spring cloud gateway 自定义负载均衡

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spring cloud gateway 自定义负载均衡

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相关类及接口

LoadbalancerCliientFilter：使用ribbon负载均衡，默认使用该类，该标记为不推荐使用

/** @deprecated */
@Deprecated
public class LoadBalancerClientFilter implements GlobalFilter, Ordered {
    public static final int LOAD_BALANCER_CLIENT_FILTER_ORDER = 10100;
    private static final Log log = LogFactory.getLog(LoadBalancerClientFilter.class);
    protected final LoadBalancerClient loadBalancer;
    private LoadBalancerProperties properties;

    public LoadBalancerClientFilter(LoadBalancerClient loadBalancer, LoadBalancerProperties properties) {
        this.loadBalancer = loadBalancer;
        this.properties = properties;
    }

    public int getOrder() {
        return 10100;
    }

    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        URI url = (URI)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
        String schemePrefix = (String)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR);
        if (url != null && ("lb".equals(url.getScheme()) || "lb".equals(schemePrefix))) {
            ServerWebExchangeUtils.addOriginalRequestUrl(exchange, url);
            if (log.isTraceEnabled()) {
                log.trace("LoadBalancerClientFilter url before: " + url);
            }

            ServiceInstance instance = this.choose(exchange);
            if (instance == null) {
                throw NotFoundException.create(this.properties.isUse404(), "Unable to find instance for " + url.getHost());
            } else {
                URI uri = exchange.getRequest().getURI();
                String overrideScheme = instance.isSecure() ? "https" : "http";
                if (schemePrefix != null) {
                    overrideScheme = url.getScheme();
                }

                URI requestUrl = this.loadBalancer.reconstructURI(new DelegatingServiceInstance(instance, overrideScheme), uri);
                if (log.isTraceEnabled()) {
                    log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);
                }

                exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, requestUrl);
                return chain.filter(exchange);
            }
        } else {
            return chain.filter(exchange);
        }
    }

    protected ServiceInstance choose(ServerWebExchange exchange) {
        return this.loadBalancer.choose(((URI)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR)).getHost());
    }
}

说明：默认使用该类，可通过下述方法使用ReactiveLoadbalancerClientFilter

​"You already have RibbonLoadBalancerClient on your classpath. It will be used by default. 
As Spring Cloud Ribbon is in maintenance mode. We recommend switching to " + BlockingLoadBalancerClient.class.getSimpleName() + " instead. 
In order to use it, set the value of `spring.cloud.loadbalancer.ribbon.enabled` to `false` 
or remove spring-cloud-starter-netflix-ribbon from your project."

ReactiveLoadBalancerClientFilter：负载均衡拦截器

public class ReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {
    private static final Log log = LogFactory.getLog(ReactiveLoadBalancerClientFilter.class);
    private static final int LOAD_BALANCER_CLIENT_FILTER_ORDER = 10150;
    private final LoadBalancerClientFactory clientFactory;
    private LoadBalancerProperties properties;

    public ReactiveLoadBalancerClientFilter(LoadBalancerClientFactory clientFactory, LoadBalancerProperties properties) {
        this.clientFactory = clientFactory;
        this.properties = properties;
    }

    public int getOrder() {
        return 10150;
    }

    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        URI url = (URI)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
        String schemePrefix = (String)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR);
        if (url != null && ("lb".equals(url.getScheme()) || "lb".equals(schemePrefix))) {
                            //url不为null且协议为lb，或者url以lb开头

            ServerWebExchangeUtils.addOriginalRequestUrl(exchange, url);
            if (log.isTraceEnabled()) {
                log.trace(ReactiveLoadBalancerClientFilter.class.getSimpleName() + " url before: " + url);
            }

            return this.choose(exchange).doOnNext((response) -> {
                            //获取ServiceInstance实例，进行一些处理

                if (!response.hasServer()) {
                            //如果没有serviceInstance，直接抛出异常

                    throw NotFoundException.create(this.properties.isUse404(), "Unable to find instance for " + url.getHost());
                } else {    //如果有serviceInstance，进行相关处理
                    URI uri = exchange.getRequest().getURI();
                    String overrideScheme = null;
                    if (schemePrefix != null) {
                        overrideScheme = url.getScheme();
                    }

                    DelegatingServiceInstance serviceInstance = new DelegatingServiceInstance((ServiceInstance)response.getServer(), overrideScheme);
                    URI requestUrl = LoadBalancerUriTools.reconstructURI(serviceInstance, uri);
                    if (log.isTraceEnabled()) {
                        log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);
                    }

                    exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, requestUrl);
                }
            }).then(chain.filter(exchange));
        } else {
            return chain.filter(exchange); //如果获取不到serviceInstance，直接进行后续过滤
        }
    }

    private Mono<Response<ServiceInstance>> choose(ServerWebExchange exchange) {
        URI uri = (URI)exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
        ReactorLoadBalancer<ServiceInstance> loadBalancer = (ReactorLoadBalancer)this.clientFactory.getInstance(uri.getHost(), ReactorLoadBalancer.class, new Class[]{ServiceInstance.class});
        if (loadBalancer == null) {
            throw new NotFoundException("No loadbalancer available for " + uri.getHost());
        } else {
            return loadBalancer.choose(this.createRequest());
        }
    }//选择服务实例

    private Request createRequest() {
        return ReactiveLoadBalancer.REQUEST;
    }
}

ReactorLoadBalancer：负载均衡接口

public interface ReactorLoadBalancer<T> extends ReactiveLoadBalancer<T> {
    Mono<Response<T>> choose(Request request);

    default Mono<Response<T>> choose() {
        return this.choose(REQUEST);
    }
}

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public interface ReactorServiceInstanceLoadBalancer extends ReactorLoadBalancer<ServiceInstance> {
}

RoundRobinLoadbalancer：负载均衡使用轮询

public class RoundRobinLoadBalancer implements ReactorServiceInstanceLoadBalancer {
    private static final Log log = LogFactory.getLog(RoundRobinLoadBalancer.class);
    private final AtomicInteger position;

    private ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;
    private final String serviceId;

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构造方法

    public RoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId) {
    public RoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId, int seedPosition) {

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普通方法

    public Mono<Response<ServiceInstance>> choose(Request request) {
        if (this.serviceInstanceListSupplierProvider != null) {
            ServiceInstanceListSupplier supplier = (ServiceInstanceListSupplier)this.serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);
            return ((Flux)supplier.get()).next().map(this::getInstanceResponse);
        } else {
            ServiceInstanceSupplier supplier = (ServiceInstanceSupplier)this.serviceInstanceSupplier.getIfAvailable(NoopServiceInstanceSupplier::new);
            return ((Flux)supplier.get()).collectList().map(this::getInstanceResponse);
        }
    }

    private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {
        if (instances.isEmpty()) {
            log.warn("No servers available for service: " + this.serviceId);
            return new EmptyResponse();
        } else {
            int pos = Math.abs(this.position.incrementAndGet());
            ServiceInstance instance = (ServiceInstance)instances.get(pos % instances.size());
            return new DefaultResponse(instance);
        }
    }//使用轮询获取实例
}

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示例

参数id为偶数时，调用相关接口输出hello new version

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网关

配置文件

spring:
  application:
    name: hello-gateway
  cloud:
    consul:
      host: 172.18.0.20
      port: 8500
    loadbalancer:
      ribbon:
        enabled: false
    gateway:
      routes:
        - id: myRoute
          uri: lb://hello-service
          predicates:
            - Path=/hello

自定义过滤器

@Component
public class CustomLoadBalancerClientFilter implements GlobalFilter, Ordered {
    private static final Log log = LogFactory.getLog(org.springframework.cloud.gateway.filter.ReactiveLoadBalancerClientFilter.class);

    @Resource
    private final LoadBalancerClientFactory clientFactory;

    @Resource
    private LoadBalancerProperties properties;

    public CustomLoadBalancerClientFilter(LoadBalancerClientFactory clientFactory, LoadBalancerProperties properties) {
        this.clientFactory = clientFactory;
        this.properties = properties;
    }

    public int getOrder() {
        return 10149;
    }

    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        URI url = exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
        String schemePrefix = exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_SCHEME_PREFIX_ATTR);
        if (url != null && ("lb".equals(url.getScheme()) || "lb".equals(schemePrefix))) {
            ServerWebExchangeUtils.addOriginalRequestUrl(exchange, url);
            if (log.isTraceEnabled()) {
                log.trace(ReactiveLoadBalancerClientFilter.class.getSimpleName() + " url before: " + url);
            }

            return this.choose(exchange).doOnNext((response) -> {
                if (!response.hasServer()) {
                    throw NotFoundException.create(this.properties.isUse404(), "Unable to find instance for " + url.getHost());
                } else {
                    URI uri = exchange.getRequest().getURI();
                    String overrideScheme = null;
                    if (schemePrefix != null) {
                        overrideScheme = url.getScheme();
                    }

                    int id=Integer.parseInt(Objects.requireNonNull(exchange.getRequest().getQueryParams().getFirst("id")));
                    if (id%2==0){
                        while (!"new".equals(response.getServer().getMetadata().get("version"))){
                            try {
                                response=this.choose(exchange).toFuture().get();
                            }catch (Exception e){
                                System.out.println(e.getMessage());
                            }
                        }
                    }

                    DelegatingServiceInstance serviceInstance = new DelegatingServiceInstance(response.getServer(), overrideScheme);

                    System.out.println(exchange.getRequest().getQueryParams().getFirst("id")+"对应server的version为："+serviceInstance.getMetadata().get("version"));
                    URI requestUrl = LoadBalancerUriTools.reconstructURI(serviceInstance, uri);
                    if (log.isTraceEnabled()) {
                        log.trace("LoadBalancerClientFilter url chosen: " + requestUrl);
                    }

                    exchange.getAttributes().put(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR, requestUrl);
                }
            }).then(chain.filter(exchange));
        } else {
            return chain.filter(exchange);
        }
    }

    private Mono<Response<ServiceInstance>> choose(ServerWebExchange exchange) {
        URI uri = exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
        assert uri != null;
        ReactorLoadBalancer<ServiceInstance> loadBalancer = this.clientFactory.getInstance(uri.getHost(), ReactorLoadBalancer.class, new Class[]{ServiceInstance.class});
        if (loadBalancer == null) {
            throw new NotFoundException("No loadbalancer available for " + uri.getHost());
        } else {
            return loadBalancer.choose(this.createRequest());
        }
    }

    private Request createRequest() {
        return ReactiveLoadBalancer.REQUEST;
    }
}

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同名应用hello-service1

配置文件

spring:
  application:
    name: hello-service
  cloud:
    consul:
      host: 172.18.0.20
      port: 8500
      discovery:
        instance-id: ${spring.application.name}-${random.int}
        tags: version=old

controller 层

@RestController
public class HelloController {

    @RequestMapping("/hello")
    public String hello(){
        return "hello old version";
    }
}

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同名应用hello-service2

配置文件

spring:
  application:
    name: hello-service
  cloud:
    consul:
      host: 172.18.0.20
      port: 8500
      discovery:
        instance-id: ${spring.application.name}-${random.int}
        tags: version=new

controller 层

@RestController
public class HelloController {

    @RequestMapping("/hello")
    public String hello(){
        return "hello new version";
    }
}

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测试输出

consul注册的应用

        

参数测试

       

当id为偶数时，输出为hello new version