118. Configuration

Configuration for Spring Cloud Gateway is driven by a collection of RouteDefinitionLocators.

RouteDefinitionLocator.java.

public interface RouteDefinitionLocator {
	Flux<RouteDefinition> getRouteDefinitions();
}

By default, a PropertiesRouteDefinitionLocator loads properties using Spring Boot’s @ConfigurationProperties mechanism.

The configuration examples above all use a shortcut notation that uses positional arguments rather than named ones. The two examples below are equivalent:

application.yml.

spring:
  cloud:
    gateway:
      routes:
      - id: setstatus_route
        uri: http://example.org
        filters:
        - name: SetStatus
          args:
            status: 401
      - id: setstatusshortcut_route
        uri: http://example.org
        filters:
        - SetStatus=401

For some usages of the gateway, properties will be adequate, but some production use cases will benefit from loading configuration from an external source, such as a database. Future milestone versions will have RouteDefinitionLocator implementations based off of Spring Data Repositories such as: Redis, MongoDB and Cassandra.

118.1 Fluent Java Routes API

To allow for simple configuration in Java, there is a fluent API defined in the RouteLocatorBuilder bean.

GatewaySampleApplication.java.

// static imports from GatewayFilters and RoutePredicates
@Bean
public RouteLocator customRouteLocator(RouteLocatorBuilder builder, ThrottleGatewayFilterFactory throttle) {
    return builder.routes()
            .route(r -> r.host("**.abc.org").and().path("/image/png")
                .filters(f ->
                        f.addResponseHeader("X-TestHeader", "foobar"))
                .uri("http://httpbin.org:80")
            )
            .route(r -> r.path("/image/webp")
                .filters(f ->
                        f.addResponseHeader("X-AnotherHeader", "baz"))
                .uri("http://httpbin.org:80")
            )
            .route(r -> r.order(-1)
                .host("**.throttle.org").and().path("/get")
                .filters(f -> f.filter(throttle.apply(1,
                        1,
                        10,
                        TimeUnit.SECONDS)))
                .uri("http://httpbin.org:80")
            )
            .build();
}

This style also allows for more custom predicate assertions. The predicates defined by RouteDefinitionLocator beans are combined using logical and . By using the fluent Java API, you can use the and() , or() and negate() operators on the Predicate class.

118.2 DiscoveryClient Route Definition Locator

The Gateway can be configured to create routes based on services registered with a DiscoveryClient compatible service registry.

To enable this, set spring.cloud.gateway.discovery.locator.enabled=true and make sure a DiscoveryClient implementation is on the classpath and enabled (such as Netflix Eureka, Consul or Zookeeper).