Spring Cloud中Zuul服务器的回退方法 [英] Fallback methods at Zuul server in Spring cloud
问题描述
我是Spring Cloud Netflix的新手，对此有一些疑问.
我将API网关与在Zuul边缘服务器上运行的Hystrix一起使用，我想确保我是否正确理解以下行为:
I am new in Spring Cloud Netflix and have some questions concerning it.
I am using the API Gateway together with Hystrix running at Zuul edge server and I would like to make sure if I understand the following behavior correctly:
我杀死了一个在"API网关"后面运行的微服务，然后强制hystrix打开电路.在那之后(大约10秒钟)，我向未运行的微服务发送了一个请求，并收到TIMEOUT错误.但是，当我在很短的时间内(最多1秒)发送许多(数十个)请求时，我会收到SHORTCIRCUIUI OPEN错误.
我很惊讶为什么在电路断开的情况下仍然收到超时错误，因此应使用hystrix来避免此类故障.但是我猜想原因是，如果自上次请求以来的时间> circuitBreaker.sleepWindowInMilliseconds，则API网关会尝试再次连接到微服务以检查其是否仍然存在，但不是，因此->超时.这也可以解释为什么我在短时间内对许多请求都出现SHORTCIRCUIUI OPEN错误.
I kill a microservice running "behind" API Gateway then I force hystrix to open the circuit. After that (ca 10 seconds) I send a request to the non-running microservice and receive TIMEOUT error. However when I send many (tens) of requests in a very short time (up to 1 sec), I receive SHORTCIRCUIT OPEN error.
I was surprised why I receive TIMEOUT error although the circuit is open and therefore hystrix should come to play to avoid such kind of failures. But I guess the reason is that if time since last request > circuitBreaker.sleepWindowInMilliseconds, then the API Gateway tries to connect to the microservice again to check if it's alive, but it wasn't, thus -> TIMEOUT. That would also explain, why I got SHORTCIRCUIT OPEN error on many requests in short time.
接下来的事情是，当我收到"TIMEOUT"或"SHORTCIRCUIT"错误时，我得到了:
The next thing is that as I receive "TIMEOUT" or "SHORTCIRCUIT" error I got:
HystrixRuntimeException: Microservice (timed-out | short-circuited) and no fallback available
如何在zuul服务器上指定一个后备(所有路由都可以相同)以避免这种异常?
到现在为止我一直在尝试:
How can I specify a fallback at zuul server (this can be the same for all routes) to avoid this exception ?
What I have tried until now:
-
根据此设置执行隔离穿线策略 为了避免超时:
According this to I set execution isolation strategy to THREAD to avoid time-out:
hystrix: command.default.execution.isolation.strategy:螺纹
hystrix: command.default.execution.isolation.strategy: THREAD
但是在查看hystrix.stream之后，我得到了propertyValue_executionIsolationStrategy":"SEMAPHORE"
but after looking at the hystrix.stream I got propertyValue_executionIsolationStrategy":"SEMAPHORE"
- 在 github 上似乎有解决方案的暗示通过编写自定义的RibbonCommand并覆盖getFallback()，但在查看
- There seems to be a hint for solution on github by writing a custom RibbonCommand and overriding getFallback(), but after looking at RibbonCommand interface. I found out, that neither RibbonCommand nor its super interfaces doesn't define such a method.
我的API网关服务:
@SpringBootApplication
@EnableSidecar // This annotation includes @EnableCircuitBreaker, @EnableDiscoveryClient, and @EnableZuulProxy
@EnableHystrixDashboard
public class ApiGatewayApplication {
public static void main(String[] args) {
SpringApplication.run(ApiGatewayApplication.class, args);
}
}
application.yml
application.yml
server:
port: 10000
sidecar:
port: 8000
endpoints:
restart:
enabled: true
shutdown:
enabled: true
health:
sensitive: false
eureka:
client:
registerWithEureka: true
fetchRegistry: true
serviceUrl:
defaultZone: http://localhost:8761/eureka/
zuul:
routes:
microservice:
path: /microservice/**
hystrix:
command.default.execution.isolation.strategy: THREAD
debug: true
推荐答案
最新版本在Zuul级别支持回退.这是通过扩展ZuulFallbackProvider来完成的.请访问以下链接获取示例: https://github.com/spring-cloud-samples/zuul-server/blob/master/src/main/java/zuulserver/ZuulServerApplication.java
The latest release supports fallback at Zuul level. It is done by extending the ZuulFallbackProvider. Please visit the below link for an example: https://github.com/spring-cloud-samples/zuul-server/blob/master/src/main/java/zuulserver/ZuulServerApplication.java
对于某些类型的路由配置(例如，如果您具有基于url的配置)，回退触发本身不会完成
The fallback triggering itself is not done for certain types of route configurations (for eg if you have a url based config)
这些简单的url路由不会作为HystrixCommand执行，也无法通过Ribbon来平衡多个URL."
"These simple url-routes don’t get executed as a HystrixCommand nor can you loadbalance multiple URLs with Ribbon."
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