02 Faas Concepts

title: FaaS Concepts for Serverless API Development weight: 12 date: 2026-06-28 lastmod: 2026-06-28 description: Understand Function-as-a-Service core concepts including stateless functions, cold starts, execution duration limits, event sources, and function lifecycle management. tags: [api-development, serverless]

FaaS (Function-as-a-Service) runs stateless functions triggered by events, with each invocation running in an isolated container, limited to 15-minute execution duration, 128MB-10GB memory, and ephemeral storage that resets between calls.

```python
# Basic AWS Lambda handler
import json

def lambda_handler(event, context):
    # event: Trigger event data (API Gateway request, S3 notification, etc.)
    # context: Runtime information (function name, remaining time, request ID)

    print(f"Function {context.function_name} invoked")
    print(f"Request ID: {context.aws_request_id}")

    # Parse API Gateway event
    http_method = event.get("httpMethod", "GET")
    path = event.get("path", "/")
    body = json.loads(event.get("body", "{}")) if event.get("body") else {}

    return {
        "statusCode": 200,
        "headers": {"Content-Type": "application/json"},
        "body": json.dumps({
            "message": f"Processed {http_method} {path}",
            "input": body
        })
    }

What's Next

Now learn about AWS Lambda setup in Building Serverless APIs.