Building Serverless APIs with AWS Lambda and API Gateway

What is Serverless?

Serverless computing allows you to build and run applications without managing servers. AWS Lambda executes your code in response to events and automatically manages the compute resources.

Setting Up AWS Lambda Function

// lambda-function.js
exports.handler = async (event) => {
    const response = {
        statusCode: 200,
        headers: {
            'Content-Type': 'application/json',
            'Access-Control-Allow-Origin': '*'
        },
        body: JSON.stringify({
            message: 'Hello from Lambda!',
            input: event
        })
    };
    return response;
};

Creating API Gateway Endpoint

Steps to create a REST API:

Create a new API in API Gateway
Create a resource (e.g., /users)
Create methods (GET, POST, etc.)
Connect methods to Lambda function
Deploy API to a stage

Lambda Function with Database

const AWS = require('aws-sdk');
const dynamodb = new AWS.DynamoDB.DocumentClient();

exports.handler = async (event) => {
    try {
        const params = {
            TableName: 'Users',
            Item: {
                id: event.requestContext.requestId,
                name: JSON.parse(event.body).name,
                email: JSON.parse(event.body).email,
                createdAt: new Date().toISOString()
            }
        };
        
        await dynamodb.put(params).promise();
        
        return {
            statusCode: 201,
            body: JSON.stringify({ message: 'User created successfully' })
        };
    } catch (error) {
        return {
            statusCode: 500,
            body: JSON.stringify({ error: error.message })
        };
    }
};

Benefits of Serverless

No Server Management: AWS handles infrastructure
Auto-scaling: Scales automatically with traffic
Cost-effective: Pay only for execution time
High Availability: Built-in fault tolerance

Best Practices