Your First AWS Lambda Function in 20 Minutes

Lambda is the simplest cloud compute. The 20 minutes get you from zero to a callable function.

Step 1: Write the function

def handler(event, context):
    return {"statusCode": 200, "body": "hello"}

Save as app.py.

Step 2: Deploy via SAM

• Install SAM CLI; create a SAM template.yaml referencing app.py.
• sam build && sam deploy --guided, deploys the function + API Gateway.

Step 3: Invoke

curl https://<your-api-url>, should return ‘hello.’

Function executed; logs in CloudWatch.

Step 4: Logs and monitoring

CloudWatch Logs: every invocation logged.

CloudWatch Metrics: invocation count, duration, errors.

Add custom metrics with boto3.

Antipatterns

• Lambda without timeout config. Default 3s; many use cases need more.
• Hard-coding secrets. Use Secrets Manager.
• Default memory size. Tune for your workload.

What to do this week

Three moves. (1) Run the tutorial end-to-end on your own laptop / sandbox. (2) Apply the pattern to one production workload. (3) Document the variations you needed; share with the team.