API Gateway - AWS Study Guide (v2.0)

Learning Objectives

Understand the purpose and benefits of Amazon API Gateway as a secure front door for applications.

Comprehend core concepts such as API stages, stage variables, Lambda versions, and aliases for managing API configurations.

Learn to implement stage deployments to manage different API environments (dev, uat, prod) and configurations.

Understand and implement canary deployments for gradual, risk-mitigated rollouts of new API versions to production.

Identify how API Gateway integrates with other AWS services like Lambda, DynamoDB, S3, CloudFront, and Route 53.

Recognize key security and monitoring capabilities for API Gateway, including WAF integration and CloudWatch.

Understand the technical limitations of API Gateway, such as timeout limits.

Be aware of API Gateway's role in various architecture patterns and exam-relevant scenarios.

Introduction to Amazon API Gateway

Amazon API Gateway serves as a critical interface for modern cloud applications, facilitating secure and scalable communication between clients and backend services.

Amazon API Gateway is a vital AWS service for exposing backend services, such as Lambda functions, as RESTful APIs. It acts as a secure front door for applications to access data, business logic, or functionality from back-end services. It creates a simple, flexible, fully managed, pay-as-you-go service that handles all aspects of creating and operating a robust API or application programming interface for application backends. When upgrading an API to a new version (e.g., V2) that might alter data architecture or parameters, overwriting the existing version (V1) can lead to errors for consumers still using the older version. To prevent operational disruption and ensure backward compatibility, V1 and V2 must coexist for a period. API Gateway’s stage deployments and canary deployments are the primary mechanisms to achieve this.

API Gateway integrates seamlessly with various AWS services to build robust applications. It can trigger AWS Lambda functions, retrieve data from Amazon S3 or RDS instances, and manage requests in conjunction with Route 53 and CloudFront. For complex applications, it can be combined with DynamoDB for a serverless backend.

API Gateway Core Concepts

Understanding the fundamental building blocks of API Gateway is crucial for effective API management and deployment.

API Gateway Deployment Strategies

API Gateway provides robust deployment strategies to manage API updates with confidence, ensuring backward compatibility and minimizing disruption.

API Gateway Types

API Gateway supports different API types catering to various communication patterns between clients and backend services.

API Gateway Security and Networking

API Gateway offers robust security features and integrates with AWS networking services to ensure private and secure access to your APIs.

API Gateway Implementation Workflow (Visitor Counter Demo)

procedure

This section outlines a typical workflow for implementing a serverless visitor counter using API Gateway, AWS Lambda, and DynamoDB, based on practical demo steps.

API Gateway Limitations and Best Practices

Adhering to best practices and understanding service limitations is vital for operating reliable and performant APIs on AWS.

Exam Tips

Anytime the exam talks about creating or managing an API, think API Gateway. (Source 4)

For custom built applications requiring API interaction, API Gateway is the recommended AWS service. (Source 4)

API Gateway can be fronted with a Web Application Firewall (WAF) for DDoS protection and other security measures. (Source 4)

API Gateway supports versioning of your API. (Source 4)

Using API Gateway helps prevent baking credentials into your code. (Source 4)

AWS Lambda + API Gateway requires significant rewriting into serverless functions, which might not be suitable if the primary goal is preserving most existing code from a monolithic application. (Source 5)

Glossary

Stage

A deployment of your API in API Gateway, often named to reflect different environments (e.g., dev, uat, prod).

Stage Variables

Key-value pairs in API Gateway that allow managing configurations and parameters that vary across different API stages, similar to environment variables.

Lambda Version

An immutable snapshot of a Lambda function’s code at a specific point in time.

Lambda Alias

A pointer to a specific Lambda function version, providing a stable endpoint that can be updated to point to a new version.

Canary Deployment

A strategy for gradually rolling out new software versions to a small subset of users before a full release, allowing real-world testing and validation with live traffic.

REST API

An API type in API Gateway that receives messages from a client, forwards them to a backend resource, and forwards responses back to the client. Supports HTTP methods like GET, POST, PUT, DELETE.

Web Socket API

An API type in API Gateway that supports two-way communication between client applications and the backend, allowing the backend to send independent callback messages to connected clients.

HTTP API

A simpler, faster, and more cost-effective type of API Gateway for building RESTful APIs compared to REST APIs, optimized for low-latency and high-performance use cases.

Lambda Authorizer

A Lambda function used by API Gateway to implement custom authorization logic, validating tokens or requests and returning an IAM policy to control access to API methods.

Key Takeaways

API Gateway is central to exposing backend services as APIs, with stage and canary deployments being key to managing versions and transitions smoothly. (Source 1)

API Gateway ensures backward compatibility during API updates and minimizes disruption by allowing multiple versions to coexist. (Source 2)

API Gateway acts as a secure and fully managed 'front door' for applications, integrating well with Lambda, DynamoDB, S3, and CloudFront. (Source 4)

Security is paramount: use WAF for protection and adhere to the principle of least privilege for IAM roles. (Source 4, 10)

Private connectivity to API Gateway from on-premises uses Direct Connect and VPC Endpoints. (Source 7)