Going Serverless: Lambda, API Gateway, and DynamoDB

Serverless computing lets you run code without provisioning or managing servers. AWS Lambda, combined with API Gateway and DynamoDB, gives you a powerful stack for building APIs that scale automatically and cost next to nothing at low traffic.

The Architecture

Client → API Gateway → Lambda → DynamoDB
                         ↓
                    CloudWatch Logs

API Gateway handles HTTP routing and request validation. Lambda runs your business logic. DynamoDB provides a fast, scalable NoSQL database. CloudWatch captures logs and metrics from every invocation.

Lambda with Terraform

resource "aws_lambda_function" "api" {
  function_name = "blog-api"
  runtime       = "python3.12"
  handler       = "handler.main"
  filename      = "lambda.zip"
  role          = aws_iam_role.lambda_exec.arn

  environment {
    variables = {
      TABLE_NAME = aws_dynamodb_table.posts.name
    }
  }
}

Cost Profile

The beauty of serverless is the pay-per-use model. Lambda charges per request and compute time. DynamoDB on-demand mode charges per read/write. For a blog API handling a few thousand requests per day, you're looking at pennies. Compare that to running an EC2 instance 24/7 — the savings are dramatic for bursty or low-traffic workloads.

When Not to Go Serverless

Serverless isn't a silver bullet. Cold starts can add latency to infrequent requests. Long-running processes (over 15 minutes) don't fit Lambda's execution model. And if you have steady, predictable high traffic, a container-based approach might be more cost-effective. Choose the right tool for the job.