Welcome to the foundational step of building serverless applications on AWS: creating your first AWS Lambda function. Lambda allows you to run code without provisioning or managing servers. This guide will walk you through the process, from understanding the basics to deploying a simple function.

AWS Lambda is a compute service that lets you run code for virtually any type of application or backend service – all with zero administration. You pay only for the compute time you consume; there is no charge when your code is not running. Simply upload your code and configure it to trigger from an event source, such as an API Gateway endpoint, an S3 bucket event, or a scheduled event.

Before you begin, ensure you have an AWS account. If you don't have one, you can sign up for a free tier account. Familiarity with basic programming concepts is helpful, though we'll use a simple example.

Let's create a simple 'Hello World' Lambda function using the AWS Management Console.

Log in to your AWS Management Console. In the search bar, type 'Lambda' and select 'Lambda' from the services list. This will take you to the AWS Lambda dashboard.

On the Lambda dashboard, click the 'Create function' button. You'll see several options for creating a function.

For this tutorial, select 'Author from scratch'.

You'll need to provide the following information:

• Function name: Give your function a descriptive name (e.g.,
  code

  CopyEdit

  my-first-lambda-function

  ).
• Runtime: Choose a programming language for your function. For this example, we'll select 'Node.js 18.x' (or a recent version).
• Architecture: Keep the default 'x86_64'.
• Permissions: For a new function, you'll need to create a new role with basic Lambda permissions. This role allows Lambda to write logs to CloudWatch. Select 'Create a new role with basic Lambda permissions'.

Click the 'Create function' button at the bottom of the page. AWS will provision the necessary resources and create your function.

Once your function is created, you'll be taken to its configuration page. Scroll down to the 'Code' tab. You'll see a default code snippet for the runtime you selected. For Node.js, it typically looks like this:

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

This code defines a handler function that takes an

event

async

To test your function, click the 'Test' tab above the code editor. You'll need to configure a test event. Click 'Configure test event'. Select 'hello-world' from the event template dropdown, or create a custom JSON event. Give your test event a name (e.g.,

MyTestEvent

Now, click the 'Test' button. You should see 'Execution results: Succeeded' and the 'Response' section will show

"Hello from Lambda!"

If you make any changes to your code, remember to click the 'Deploy' button above the code editor to save and apply your modifications.

Congratulations! You've successfully created and tested your first AWS Lambda function. From here, you can explore triggering your function with different event sources like API Gateway for creating serverless APIs, S3 for processing file uploads, or CloudWatch Events for scheduled tasks.