Spring Cloud Gateway 扩展支持多版本控制及灰度发布

第一反应，参考zuul 的实现，自定义断言，然后从上下中获取版本信息即可。但由于 spring cloud gateway 是基于webflux 的反应式编程，所以传统的TTL或者 RequestContextHolder 都不能正确的维护上下文请求。

先来看 spring clou的 gateway 默认的lb 策略实现 LoadBalancerClientFilter

public class LoadBalancerClientFilter implements GlobalFilter, Ordered { @Override public int getOrder() { return LOAD_BALANCER_CLIENT_FILTER_ORDER; } @Override @SuppressWarnings("Duplicates") public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) { return chain.filter(exchange); } protected ServiceInstance choose(ServerWebExchange exchange) { return loadBalancer.choose( ((URI) exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR)).getHost()); } }

我们只需要重写 choose 方法，把上下文请求传递到路由断言中即可，如下

@Override protected ServiceInstance choose(ServerWebExchange exchange) { HttpHeaders headers = exchange.getRequest().getHeaders(); return loadBalancer.choose(((URI) exchange.getAttribute(GATEWAY_REQUEST_URL_ATTR)).getHost(), headers); }

然后在路由断言中通过 PredicateKey获取到即可

public abstract class AbstractDiscoveryEnabledPredicate extends AbstractServerPredicate { /** * {@inheritDoc} */ @Override public boolean apply(@Nullable PredicateKey input) { return input != null && input.getServer() instanceof NacosServer && apply((NacosServer) input.getServer(), (HttpHeaders) input.getLoadBalancerKey()); } }

最后根据版本来计算

    public class GrayMetadataAwarePredicate extends AbstractDiscoveryEnabledPredicate { @Override protected boolean apply(NacosServer server, HttpHeaders headers) { PigxRibbonRuleProperties ribbonProperties = SpringContextHolder.getBean(PigxRibbonRuleProperties.class); if (!ribbonProperties.isGrayEnabled()) { log.debug("gray closed,GrayMetadataAwarePredicate return true"); return true; } final Map<String, String> metadata = server.getMetadata(); String version = metadata.get(CommonConstants.VERSION); // 判断Nacos服务是否有版本标签 if (StrUtil.isBlank(version)) { log.debug("nacos server tag is blank ,GrayMetadataAwarePredicate return true"); return true; } // 判断请求中是否有版本 String target = headers.getFirst(CommonConstants.VERSION); if (StrUtil.isBlank(target)) { log.debug("request headers version is blank,GrayMetadataAwarePredicate return true"); return true; } log.debug("请求版本:{} ,当前服务版本:{}", target, version); return target.equals(version); } }


参考：https://segmentfault.com/a/1190000019709733?utm_source=tag-newest