https://github.com/zq2599/blog_demos
内容:所有原创文章分类汇总及配套源码,涉及Java、Docker、Kubernetes、DevOPS等;
简单来说Spring Cloud Gateway的断路器功能是通过内置filter实现的,这个filter使用了Spring Cloud断路器;
官方说多个断路器的库都可以用在Spring Cloud Gateway,但是并没有说具体是哪些,这就郁闷了,此时咱们去了解一位牛人的观点:Piotr Mińkowski,就是下面这本书的作者:
名称 | 链接 | 备注 |
---|---|---|
项目主页 | https://github.com/zq2599/blog_demos | 该项目在GitHub上的主页 |
git仓库地址(https) | https://github.com/zq2599/blog_demos.git | 该项目源码的仓库地址,https协议 |
git仓库地址(ssh) | git@github.com:zq2599/blog_demos.git | 该项目源码的仓库地址,ssh协议 |
咱们要准备一个可控的web接口,通过参数控制它成功或者失败,这样才能触发断路器
本篇的实战中,服务提供者依旧是<font color="blue">provider-hello</font>,为了满足本次实战的需求,咱们在Hello.java文件中增加一个web接口,对应的源码如下:
@RequestMapping(value = "/account/{id}", method = RequestMethod.GET)
public String account(@PathVariable("id") int id) throws InterruptedException {
if(1==id) {
Thread.sleep(500);
}
return Constants.ACCOUNT_PREFIX + dateStr();
}
上述代码很简单:就是接收id参数,如果等于1就延时五百毫秒,不等于1就立即返回
如果把断路器设置为超过两百毫秒就算失败,那么通过控制id参数的值,咱们就能模拟请求成功或者失败了,<font color="blue">这是验证断路器功能的关键</font>
准备完成,开始写代码
在父工程<font color="blue">spring-cloud-tutorials</font>下面新增子工程<font color="blue">circuitbreaker-gateway</font>
增加以下依赖
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-circuitbreaker-reactor-resilience4j</artifactId>
</dependency>
server:
#服务端口
port: 8081
spring:
application:
name: circuitbreaker-gateway
cloud:
gateway:
routes:
- id: path_route
uri: http://127.0.0.1:8082
predicates:
- Path=/hello/**
filters:
- name: CircuitBreaker
args:
name: myCircuitBreaker
package com.bolingcavalry.circuitbreakergateway;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class CircuitbreakerApplication {
public static void main(String[] args) {
SpringApplication.run(CircuitbreakerApplication.class,args);
}
}
package com.bolingcavalry.circuitbreakergateway.config;
import io.github.resilience4j.circuitbreaker.CircuitBreakerConfig;
import io.github.resilience4j.timelimiter.TimeLimiterConfig;
import org.springframework.cloud.circuitbreaker.resilience4j.ReactiveResilience4JCircuitBreakerFactory;
import org.springframework.cloud.circuitbreaker.resilience4j.Resilience4JConfigBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.time.Duration;
@Configuration
public class CustomizeCircuitBreakerConfig {
@Bean
public ReactiveResilience4JCircuitBreakerFactory defaultCustomizer() {
CircuitBreakerConfig circuitBreakerConfig = CircuitBreakerConfig.custom() //
.slidingWindowType(CircuitBreakerConfig.SlidingWindowType.TIME_BASED) // 滑动窗口的类型为时间窗口
.slidingWindowSize(10) // 时间窗口的大小为60秒
.minimumNumberOfCalls(5) // 在单位时间窗口内最少需要5次调用才能开始进行统计计算
.failureRateThreshold(50) // 在单位时间窗口内调用失败率达到50%后会启动断路器
.enableAutomaticTransitionFromOpenToHalfOpen() // 允许断路器自动由打开状态转换为半开状态
.permittedNumberOfCallsInHalfOpenState(5) // 在半开状态下允许进行正常调用的次数
.waitDurationInOpenState(Duration.ofSeconds(5)) // 断路器打开状态转换为半开状态需要等待60秒
.recordExceptions(Throwable.class) // 所有异常都当作失败来处理
.build();
ReactiveResilience4JCircuitBreakerFactory factory = new ReactiveResilience4JCircuitBreakerFactory();
factory.configureDefault(id -> new Resilience4JConfigBuilder(id)
.timeLimiterConfig(TimeLimiterConfig.custom().timeoutDuration(Duration.ofMillis(200)).build())
.circuitBreakerConfig(circuitBreakerConfig).build());
return factory;
}
}
上述代码有一次需要注意:<font color="blue">timeLimiterConfig</font>方法设置了超时时间,服务提供者如果超过200毫秒没有响应,Spring Cloud Gateway就会向调用者返回失败
开发完成了,接下来要考虑的是如何验证
package com.bolingcavalry.circuitbreakergateway;
import io.github.resilience4j.circuitbreaker.CircuitBreaker;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit.jupiter.SpringExtension;
import org.springframework.test.web.reactive.server.WebTestClient;
@SpringBootTest
@ExtendWith(SpringExtension.class)
@AutoConfigureWebTestClient
public class CircuitbreakerTest {
// 测试的总次数
private static int i=0;
@Autowired
private WebTestClient webClient;
@Test
@RepeatedTest(100)
void testHelloPredicates() throws InterruptedException {
// 低于50次时,gen在0和1之间切换,也就是一次正常一次超时,
// 超过50次时,gen固定为0,此时每个请求都不会超时
int gen = (i<50) ? (i % 2) : 0;
// 次数加一
i++;
final String tag = "[" + i + "]";
// 发起web请求
webClient.get()
.uri("/hello/account/" + gen)
.accept(MediaType.APPLICATION_JSON)
.exchange()
.expectBody(String.class).consumeWith(result -> System.out.println(tag + result.getRawStatusCode() + " - " + result.getResponseBody()));
Thread.sleep(1000);
}
}
启动nacos(服务提供者依赖的)
启动子工程<font color="blue">provider-hello</font>
运行咱们刚才开发的单元测试类,控制台输入的内容截取部分如下,稍后会有分析:
[2]504 - {"timestamp":"2021-08-28T02:55:42.920+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"594efed1"}
[3]200 - Account2021-08-28 10:55:43
[4]504 - {"timestamp":"2021-08-28T02:55:45.177+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"427720b"}
[5]200 - Account2021-08-28 10:55:46
[6]503 - {"timestamp":"2021-08-28T02:55:47.227+00:00","path":"/hello/account/1","status":503,"error":"Service Unavailable","message":"","requestId":"6595d7f4"}
[7]503 - {"timestamp":"2021-08-28T02:55:48.250+00:00","path":"/hello/account/0","status":503,"error":"Service Unavailable","message":"","requestId":"169ae1c"}
[8]503 - {"timestamp":"2021-08-28T02:55:49.259+00:00","path":"/hello/account/1","status":503,"error":"Service Unavailable","message":"","requestId":"53b695a1"}
[9]503 - {"timestamp":"2021-08-28T02:55:50.269+00:00","path":"/hello/account/0","status":503,"error":"Service Unavailable","message":"","requestId":"4a072f52"}
[10]504 - {"timestamp":"2021-08-28T02:55:51.499+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"4bdd96c4"}
[11]200 - Account2021-08-28 10:55:52
[12]504 - {"timestamp":"2021-08-28T02:55:53.745+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"4e0e7eab"}
[13]200 - Account2021-08-28 10:55:54
[14]504 - {"timestamp":"2021-08-28T02:55:56.013+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"27685405"}
[15]503 - {"timestamp":"2021-08-28T02:55:57.035+00:00","path":"/hello/account/0","status":503,"error":"Service Unavailable","message":"","requestId":"3e40c5db"}
[16]503 - {"timestamp":"2021-08-28T02:55:58.053+00:00","path":"/hello/account/1","status":503,"error":"Service Unavailable","message":"","requestId":"2bf2698b"}
[17]503 - {"timestamp":"2021-08-28T02:55:59.075+00:00","path":"/hello/account/0","status":503,"error":"Service Unavailable","message":"","requestId":"38cb1840"}
[18]503 - {"timestamp":"2021-08-28T02:56:00.091+00:00","path":"/hello/account/1","status":503,"error":"Service Unavailable","message":"","requestId":"21586fa"}
[19]200 - Account2021-08-28 10:56:01
[20]504 - {"timestamp":"2021-08-28T02:56:02.325+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"4014d6d4"}
[21]200 - Account2021-08-28 10:56:03
[22]504 - {"timestamp":"2021-08-28T02:56:04.557+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"173a3b9d"}
[23]200 - Account2021-08-28 10:56:05
[24]504 - {"timestamp":"2021-08-28T02:56:06.811+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"aa8761f"}
[25]200 - Account2021-08-28 10:56:07
[26]504 - {"timestamp":"2021-08-28T02:56:09.057+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"769bfefc"}
[27]200 - Account2021-08-28 10:56:10
[28]504 - {"timestamp":"2021-08-28T02:56:11.314+00:00","path":"/hello/account/1","status":504,"error":"Gateway Timeout","message":"","requestId":"2fbcb6c0"}
[29]503 - {"timestamp":"2021-08-28T02:56:12.332+00:00","path":"/hello/account/0","status":503,"error":"Service Unavailable","message":"","requestId":"58e4e70f"}
[30]503 - {"timestamp":"2021-08-28T02:56:13.342+00:00","path":"/hello/account/1","status":503,"error":"Service Unavailable","message":"","requestId":"367651c5"}
通过上述测试可见,Spring Cloud Gateway通过返回码来告知调用者错误信息,这种方式不够友好,我们可以自定义fallback,在返回错误时由它来构建返回信息
再开发一个web接口,没错,就是在<font color="blue">circuitbreaker-gateway</font>工程中添加一个web接口:
package com.bolingcavalry.circuitbreakergateway.controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.text.SimpleDateFormat;
import java.util.Date;
@RestController
public class Fallback {
private String dateStr(){
return new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date());
}
/**
* 返回字符串类型
* @return
*/
@GetMapping("/myfallback")
public String helloStr() {
return "myfallback, " + dateStr();
}
}
server:
#服务端口
port: 8081
spring:
application:
name: circuitbreaker-gateway
cloud:
gateway:
routes:
- id: path_route
uri: http://127.0.0.1:8082
predicates:
- Path=/hello/**
filters:
- name: CircuitBreaker
args:
name: myCircuitBreaker
fallbackUri: forward:/myfallback
[2]200 - myfallback, 2021-08-28 11:15:02
[3]200 - Account2021-08-28 11:15:03
[4]200 - myfallback, 2021-08-28 11:15:04
[5]200 - Account2021-08-28 11:15:05
[6]200 - myfallback, 2021-08-28 11:15:06
[7]200 - myfallback, 2021-08-28 11:15:08
[8]200 - myfallback, 2021-08-28 11:15:09
[9]200 - myfallback, 2021-08-28 11:15:10
[10]200 - myfallback, 2021-08-28 11:15:11
[11]200 - Account2021-08-28 11:15:12
[12]200 - myfallback, 2021-08-28 11:15:13
[13]200 - Account2021-08-28 11:15:14
[14]200 - myfallback, 2021-08-28 11:15:15
gatewayFilterFactories.forEach(factory -> this.gatewayFilterFactories.put(factory.name(), factory));
然后会在loadGatewayFilters方法中使用这个map,找到上面put的bean;
最终的效果:路由配置中指定了name等于<font color="blue">CircuitBreaker</font>,即可对应SpringCloudCircuitBreakerFilterFactory类型的bean,因为它的name方法返回了"CircuitBreaker",如下图:
从上图来看,CircuitBreaker类型的filter应该是SpringCloudCircuitBreakerResilience4JFilterFactory,不过那只是从继承关系推断出来的,还差一个关键证据:在spring中,到底存不存在SpringCloudCircuitBreakerResilience4JFilterFactory类型的bean?
最终发现了GatewayResilience4JCircuitBreakerAutoConfiguration中的配置,可以证明SpringCloudCircuitBreakerResilience4JFilterFactory会被实例化并注册到spring:
@Bean
@ConditionalOnBean(ReactiveResilience4JCircuitBreakerFactory.class)
@ConditionalOnEnabledFilter
public SpringCloudCircuitBreakerResilience4JFilterFactory springCloudCircuitBreakerResilience4JFilterFactory(
ReactiveResilience4JCircuitBreakerFactory reactiveCircuitBreakerFactory,
ObjectProvider<DispatcherHandler> dispatcherHandler) {
return new SpringCloudCircuitBreakerResilience4JFilterFactory(reactiveCircuitBreakerFactory, dispatcherHandler);
}
综上所述,当您配置了CircuitBreaker过滤器时,实际上是SpringCloudCircuitBreakerResilience4JFilterFactory类在为您服务,而关键代码都集中在其父类SpringCloudCircuitBreakerFilterFactory中;
所以,要想深入了解Spring Cloud Gateway的断路器功能,请阅读SpringCloudCircuitBreakerFilterFactory.apply方法
相信您在看这段纯文字时,对欣宸的分析还是存在疑惑的,根据返回码就把断路器的状态确定了?例如504的时候到底是关闭还是半开呢?都有可能吧,所以,这种推测只能证明断路器正在工作,但是无法确定某个时刻具体的状态
所以,咱们需要一种更准确的方式知道每个时刻断路器的状态,这样才算对断路器有了深刻了解
接下来的文章中,咱们在今天的成果上更进一步,在请求中把断路器状态打印出来,那就...敬请期待吧,欣宸原创,从未让您失望;
微信搜索「程序员欣宸」,我是欣宸,期待与您一同畅游Java世界... https://github.com/zq2599/blog_demos
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