Building a Spring Cloud Gateway with Dynamic Routing via Nacos and Implementing Authentication Filters

Introduction: The author, a senior architect, explains how to use Spring Cloud Gateway to build a gateway service and achieve dynamic routing.

Setup

Uses Spring Boot 2.1 and adds dependencies spring-cloud-gateway-core and commons-lang3 . Shows Maven parent and dependency snippets.

Route Configuration

Defines a static route in application.yml with server port 8080, route id demo-server , uri http://localhost:8081 , predicates Path=/demo-server/** and filter StripPrefix=1 .

Dynamic Routing with Nacos

Describes deploying Nacos, storing route definitions as JSON (dataId “routes”), and listening to changes via @NacosConfigListener . Provides JSON example and equivalent YAML.

Implementation

Shows a Spring component NacosDynamicRouteService that clears old routes, parses new definitions, adds them with RouteDefinitionWriter , and publishes a RefreshRoutesEvent .

Filter Development

Explains creating a GlobalFilter that implements Ordered . The filter extracts a token from header, query or cookie, validates it against Redis, adds user_id to the request, refreshes token expiration, and rejects unauthenticated requests with 401.

Redis Configuration

Provides Maven dependency for spring-boot-starter-data-redis-reactive and sample Redis properties.

Finally, the article summarizes that Gateway can handle routing via configuration, Nacos enables dynamic updates, and custom filters provide authentication.