SetResponseHeader Filter

The SetResponseHeader filter takes name and value parameters. The following listing configures a SetResponseHeader filter:

application.yml
spring:
  cloud:
    gateway:
      mvc:
        routes:
        - id: setresponseheader_route
          uri: https://example.org
          filters:
          - SetResponseHeader=X-Response-Red, Blue
GatewaySampleApplication.java
import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFunctions.setResponseHeader;
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> gatewayRouterFunctionsSetResponseHeader() {
        return route("addresponseheader")
                .GET("/anything/addresheader", http("https://example.org"))
                .after(setResponseHeader("X-Response-Red", "Blue"))
            .build();
    }
}

This GatewayFilter replaces (rather than adding) all headers with the given name. So, if the downstream server responded with X-Response-Red:1234, it will be replaced with X-Response-Red:Blue, which is what the gateway client would receive.

SetResponseHeader is aware of URI variables used to match a path or host. URI variables may be used in the value and will be expanded at runtime. The following example configures an SetResponseHeader filter that uses a variable:

application.yml
spring:
  cloud:
    gateway:
      routes:
      - id: setresponseheader_route
        uri: https://example.org
        predicates:
        - Host: {segment}.myhost.org
        filters:
        - SetResponseHeader=foo, bar-{segment}
GatewaySampleApplication.java
import static org.springframework.cloud.gateway.server.mvc.filter.AfterFilterFunctions.setResponseHeader;
import static org.springframework.cloud.gateway.server.mvc.handler.GatewayRouterFunctions.route;
import static org.springframework.cloud.gateway.server.mvc.handler.HandlerFunctions.http;
import static org.springframework.cloud.gateway.server.mvc.predicate.GatewayRequestPredicates.host;

@Configuration
class RouteConfiguration {

    @Bean
    public RouterFunction<ServerResponse> gatewayRouterFunctionsSetResponseHeader() {
		return route("add_response_header_route")
				.route(host("{segment}.myhost.org"), http("https://example.org"))
				.after(setResponseHeader("foo", "bar-{segment}"))
				.build();
    }
}