Scenario

Your team needs a simple Lambda function for a greeting microservice.

Task

1. Create a Lambda function named hello-function that:

   • Takes a name field from the event input
   • Returns the string Hello <name> (e.g. input {"name": "World"} returns "Hello World")
   • Uses the pre-created IAM role lambda-execution-role

2. Invoke the function with {"name": "World"} and verify it returns "Hello World"

Note: You can use Python (python) or Node.js (nodejs) as the runtime. You can use either the AWS Management Console or AWS CLI to complete this task.

Step 1: Write the function code

Create lambda_function.py:

def lambda_handler(event, context):
    name = event['name']
    return f"Hello {name}"

Step 2: Package the function

zip function.zip lambda_function.py

Step 3: Get the IAM role ARN

ROLE_ARN=$(aws iam get-role --role-name lambda-execution-role --query 'Role.Arn' --output text)

Step 4: Create the Lambda function

aws lambda create-function \
  --function-name hello-function \
  --runtime python3.13 \
  --role "$ROLE_ARN" \
  --handler lambda_function.lambda_handler \
  --zip-file fileb://function.zip

The --handler format is filename.function_name — so lambda_function.handler means the handler function in lambda_function.py.

Step 5: Invoke the function

aws lambda invoke \
  --function-name hello-function \
  --cli-binary-format raw-in-base64-out \
  --payload '{"name": "World"}' \
  output.txt

cat output.txt

Should output "Hello World".