Using AWS Lambda for Serverless Applications

Tutorial 2 of 5

Introduction

This tutorial aims to guide you through the process of using AWS Lambda, a popular serverless computing service that runs your code in response to events and automatically manages the underlying compute resources for you. You will learn how to create, deploy, and manage Lambda functions.

Prerequisites:

Basic understanding of AWS.
Basic knowledge about Node.js and JavaScript.
AWS account setup.

Step-by-Step Guide

1. Setup

First, sign into your AWS account and navigate to the AWS Lambda service. Click on the 'Create function' button.

2. Function Configuration

On the next page, you'll need to fill out the following details:

Function name: Give a unique name to your function.
Runtime: Select the language of your code. For this tutorial, we'll use Node.js.
Role: Choose 'Create a new role from one or more templates'. Fill the Role name and select 'Basic Edge Lambda permissions' from the Policy templates.

Click 'Create function' to proceed.

3. Function Code

You are now in the editor window where you can write or paste your code. For this tutorial, we'll use a simple Node.js function:

exports.handler = async (event) => {
    const response = {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
    return response;
};

Click 'Save' when you're done.

Code Examples

Example 1: Simple Lambda Function

exports.handler = async (event) => {
    // The input event is an object that contains all the information about the current event
    // The function returns a response object
    const response = {
        statusCode: 200, // HTTP Status code
        body: JSON.stringify('Hello from Lambda!'), // Response body
    };
    return response; // The function returns the response object
};

When this function is invoked, it will return a response with HTTP status 200 and a body containing the string 'Hello from Lambda!'.

Summary

In this tutorial, you learned how to create and deploy a function in AWS Lambda. You have also learned how to navigate the AWS Lambda console, how to configure a function, and how to write a simple Lambda function.

Next, you might want to learn more about how to use AWS Lambda with other AWS services, like API Gateway, to create larger applications. You can also look into error handling, logging, and monitoring for your Lambda functions.

Practice Exercises

Exercise 1: Create a Lambda function that returns a simple HTML page.

Exercise 2: Create a Lambda function that takes two numbers as input and returns their sum.

Solution and Explanation:

For the first exercise, the code would look something like this:

exports.handler = async (event) => {
    const response = {
        statusCode: 200,
        headers: {
            'Content-Type': 'text/html',
        },
        body: `<html><body><h1>Hello from Lambda!</h1></body></html>`,
    };
    return response;
};

For the second exercise, you'll need to parse the input from the event object:

exports.handler = async (event) => {
    const num1 = parseInt(event.num1);
    const num2 = parseInt(event.num2);
    const sum = num1 + num2;

    const response = {
        statusCode: 200,
        body: JSON.stringify(`The sum is ${sum}`),
    };
    return response;
};

For further practice, try creating Lambda functions that interact with other AWS services, like DynamoDB or S3.