AWS Compute and Serverless Services Overview

Exam Tip: If a question asks about running containers without managing servers, the answer is Fargate. If it mentions Kubernetes, the answer is EKS.

Serverless and Event-Driven Computing

"Serverless" does not mean there are no servers; it means the servers are invisible to the developer. You simply deploy your code, and AWS handles all provisioning, scaling, and maintenance. This model is highly cost-effective because billing is based on actual usage rather than idle capacity.

AWS Lambda (Function as a Service)

AWS Lambda is the premier Function as a Service (FaaS) offering. You upload a piece of code (a "function"), and it executes in response to specific triggers, such as an S3 upload or an API request.

Lambda has specific constraints and a unique pricing model:

• Execution Limit: A single function can run for a maximum of 15 minutes.
• Scaling: It scales automatically in response to incoming request volume.
• Pricing: You are billed based on the number of invocations and the product of the duration and the RAM provisioned.

Mathematically, the cost component for duration can be viewed as: $\text{Cost} \propto \text{Invocations} \times (\text{Duration} \times \text{RAM Provisioned})$

Amazon API Gateway

To make your Lambda functions accessible to the internet, you often use Amazon API Gateway. This managed service allows you to create, publish, and secure REST, HTTP, and WebSocket APIs. It acts as the "front door," handling tasks like authentication, request throttling, and versioning, effectively turning your Lambda functions into a complete serverless backend.

Specialized Compute Workloads

Not every workload fits the short-lived, event-driven nature of Lambda or the orchestration requirements of containers. AWS provides specialized services for different patterns:

AWS Batch is designed for large-scale, resource-heavy, or long-running batch jobs. Unlike Lambda, which is designed for quick bursts of activity, Batch can run jobs across managed EC2 or Spot instances without strict time limits, making it perfect for data processing or scientific simulations.

Amazon Lightsail is the "easy button" for simple applications. It provides virtual servers, storage, and databases with a predictable monthly price. It is intended for users—such as those deploying a simple WordPress site or a small blog—who want to avoid the complexity of configuring Virtual Private Clouds (VPCs) or Load Balancers.

Summary Table of Compute Services

By matching your application's architecture—whether it is a complex microservices web via EKS or a simple automated task via Lambda—to the appropriate AWS compute service, you can optimize both performance and cost.