API Gateway, Cognito and Node.js Lambdas

By Matthew Casperson

AWS is one of the most popular cloud platforms available today, with services offering high performance and scale across the globe. However, integrating the various services with one another is not quite as easy as the brochure would have you believe.

This book steps you through the process of configuring a Lambda instance running a Node.js application, calling it from the web via an API Gateway instance, and securing the stack with Cognito user authentication.

• Language: English
• Publisher: Publishdrive
• Release date: Jan 1, 2020

Book preview

Matthew Casperosn © 2020

Table of contents

Welcome

The sample Node.js application

The Lambda instance

The Cognito user pool

The API Gateway instance

The sample web application

Hosting web apps in S3

Verifying the stack

Welcome

Technologies like microservices and serverless platforms have become popular as applications become more complex, with more developers contributing to codebases that are deployed with increasing frequency. By breaking down the functionality of a complex system into discreet applications and utilizing cloud services to host and scale those applications without having to provision the underlying hardware, developers can maintain a high velocity without sacrificing quality.

Limiting the functionality of any given microservice is key to maintaining this velocity, as it limits the scope of any changes and makes deployments or rollbacks more manageable. This also implies that cross-cutting functionality like network routing and security is best left to dedicated infrastructure rather than reimplemented with each microservice.

In AWS, Lambda, Cognito, and API Gateway services provide this cross-cutting functionality.

Hosting code in an AWS Lambda allows microservice applications to be deployed, executed and scaled without ever having to worry about the underlying hardware or operating system.

AWS Cognito then provides a service for securely managing and authenticating users, removing the need to reimplement user management systems.

Finally, API Gateway takes care of exposing your code via the web, tying together the security layer provided by Cognito, and passing traffic to and from Lambdas.

This guide describes the process of creating a Cognito user pool to manage our users, deploying a simple Node.js application to Lambda, integrating all these systems with API Gateway, and consuming the resulting endpoint from a simple JavaScript web application.

The sample Node.js application

The base layer of our infrastructure stack is the Lambda. Lambdas are typically small applications that execute relatively quickly in a disposable environment. Once code is deployed to a Lambda, there is no need to manage the underlying operating system or hardware. This is where the term serverless comes from, as the developer is no longer responsible for how and where the code runs.

Lambdas can execute code written in a variety of languages, and for this guide, we create a simple Node.js Lambda.

The source code