spring cloud gateway集成hystrix的方法

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spring cloud gateway集成hystrix

本文主要研究一下spring cloud gateway如何集成hystrix

maven

<dependency>            <groupId>org.springframework.cloud</groupId>            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>        </dependency>

添加spring-cloud-starter-netflix-hystrix依赖，开启hystrix

配置实例

hystrix.command.fallbackcmd.execution.isolation.thread.timeoutInMilliseconds: 5000spring:  cloud:    gateway:      discovery:        locator:          enabled: true      routes:      - id: employee-service        uri: lb://employee-service        predicates:        - Path=/employeepublic class HystrixGatewayFilterFactory extends AbstractGatewayFilterFactory<HystrixGatewayFilterFactory.Config> {    public static final String FALLBACK_URI = "fallbackUri";    private final DispatcherHandler dispatcherHandler;    public HystrixGatewayFilterFactory(DispatcherHandler dispatcherHandler) {        super(Config.class);        this.dispatcherHandler = dispatcherHandler;    }    @Override    public List<String> shortcutFieldOrder() {        return Arrays.asList(NAME_KEY);    }    public GatewayFilter apply(String routeId, Consumer<Config> consumer) {        Config config = newConfig();        consumer.accept(config);        if (StringUtils.isEmpty(config.getName()) && !StringUtils.isEmpty(routeId)) {            config.setName(routeId);        }        return apply(config);    }    @Override    public GatewayFilter apply(Config config) {        //TODO: if no name is supplied, generate one from command id (useful for default filter)        if (config.setter == null) {            Assert.notNull(config.name, "A name must be supplied for the Hystrix Command Key");            HystrixCommandGroupKey groupKey = HystrixCommandGroupKey.Factory.asKey(getClass().getSimpleName());            HystrixCommandKey commandKey = HystrixCommandKey.Factory.asKey(config.name);            config.setter = Setter.withGroupKey(groupKey)                    .andCommandKey(commandKey);        }        return (exchange, chain) -> {            RouteHystrixCommand command = new RouteHystrixCommand(config.setter, config.fallbackUri, exchange, chain);            return Mono.create(s -> {                Subscription sub = command.toObservable().subscribe(s::success, s::error, s::success);                s.onCancel(sub::unsubscribe);            }).onErrorResume((Function<Throwable, Mono<Void>>) throwable -> {                if (throwable instanceof HystrixRuntimeException) {                    HystrixRuntimeException e = (HystrixRuntimeException) throwable;                    if (e.getFailureType() == TIMEOUT) { //TODO: optionally set status                        setResponseStatus(exchange, HttpStatus.GATEWAY_TIMEOUT);                        return exchange.getResponse().setComplete();                    }                }                return Mono.error(throwable);            }).then();        };    }    //......}

这里创建了RouteHystrixCommand，将其转换为Mono，然后在onErrorResume的时候判断如果HystrixRuntimeException的failureType是FailureType.TIMEOUT类型的话，则返回GATEWAY_TIMEOUT(504, "Gateway Timeout")状态码。

RouteHystrixCommand

//TODO: replace with HystrixMonoCommand that we write    private class RouteHystrixCommand extends HystrixObservableCommand<Void> {        private final URI fallbackUri;        private final ServerWebExchange exchange;        private final GatewayFilterChain chain;        RouteHystrixCommand(Setter setter, URI fallbackUri, ServerWebExchange exchange, GatewayFilterChain chain) {            super(setter);            this.fallbackUri = fallbackUri;            this.exchange = exchange;            this.chain = chain;        }        @Override        protected Observable<Void> construct() {            return RxReactiveStreams.toObservable(this.chain.filter(exchange));        }        @Override        protected Observable<Void> resumeWithFallback() {            if (this.fallbackUri == null) {                return super.resumeWithFallback();            }            //TODO: copied from RouteToRequestUrlFilter            URI uri = exchange.getRequest().getURI();            //TODO: assume always?            boolean encoded = containsEncodedParts(uri);            URI requestUrl = UriComponentsBuilder.fromUri(uri)                    .host(null)                    .port(null)                    .uri(this.fallbackUri)                    .build(encoded)                    .toUri();            exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, requestUrl);            ServerHttpRequest request = this.exchange.getRequest().mutate().uri(requestUrl).build();            ServerWebExchange mutated = exchange.mutate().request(request).build();            return RxReactiveStreams.toObservable(HystrixGatewayFilterFactory.this.dispatcherHandler.handle(mutated));        }    }

• 这里重写了construct方法，RxReactiveStreams.toObservable(this.chain.filter(exchange))，将reactor的Mono转换为rxjava的Observable

• 这里重写了resumeWithFallback方法，针对有fallbackUri的情况，重新路由到fallbackUri的地址

Config

public static class Config {        private String name;        private Setter setter;        private URI fallbackUri;        public String getName() {            return name;        }        public Config setName(String name) {            this.name = name;            return this;        }        public Config setFallbackUri(String fallbackUri) {            if (fallbackUri != null) {                setFallbackUri(URI.create(fallbackUri));            }            return this;        }        public URI getFallbackUri() {            return fallbackUri;        }        public void setFallbackUri(URI fallbackUri) {            if (fallbackUri != null && !"forward".equals(fallbackUri.getScheme())) {                throw new IllegalArgumentException("Hystrix Filter currently only supports 'forward' URIs, found " + fallbackUri);            }            this.fallbackUri = fallbackUri;        }        public Config setSetter(Setter setter) {            this.setter = setter;            return this;        }    }

可以看到Config校验了fallbackUri，如果不为null，则必须以forward开头

小结

spring cloud gateway集成hystrix，分为如下几步：

• 添加spring-cloud-starter-netflix-hystrix依赖

• 在对应route的filter添加name为Hystrix的filter，同时指定hystrix command的名称，及其fallbackUri(可选)

• 指定该hystrix command的超时时间等。

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