Node.js in AWS Lambdas: Does this make sense?

Introduction

Node.js is like the Swiss Army knife of JavaScript—a versatile, event-driven powerhouse designed to juggle multiple requests with ease. It’s the go-to tool for building scalable applications that can handle just about anything you throw at them. But when you deploy Node.js in an AWS Lambda function, its multitasking prowess seems to be put on pause. Each Lambda instance handles just one request at a time, which makes you wonder: are we losing one of Node.js’s best features?

The Event Loop: Node.js’s Secret Weapon

The event loop is what makes Node.js stand out. It’s built to handle asynchronous operations like a pro, managing multiple tasks at once without breaking a sweat. This is why Node.js is often the first choice for developers building high-performance, real-time applications.

The AWS Lambda Conundrum

AWS Lambda is fantastic for running code in response to events, scaling automatically, and keeping costs down. However, with only one request processed per function instance, Node.js’s event loop doesn’t get to flex its muscles the way it would in a traditional server environment. It’s like hiring a world-class chef to make you a sandwich—sure, the sandwich will be great, but there’s so much more they could be doing.

So, Why Use Node.js in Lambdas?

Even with this apparent mismatch, there are solid reasons why Node.js remains a popular choice for AWS Lambda:

1. Asynchronous I/O Operations: Despite handling only one request at a time, Node.js still shines in managing asynchronous I/O operations within that single request. Remember that Node.js gives you access to a single thread (the event loop), but while executing async I/O operations, you are really asking Node.js to handle simultaneous requests. This is often done using multiple threads. It can juggle tasks like database queries and API calls without getting bogged down because of this, making it a smart choice even in a single-request environment.
2. Cost Efficiency: Running Lambdas is often more cost-effective than maintaining traditional servers or containers. Even if you’re not taking full advantage of Node.js’s event loop, the savings in infrastructure management and costs can more than make up for it. Personally, I have ran API loads in Lambdas that handled 10x (often much more) the number of requests than ECS Fargate, and the Lambdas were still 10% of the price. That is with warmers, too!
3. Familiar Ecosystem: JavaScript is everywhere, and Node.js is its natural server-side companion. Using Node.js in Lambdas allows developers to leverage their existing skills and the vast array of NPM packages, reducing the time spent on learning and integrating new tools.
4. Rapid Prototyping: Node.js’s lightweight nature and extensive library support make it perfect for quickly spinning up serverless functions. AWS Lambda’s deployment and scaling capabilities complement this nicely, making it easier to go from concept to production without heavy lifting.
5. Improved Context Management: The introduction of AsyncLocalStorage (Thread Local) in Node.js has made it easier to manage request-specific data across asynchronous operations. Prior to AsynLocalStorage, AWS Lambdas were a great choice if you needed high levels of observability by including request parameters in every log message. This is because you could use the global object as your thread local to get access to the parameters without passing it through the entire business logic layer.

Conclusion

While using Node.js in AWS Lambdas might seem like a case of mismatched potential—like driving a sports car in bumper-to-bumper traffic—there are plenty of reasons why it’s still a great choice. From its asynchronous I/O capabilities to the familiar ecosystem and cost savings, Node.js brings a lot to the table, even in a Lambda environment.

In the end, it might not be the perfect match, but it’s one that works surprisingly well for many use cases.