Hello Lambda (AWS)

AWS Lambda • CloudWatch Logs • Serverless Basics

Summary

Project Overview

This project is a simple introduction to AWS Lambda. A small Python function was created and ran using a test event from the AWS console.

The goal was to understand three key things:

• How Lambda runs code on demand
• How a request goes into a function and a response comes out
• How AWS logs what happens using CloudWatch

Even though the function is small, it follows the same pattern used in real applications: something triggers the function, the code runs, and AWS records what happened.

Architecture

This project uses a very simple serverless setup. A test event is sent from the AWS console to Lambda. Lambda runs the Python function, returns a response, and CloudWatch Logs records the execution details.

User (Test Event in AWS Console)
        ↓
AWS Lambda (Python Function)
        ↓
Response Returned to Console
        ↓
CloudWatch Logs (Execution Logs)

Deployment and Configuration

The Lambda function was created in the AWS console using Python 3.11. The function name used for this lab was KickstartHelloLambda.

The code was added in the inline editor and then deployed.

import json

def lambda_handler(event, context):
    return {
        "statusCode": 200,
        "headers": {"Content-Type": "application/json"},
        "body": json.dumps({
            "message": "Hello from Lambda",
            "requestId": context.aws_request_id
        })
    }

This function returns a simple JSON response showing a message and the AWS request ID for that run.

Request and Response

The test event used was:

{}

This is an empty request. It was passed into the function as the event. Since the function didn’t need any input, this was enough to run it.

When the function runs, AWS effectively calls:

lambda_handler({}, context)

The function then returns a response back to the console.

Execution Result

The function was run using a synchronous invocation, which means the result is returned immediately in the console.

If it was asynchronous, AWS would run the function in the background and you would not see the result straight away.

Lambda Test Result (Succeeded)

Example: successful Lambda test showing Status: Succeeded and the function response.

The result showed the function ran successfully with a 200 status code. This means everything worked correctly.

CloudWatch Logs

CloudWatch Logs stores what happens when your Lambda runs.

You can access logs from:

• Lambda → Monitor → View logs in CloudWatch
• Or directly in CloudWatch under the log group:

/aws/lambda/KickstartHelloLambda

CloudWatch Log Example

Example: invocation log showing START, END, and REPORT entries for the Lambda function.

The logs show when the function started, ended, and how long it took to run.

This is useful for checking if your function worked and for debugging if something goes wrong.

Skills Demonstrated

• Created an AWS Lambda function using Python 3.11
• Used the AWS console to deploy and test a function
• Ran a Lambda function with a JSON test event
• Understood the basics of request and response handling
• Used synchronous execution to view results immediately
• Located and reviewed logs in CloudWatch
• Built a beginner-level understanding of serverless computing

Key Takeaways

• Lambda runs code only when triggered
• A request goes in, and a response comes out
• CloudWatch Logs shows what happened during execution
• Synchronous = instant result, Asynchronous = background execution