FallbackHeaders 过滤器

FallbackHeaders 工厂允许您将 Spring Cloud CircuitBreaker 执行异常的详细信息添加到转发到外部应用中 fallbackUri 的请求头中,如下所示:

application.yml
spring:
  cloud:
    gateway:
      mvc:
        routes:
        - id: ingredients
          uri: lb://ingredients
          predicates:
          - Path=/ingredients/**
          filters:
          - name: CircuitBreaker
            args:
              name: fetchIngredients
              fallbackUri: forward:/fallback
        - id: ingredients-fallback
          uri: http://localhost:9994
          predicates:
          - Path=/fallback
          filters:
          - name: FallbackHeaders
            args:
              executionExceptionTypeHeaderName: Test-Header
GatewaySampleApplication.java
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.fallbackHeaders;
import static org.springframework.cloud.gateway.server.mvc.filter.BeforeFilterFunctions.uri;
import static org.springframework.cloud.gateway.server.mvc.filter.CircuitBreakerFilterFunctions.circuitBreaker;
import static org.springframework.cloud.gateway.server.mvc.filter.LoadBalancerFilterFunctions.lb;
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> gatewayRouterFunctionsCircuitBreakerFallbackToGatewayRoute() {
        return route("ingredients")
                .route(path("/ingredients/**"), http())
                .filter(lb("ingredients"))
                .filter(circuitBreaker("fetchIngredients", URI.create("forward:/fallback")))
                .build()
            .and(route("ingredients-fallback")
                .route(path("/fallback"), http())
                .before(uri("http://localhost:9994"))
                .before(fallbackHeaders())
                .build());
    }
}

在此示例中,当断路器运行时发生执行异常后,请求会被转发到运行在 localhost:9994 的应用中的 fallback 端点或处理器。FallbackHeaders 过滤器会将包含异常类型、消息以及(如果可用)根因异常类型和消息的头信息添加到该请求中。

您可以通过设置以下参数的值来覆盖配置中的头信息名称(显示为默认值)

  • executionExceptionTypeHeaderName"Execution-Exception-Type")(执行异常类型头名称)

  • executionExceptionMessageHeaderName"Execution-Exception-Message")(执行异常消息头名称)

  • rootCauseExceptionTypeHeaderName"Root-Cause-Exception-Type")(根因异常类型头名称)

  • rootCauseExceptionMessageHeaderName"Root-Cause-Exception-Message")(根因异常消息头名称)

有关断路器和网关的更多信息,请参阅Spring Cloud CircuitBreaker 过滤器部分