gateway 负载均衡

自定义gateway负载均衡策略

• 优先选择与网关运行在同一台机器上的服务实例（即主机地址为本地IP的实例）。如果找不到，则随机选择一个实例

@Slf4j
@AllArgsConstructor
public class CustomSpringCloudLoadBalancer implements ReactorServiceInstanceLoadBalancer {

    /**
     * 目标服务名
     */
    private final String serviceId;

    /**
     * 服务实例列表
     */
    private final ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;

    @Override
    public Mono<Response<ServiceInstance>> choose(Request request) {
        ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider.getIfAvailable(NoopServiceInstanceListSupplier::new);
        return supplier.get(request).next().map(serviceInstances -> processInstanceResponse(supplier, serviceInstances));
    }

    private Response<ServiceInstance> processInstanceResponse(ServiceInstanceListSupplier supplier,
                                                              List<ServiceInstance> serviceInstances) {
        Response<ServiceInstance> serviceInstanceResponse = getInstanceResponse(serviceInstances);
        if (supplier instanceof SelectedInstanceCallback && serviceInstanceResponse.hasServer()) {
            ((SelectedInstanceCallback) supplier).selectedServiceInstance(serviceInstanceResponse.getServer());
        }
        return serviceInstanceResponse;
    }

    private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances) {
        if (instances.isEmpty()) {
            if (log.isWarnEnabled()) {
                log.warn("No servers available for service: " + serviceId);
            }
            return new EmptyResponse();
        }
        for (ServiceInstance instance : instances) {
            if (NetUtil.localIpv4s().contains(instance.getHost())) {
                //                log.info("Choose instance: {}", instance.getHost());
                return new DefaultResponse(instance);
            }
        }
        return new DefaultResponse(instances.get(ThreadLocalRandom.current().nextInt(instances.size())));
    }

}

@SuppressWarnings("all")
@Configuration(proxyBeanMethods = false)
public class CustomLoadBalanceClientConfiguration {

    @Bean
    @ConditionalOnBean(LoadBalancerClientFactory.class)
    public ReactorLoadBalancer<ServiceInstance> customLoadBalancer(Environment environment,
                                                                   LoadBalancerClientFactory loadBalancerClientFactory) {
        String name = environment.getProperty(LoadBalancerClientFactory.PROPERTY_NAME);
        return new CustomSpringCloudLoadBalancer(name,
                loadBalancerClientFactory.getLazyProvider(name, ServiceInstanceListSupplier.class));
    }
}

@LoadBalancerClients(defaultConfiguration = CustomLoadBalanceClientConfiguration.class)
public class CustomLoadBalanceAutoConfiguration {

}