Serverless

Build and run applications and services without managing servers

Embrace Serverless: Building Applications with AWS Lambda and API Gateway

In the not-so-distant past, deploying a web application or service meant provisioning servers, installing operating systems, configuring web servers, managing patches, and constantly worrying about scaling to handle traffic spikes. I have personally spent 2 sleepless days to fix server issue after deployment before containerization was a thing.

This infrastructure management was often complex, time-consuming, and costly.

Enter Serverless Architecture. This paradigm represents a fundamental shift in how we build and deploy applications, allowing developers to focus almost entirely on writing code while the cloud provider handles the underlying infrastructure. You don't provision, manage, or scale servers; you just write code, and it runs when needed.

On Amazon Web Services (AWS), two services are cornerstones of building serverless applications, particularly backend APIs: AWS Lambda and AWS API Gateway. Let's dive into what Serverless means and how this powerful duo works together.

What is Serverless Architecture?

The term "serverless" is a bit of a misnomer – there are still servers involved, but you, the developer or operator, don't have to think about them. Serverless computing allows you to run code without provisioning or managing servers. Your cloud provider automatically handles the scaling, patching, and maintenance of the infrastructure.

Key characteristics of serverless include:

• No Server Management: You don't deal with EC2 instances, operating systems, or scaling groups.

• Event-Driven: Your code (typically packaged as functions) is triggered by various events (HTTP requests, database changes, file uploads, scheduled events, etc.).

• Automatic Scaling: The provider automatically scales your application in response to demand, from zero up to massive traffic volumes.

• Pay-per-Usage: You typically only pay for the compute time consumed or the number of requests handled, rather than paying for always-on servers. This could be heaven-sent or hell-unleashed experience for you, 50$ on sunny months and WTF 600$ on error ones.

AWS Lambda: The Serverless Compute Engine

At the core of AWS's serverless offering is AWS Lambda. This is Amazon's Function as a Service (FaaS). You upload your code (in various languages like Python, Node.js, Java, Go, etc.), and Lambda executes it when triggered by a configured event. Alternatives are Azure Functions, Google Cloud Functions, you should consider which one suits best for your application before deploying the app.

Think of Lambda as the engine that runs your business logic. You define a function that does a specific task (e.g., process an order, resize an image, handle an API request), and Lambda ensures that function runs whenever the trigger event occurs. You don't manage the underlying servers, the operating system, or the language runtime environment; Lambda handles all of that. The major appeal is that you only pay for the milliseconds your function is executing.

AWS API Gateway: The Managed API Front Door

While Lambda runs your code, you need a way for external clients (like web browsers, mobile apps, or other services) to actually access that code, especially when building APIs. This is where AWS API Gateway comes in.

API Gateway is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale. It acts as the "front door" for ¹ your applications, routing incoming API requests to your backend services.

In a serverless context, API Gateway is commonly used to expose Lambda functions as RESTful APIs or WebSocket APIs. It handles receiving the HTTP request, performing authentication or authorization if needed, potentially transforming the request data, and then triggering the appropriate Lambda function. It then receives the response from Lambda and sends it back to the client.

The Power Duo: Lambda + API Gateway for Serverless Backends

The combination of AWS Lambda and API Gateway is a prevalent pattern for building serverless backend APIs. Here's the typical flow:

1. A client (e.g., a web browser) sends an HTTP request to your API endpoint managed by API Gateway.

2. API Gateway receives the request. Based on the API configuration (path, HTTP method), it knows which backend resource to invoke.

3. API Gateway triggers the corresponding AWS Lambda function, passing the request details (headers, body, query parameters) as input.

4. The Lambda function executes your code, performs the necessary logic (e.g., interacts with a database like DynamoDB, processes data).

5. The Lambda function returns a response (e.g., JSON data) to API Gateway.

6. API Gateway receives the response and sends it back to the client.

This architecture provides immense benefits:

• Automatic Scaling: API Gateway can handle millions of requests, and Lambda scales automatically to run as many instances of your function as needed to meet demand.

• Cost-Effectiveness: You pay per API call and per Lambda function execution time. This is incredibly cost-efficient for variable workloads or applications with idle periods.

• Reduced Operational Burden: No servers to manage means less time spent on maintenance and more time focused on building features.

• Faster Time to Market: Developers can quickly deploy and update individual API endpoints (functions) without redeploying an entire server.

You could probably throw in AWS CloudFront CDN (Content Delivery Network) to achieve consistence with same provider benefits. Personally, we use CloudFlare to utilize their Workers and Pages features along with their CDN.

Considerations

While powerful, the serverless model isn't a silver bullet. Potential considerations include:

• Cold Starts: The first time a Lambda function is invoked after a period of inactivity, it might experience a brief delay as the execution environment spins up.

• Complexity of Many Functions: Managing a large number of small, independent functions can introduce its own complexity.

• Monitoring and Debugging: Different tools and approaches are often needed compared to traditional server-based applications.

• Vendor Lock-in: Building heavily on AWS services like Lambda and API Gateway creates a dependency on the AWS ecosystem.

Conclusion

Serverless architecture, enabled by services like AWS Lambda and API Gateway, represents a significant evolution in cloud computing. By abstracting away server management, it allows developers to increase their agility, optimize costs, and build applications that can automatically scale to meet unpredictable demand.

For building modern, scalable, and efficient backend APIs, the combination of AWS Lambda's on-demand compute and API Gateway's managed entry point is a compelling and widely adopted pattern, fundamentally changing how we think about deploying code in the cloud.