This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Cloud Gateway 4.1.6!

Java Routes API

Spring Cloud Gateway Server MVC uses the Spring WebMvc.fn RouterFunctions.Builder as the default way to create Routes, which are WebMvc.fn RouterFunction instances.

A RouterFunctions.Builder instance is obtained by calling RouterFunctions.route()

GatewaySampleApplication.java

import static org.springframework.web.servlet.function.RouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;

class SimpleGateway {
    @Bean
    public RouterFunction<ServerResponse> getRoute() {
        return route().GET("/get", http("https://httpbin.org")).build();
    }
}

There are methods in RouterFunctions.Builder for each HTTP methods (GET, POST, etc…) combined with a path predicate, such as /get as above. The final parameter is the HandlerFilterFunction, in this case HandlerFunctions.http(). There are overloaded methods for each HTTP method for additional RequestPredicate parameters as well as a generic route(RequestPredicate, HandlerFunction) method for general use.

Gateway MVC implementation of RouterFunctions.Builder

Some advanced filters require some metadata to be added to request attributes. To accommodate this, there is a org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions class. GatewayRouterFunctions.route(String routeId) creates a `RouterFunctions.Builder instance then adds a 'before' filter to add the routeId as request metadata.

GatewaySampleApplication.java

import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;

class SimpleGateway {
    @Bean
    public RouterFunction<ServerResponse> getRoute() {
        return route("simple_route").GET("/get", http("https://httpbin.org")).build();
    }
}

Gateway MVC Handler Functions

Various RouterFunctions.Builder methods require a HandlerFunction<ServerResponse>. To create a route that is proxied by the MVC Gateway, HandlerFunction implementations are supplied in org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions. The most basic is the http() HandlerFunction. If a URI is supplied as a parameter, that is the URI used as the downstream target for sending the HTTP requests (as seen in the example above). If no parameter is passed, the function looks for a URI in the org.springframework.cloud.gateway.server.mvc.common.MvcUtils.GATEWAY_REQUEST_URL_ATTR request attribute. This allows for dynamic targets such as load balancing to set the URI.