@ -565,112 +565,6 @@ This removes duplicate values of `Access-Control-Allow-Credentials` and `Access-
@@ -565,112 +565,6 @@ This removes duplicate values of `Access-Control-Allow-Credentials` and `Access-
The `DedupeResponseHeader` filter also accepts an optional `strategy` parameter.
The accepted values are `RETAIN_FIRST` (default), `RETAIN_LAST`, and `RETAIN_UNIQUE`.
[[hystrix]]
=== The Hystrix `GatewayFilter` Factory
NOTE: https://cloud.spring.io/spring-cloud-netflix/multi/multi__modules_in_maintenance_mode.html[Netflix has put Hystrix in maintenance mode]. We suggest you use the <<spring-cloud-circuitbreaker-filter-factory, Spring Cloud CircuitBreaker
Gateway Filter>> with Resilience4J, as support for Hystrix will be removed in a future release.
https://github.com/Netflix/Hystrix[Hystrix] is a library from Netflix that implements the https://martinfowler.com/bliki/CircuitBreaker.html[circuit breaker pattern].
The Hystrix `GatewayFilter` lets you introduce circuit breakers to your gateway routes, protecting your services from cascading failures and letting you provide fallback responses in the event of downstream failures.
To enable Hystrix `GatewayFilter` instances in your project, add a dependency on `spring-cloud-starter-netflix-hystrix` from https://cloud.spring.io/spring-cloud-netflix/[Spring Cloud Netflix].
The Hystrix `GatewayFilter` factory requires a single `name` parameter, which is the name of the `HystrixCommand`.
The following example configures a Hystrix `GatewayFilter`:
.application.yml
====
[source,yaml]
----
spring:
cloud:
gateway:
routes:
- id: hystrix_route
uri: https://example.org
filters:
- Hystrix=myCommandName
----
====
This wraps the remaining filters in a `HystrixCommand` with a command name of `myCommandName`.
The Hystrix filter can also accept an optional `fallbackUri` parameter. Currently, only `forward:` schemed URIs are supported. If the fallback is called, the request is forwarded to the controller matched by the URI.
This will forward to the `/incaseoffailureusethis` URI when the Hystrix fallback is called. Note that this example also demonstrates (optional) Spring Cloud Netflix Ribbon load-balancing (defined the `lb` prefix on the destination URI).
The primary scenario is to use the `fallbackUri` to an internal controller or handler within the gateway app.
However, you can also reroute the request to a controller or handler in an external application, as follows:
.application.yml
====
[source,yaml]
----
spring:
cloud:
gateway:
routes:
- id: ingredients
uri: lb://ingredients
predicates:
- Path=//ingredients/**
filters:
- name: Hystrix
args:
name: fetchIngredients
fallbackUri: forward:/fallback
- id: ingredients-fallback
uri: http://localhost:9994
predicates:
- Path=/fallback
----
====
In this example, there is no `fallback` endpoint or handler in the gateway application.
However, there is one in another application, registered under `http://localhost:9994`.
In case of the request being forwarded to the fallback, the Hystrix Gateway filter also provides the `Throwable` that has caused it.
It is added to the `ServerWebExchange` as the `ServerWebExchangeUtils.HYSTRIX_EXECUTION_EXCEPTION_ATTR` attribute, which you can use when handling the fallback within the gateway application.
For the external controller/handler scenario, you can add headers with exception details.
You can find more information on doing so in the <<fallback-headers, FallbackHeaders GatewayFilter Factory section>>.
You can configured Hystrix settings (such as timeouts) with global defaults or on a route-by-route basis by using application properties, as explained on the https://github.com/Netflix/Hystrix/wiki/Configuration[Hystrix wiki].
To set a five-second timeout for the example route shown earlier, you could use the following configuration:
Spencer Gibb
5 years ago