What is the purpose of SpringCloud Gateway?

Spring Cloud Gateway is an API gateway built on Spring Framework 5, Spring Boot 2, and Project Reactor, designed for creating gateway services in a microservices architecture. It serves as the entry point for all requests in the microservices architecture, responsible for routing requests to the appropriate microservice instances and providing features such as load balancing, circuit breaking, and rate limiting.

Specific functions include:

1. Routing forwarding: Spring Cloud Gateway can forward requests to the corresponding microservice instances based on the request path and other conditions. It supports routing based on path, Host, Header, request parameters, and other conditions.
2. Load balancing: The Gateway can achieve load balancing for microservices by integrating with a service registry center like Eureka. It can distribute requests to different microservice instances based on a load balancing strategy.
3. Circuit breaking and degradation: The Gateway supports circuit breaker mode, which can melt when a microservice fails or times out, to prevent the fault from spreading. It also supports degradation strategies, where when a microservice fails, it can gracefully degrade by returning default values or other alternative solutions.
4. Throttling: By configuring throttling rules, a gateway can restrict the number of concurrent requests or request counts to a particular microservice, preventing it from being overloaded.
5. Security authentication: Gateway can integrate frameworks such as Spring Security to provide functions for security authentication and access control, protecting microservices from unauthorized access.

In summary, Spring Cloud Gateway acts as the gateway in a microservices architecture, offering a unified entry point and common gateway features to help developers build stable, reliable, and secure microservices architecture.