SetRequestHostHeader Filter

There are certain situation when the host header may need to be overridden. In this situation, the SetRequestHostHeader filter can replace the existing host header with a specified value. The filter takes a host parameter. The following listing configures a SetRequestHostHeader filter:

application.yml
spring:
  cloud:
    gateway:
      server:
        webmvc:
          routes:
            - id: set_request_host_header_route
              uri: http://localhost:8080
              predicates:
              - Path=/headers
              filters:
              - name: SetRequestHostHeader
                args:
                  host: example.org
GatewaySampleApplication.java
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.uri;
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.setRequestHostHeader;
import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;

@Configuration
class RouteConfiguration {

    @Bean
    public RouterFunction<ServerResponse> gatewayRouterFunctionsSetRequestHostHeader() {
        return route("set_request_host_header_route")
            .GET("/headers", http())
            .before(uri("http://localhost:8080"))
            .before(setRequestHostHeader("example.org"))
            .build();
    }
}

The SetRequestHostHeader filter replaces the value of the host header with example.org.