AWS Lambda for Beginners

Step 1 — Create a Function from Scratch

1. Open the Lambda console → Create function.
2. Choose Author from scratch.
3. Name it (for example hello-demo), pick a runtime (Node.js or Python), and create a new execution role with basic permissions.

Step 2 — Return a Simple Message

Use the inline editor so the handler returns JSON text.

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

How It Works

1. Deploy / Save so the latest code is what Lambda runs.
2. statusCode + body are common when API Gateway will call this function later.

Step 3 — Create a Test Event

1. Choose Test, create a hello event (empty JSON {} is fine).
2. Run the test and confirm the response shows your message.
3. Open CloudWatch logs from the monitor tab if something fails.

Step 4 — Put API Gateway in Front

1. Follow Amazon API Gateway to create an HTTP API.
2. Integrate a route (for example GET /hello) with this Lambda function.
3. Allow API Gateway to invoke Lambda when the console prompts for permission.
4. Call the invoke URL in a browser or with curl.