How to Use AWS Lambda for Serverless Functions: A Beginner’s Tutorial
AWS Lambda runs your code without servers. You upload a function, AWS handles scaling, patching, and availability, and you pay only for the milliseconds your code runs. Here’s how to build your first serverless function.
Everything starts in the AWS Console: create a function, pick a runtime, paste your code, and attach a trigger. No EC2 instances, no containers to manage.
1. Create Your First Function
Open the Lambda console, click Create function, and choose “Author from scratch.” Select a runtime, name it, and let AWS create an execution role with basic permissions. A starter handler appears automatically.
2. Understand the Handler
The handler is your entry point. It receives an event object and returns a response:
- event – input data from the trigger, like an HTTP request or file upload
- context – runtime details such as request ID and timeout
- return value – what your caller receives back
3. Connect a Trigger
Functions need something to invoke them. Add API Gateway for REST endpoints, S3 for file processing, or EventBridge for scheduled jobs. Lambda receives each event automatically.
4. Test and Deploy
Use the built-in test console with a sample event. Adjust memory and timeout — more memory also means more CPU. Then check CloudWatch Logs for output and errors.
Conclusion
Start small: one function, one trigger, one test event. Once that works, add environment variables and monitoring. The same setup scales to millions of requests without changing your workflow.
