spring:
  application:
    name: canary-user-service
  cloud:
    nacos:
      discovery:
        username: nacos
        password: nacos
        server-addr: localhost:8848
        namespace: public
        register-enabled: true 
        metadata: { "grap-tag":"true" } # 標(biāo)識自己為灰度服務(wù)

private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances,
                                                          Request request) {
        // 實(shí)例為空
        if (instances.isEmpty()) {
            if (log.isWarnEnabled()) {
                log.warn("No servers available for service: " + this.serviceId);
            }
            return new EmptyResponse();
        } else { // 服務(wù)不為空
            RequestDataContext dataContext = (RequestDataContext) request.getContext();
            HttpHeaders headers = dataContext.getClientRequest().getHeaders();
            // 判斷是否為灰度發(fā)布（請求）
            if (headers.get(GlobalVariables.GRAY_KEY) != null &&
                    headers.get(GlobalVariables.GRAY_KEY).get(0).equals("true")) {
                // 灰度發(fā)布請求，得到新服務(wù)實(shí)例列表
                List<ServiceInstance> findInstances = instances.stream().
                        filter(s -> s.getMetadata().get(GlobalVariables.GRAY_KEY) != null &&
                                s.getMetadata().get(GlobalVariables.GRAY_KEY).equals("true"))
                        .toList();
                if (findInstances.size() > 0) { // 存在灰度發(fā)布節(jié)點(diǎn)
                    instances = findInstances;
                }
            } else { // 查詢非灰度發(fā)布節(jié)點(diǎn)
                // 灰度發(fā)布測試請求，得到新服務(wù)實(shí)例列表
                instances = instances.stream().
                        filter(s -> s.getMetadata().get(GlobalVariables.GRAY_KEY) == null ||
                                !s.getMetadata().get(GlobalVariables.GRAY_KEY).equals("true"))
                        .toList();
            }
            // 隨機(jī)正數(shù)值 ++i（ & 去負(fù)數(shù)）
            int pos = this.position.incrementAndGet() & Integer.MAX_VALUE;
            // ++i 數(shù)值 % 實(shí)例數(shù) 取模 -> 輪詢算法
            int index = pos % instances.size();
            // 得到服務(wù)實(shí)例方法
            ServiceInstance instance = (ServiceInstance) instances.get(index);
            return new DefaultResponse(instance);
        }
    }

package com.example.gateway.config;

import com.loadbalancer.canary.common.GlobalVariables;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Component
public class LoadBalancerFilter implements GlobalFilter {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        // 得到 request、response 對象
        ServerHttpRequest request = exchange.getRequest();
        ServerHttpResponse response = exchange.getResponse();
        if (request.getQueryParams().getFirst(GlobalVariables.GRAY_KEY) != null) {
            // 設(shè)置金絲雀標(biāo)識
            response.getHeaders().set(GlobalVariables.GRAY_KEY,
                    "true");
        }
        // 此步驟正常，執(zhí)行下一步
        return chain.filter(exchange);
    }
}

import feign.RequestInterceptor;
import feign.RequestTemplate;
import jakarta.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import java.util.Enumeration;
import java.util.LinkedHashMap;
import java.util.Map;

@Component
public class FeignRequestInterceptor implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate template) {
        // 從 RequestContextHolder 中獲取 HttpServletRequest
        ServletRequestAttributes attributes = (ServletRequestAttributes)
                RequestContextHolder.getRequestAttributes();
        // 獲取 RequestContextHolder 中的信息
        Map<String, String> headers = getHeaders(attributes.getRequest());
        // 放入 openfeign 的 RequestTemplate 中
        for (Map.Entry<String, String> entry : headers.entrySet()) {
            template.header(entry.getKey(), entry.getValue());
        }
    }

    /**
     * 獲取原請求頭
     */
    private Map<String, String> getHeaders(HttpServletRequest request) {
        Map<String, String> map = new LinkedHashMap<>();
        Enumeration<String> enumeration = request.getHeaderNames();
        if (enumeration != null) {
            while (enumeration.hasMoreElements()) {
                String key = enumeration.nextElement();
                String value = request.getHeader(key);
                map.put(key, value);
            }
        }
        return map;
    }
}