Spring Cloud Gateway: API Protection and Scalability Techniques

Spring Cloud Gateway enables efficient API management and security for scalable applications.

### Protecting and Scaling APIs with Spring Cloud Gateway
Spencer Gibb and Luke Shannon discuss the importance of **HTTP APIs** and the role of **Spring Cloud Gateway** in protecting and scaling them. They highlight the different layers of API protection, including **transport security** and **application layer security** with Spring Security and OAuth 2. The speakers also discuss various strategies for scaling APIs, such as **scaling up hardware**, **scaling out with multiple instances**, and using **Native compilation with Grow VM** for resource efficiency. Additionally, they emphasize the importance of **rate limiting** to manage traffic and protect backend services.

### Rate Limiting and Circuit Breakers in API Management
Rate limiting can be implemented using the **token bucket algorithm**, which adds tokens to a bucket at a configured interval. A demo using Bucket4J shows how to rate limit requests, with the gateway returning a **429 error** when the bucket is empty. Circuit breakers protect against cascading failures by **opening after a certain number of failures**, using a fallback method to provide **alternative responses**.

### Key Features of Gateway Resilience
The Gateway's fallback mechanism provides additional information on failed requests, helping to **determine the next steps**. The retry feature protects against instance failures by retrying failed calls, with a focus on **idempotent requests** and typically targeting **500 errors**. The "scale to zero" approach offers **cost savings** by not running instances of an application during low or no traffic periods, making it ideal for applications with **sporadic workloads**.

### Scaling Applications with Kada and Spring Cloud Gateway
Kada is installed in Kubernetes to handle app scaling from **0 to 1**, while Kubernetes manages scaling from **1 to N**. Kada's component intercepts requests and communicates with the application via **gRPC** to determine the number of instances running. The Spring team is promoting the use of **Spring Cloud Gateway** in Kubernetes, with a proof of concept to **replace Kada's component**, and the demo showcases the **installation and scaling** of a demo application.

### Scaling Teams with Open API and Spring Cloud Gateway
The commercial product offers individual services their own **Open API endpoints**, aggregating them for **easy search across the enterprise**. Spring Cloud Gateway enforces **security and manages service instances**, while also providing **distributed tracing for problem-solving**. The use of **service discovery and a central registration system** helps teams manage **dynamic distributed systems effectively**.

### Centralized Authentication and API Orchestration
The system consists of Spring Boot APIs and a React UI, with the **Gateway on port 880** playing a crucial role. The Gateway handles **authentication using Azure AD**, routing, and managing cookies and headers. The flow of authentication involves issuing a **JWT token**, which is then used by the downstream APIs to **verify authenticated sessions**.

### Simplifying API Routing and Notification Management
The React application checks for unread notifications by making a call to the notification server, using a **simple API proxy setup**. The Gateway's routing configuration **abstracts the UI layer from host details** and **eliminates cross-origin request issues**. The Gateway also provides support for **API versioning** and offers a solution for **tracking user sessions across multiple APIs** through a **unique cookie**.

### Using Spring Cloud Gateway for API Management
The speaker implemented a solution using Spring Cloud Gateway to **avoid code changes for API owners**. They used an after filter to add a Dynatrace cookie with the user's **JWT token and email**, providing a **complete view of user activity**. The speaker highlighted the benefits of the MVC Gateway's traditional servlet model with Loom virtual threads for **simpler API management**.

### Spring Cloud Gateway: Enhancing API Management and Security
* 👋 Welcome back to the Spring One at Explore event, where attendees can **join the discussion on Discord** and **ask questions after the talk**.
* 🎤 Spencer Gibb, a member of the Spring team for **10 years**, introduces the session on Spring Cloud Gateway alongside Luke Shannon, who will present a **case study later**.
* 📅 The agenda covers the **nature of APIs**, methods to **protect resources**, **decomposing monoliths**, scaling teams with **Gateway**, and Luke's **case study**.
* 🔒 API protection involves multiple layers, including **transport security with HTTPS** and **application-level security using Spring Security and OAuth 2**.
* 📈 Scaling APIs can be achieved by **scaling up** (enhancing hardware) or **scaling out** (adding instances), and techniques like **compiling to Native with GraalVM** can optimize resource use.
* ⚖ Rate limiting can manage traffic effectively, using methods like the **token bucket algorithm**, while circuit breakers prevent cascading failures by using **fallback mechanisms**.
* 🔄 The Spring Cloud Gateway also supports **retry logic for handling transient failures** and introduces the concept of **scaling to zero for cost savings** during low traffic periods.
* 🔍 Luke Shannon showcases his company's use of **Spring Cloud Gateway** for **centralized authentication, routing, and observability**, demonstrating its effectiveness in **managing APIs** within their architecture.

Scaling APIs With Spring Cloud

Spring is the most popular application development framework for Java™. 
Millions of developers use Spring to build simple, truly portable, fast and flexible JVM-based systems and applications.
Learn more about Spring at http://www.spring.io