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Getting Started with AWS Lambda

AWS Lambda is a serverless compute service that runs your code in response to events without managing servers. Here’s a beginner-friendly step-by-step guide to creating, deploying, and using your first Lambda function. This is based on the official AWS documentation.

Prerequisites

• An active AWS account. Sign up at aws.amazon.com if you don’t have one.
• Basic familiarity with a programming language like Node.js or Python (Lambda supports many runtimes).

Step 1: Create a Lambda Function

1. Log in to the AWS Management Console and navigate to the Lambda service (search for “Lambda” in the services menu).
2. On the Functions page, click Create function.
3. Choose Author from scratch.
4. Enter a Function name (e.g., my-first-function).
5. Select a Runtime (e.g., Node.js 22.x or Python 3.13).
6. Leave the default architecture (x86_64) and click Create function.

This automatically creates an execution role (an IAM role) with basic permissions, like writing logs to Amazon CloudWatch.

Step 2: Write Your Code

In the Lambda console’s code editor (under the Code tab), replace the default “Hello World” code with something simple. Here’s an example that calculates the area of a rectangle based on input JSON with length and width keys.

• Node.js example:

  exports.handler = async (event) => {
    const length = event.length;
    const width = event.width;
    const area = length * width;
    console.log(`The area is ${area}`);
    console.log('Log group: /aws/lambda/' + process.env.AWS_LAMBDA_FUNCTION_NAME);
    return { area: area };
  };
  

• Python example:

  import json
  
  def lambda_handler(event, context):
    length = event['length']
    width = event['width']
    area = length * width
    print(f"The area is {area}")
    print(f"Log group: /aws/lambda/{context.function_name}")
    return {
        'statusCode': 200,
        'body': json.dumps({'area': area})
    }
  

Save the changes—deployment happens automatically for interpreted languages.

For compiled languages (e.g., Java), create a deployment package locally and upload it via the console or AWS CLI.

Step 3: Test Your Function

1. In the Test tab, click Create new test event.
2. Name it (e.g., test-area-calc).
3. Paste sample JSON input:

   {
     "length": 6,
     "width": 7
   }
   

4. Save and click Test.

View results in the Execution results section (e.g., {"area": 42}). Check logs in CloudWatch for details like duration and memory usage.

Step 4: Invoke and Monitor

• Manual invocation: Use the console’s Test button or AWS CLI: aws lambda invoke --function-name my-first-function output.json.
• Event-driven invocation: Connect triggers like API Gateway, S3 buckets, or DynamoDB streams. Go to the Configuration > Triggers tab to add them.
• Logs: Automatically sent to CloudWatch Logs. View at console.aws.amazon.com/cloudwatch/home#logsV2:log-groups under /aws/lambda/your-function-name.

Key concepts:

• Event sources/triggers: Services (e.g., S3 upload) that invoke your function with event data (JSON payload).
• Handler: The entry point (e.g., index.handler for Node.js) that processes the event.

Step 5: Clean Up (Optional)

Delete the function via the console: Actions > Delete. Also remove associated logs and IAM roles to avoid charges.

Tips

• Start with the free tier (1M requests/month).
• Use AWS SAM or Serverless Framework for advanced deployments.
• For production, configure environment variables, layers, and VPC settings in the Configuration tab.

Create your first Lambda function

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