stack:
    cdk deploy

This will create your Lambda function, API Gateway, and associated resources in AWS.

Troubleshooting Common Errors in NestJS Lambda Integration

1. Cold Starts:

Lambda functions can have a delay during initial invocations due to cold starts. To mitigate this, consider using AWS Lambda provisioned concurrency.

2. CORS Issues:

If your frontend cannot access the API, ensure that CORS is properly configured in API Gateway. You can enable CORS from the API Gateway console or using CDK.

3. Timeouts:

By default, Lambda functions have a 3-second timeout. If your NestJS application takes longer to respond, increase the timeout setting.

Architectural Considerations and Future Trends

  • Microservices with Lambda: As serverless architecture evolves, breaking your NestJS app into microservices deployed on individual Lambda functions can improve scalability and maintainability.
  • Event-Driven Architectures: AWS Lambda works well with event-driven designs, allowing you to integrate your NestJS app with services like AWS SQS, SNS, or Kinesis for asynchronous workflows.
  • Future of Serverless: The trend toward serverless and microservices architectures is expected to continue growing, making tools like NestJS and AWS Lambda a critical part of modern cloud strategies.

References

Using Lambda with API Gateway

Create a REST API with a Lambda proxy integration