Spring Cloud Gateway实现灰度发布方案

  - id: user-route
      uri: lb://user-login
      predicates:
        - Path=/user/**

  - id: user-route-gray
      uri: lb://user-login
      predicates:
        - Path=/user/**
        - HeaderUsername=Jack

@Component
public class HeaderUsernameRoutePredicateFactory extends AbstractRoutePredicateFactory<HeaderUsernameRoutePredicateFactory.Config> {

    public static final String USERNAME = "Username";

    public HeaderUsernameRoutePredicateFactory() {
        super(Config.class);
    }

    @Override
    public ShortcutType shortcutType() {
        return ShortcutType.GATHER_LIST;
    }

    @Override
    public List<String> shortcutFieldOrder() {
        return Collections.singletonList("username");
    }

    @Override
    public Predicate<ServerWebExchange> apply(Config config) {
        List<String> usernames = config.getUsername();
        return new GatewayPredicate() {
            @Override
            public boolean test(ServerWebExchange serverWebExchange) {
                String username = serverWebExchange.getRequest().getHeaders().getFirst(USERNAME);
                if (!StringUtils.isEmpty(username)) {
                    return usernames.contains(username);
                }
                return false;
            }

            @Override
            public String toString() {
                return String.format("Header: Username=%s", config.getUsername());
            }
        };
    }

    @NoArgsConstructor
    @Getter
    @Setter
    @ToString
    public static class Config {
        private List<String> username;
    }
}

@Slf4j
public class GrayRoundRobinLoadBalancer implements ReactorServiceInstanceLoadBalancer {

	private static final position = new AtomicInteger(new Random().nextInt(1000));
    private final ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider;
    private final String serviceId;
    private final AtomicInteger position;

    public GrayRoundRobinLoadBalancer(ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, String serviceId) {
        this.serviceId = serviceId;
        this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider;
    }

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

    private Response<ServiceInstance> getInstanceResponse(List<ServiceInstance> instances, HttpHeaders headers) {
        List<ServiceInstance> serviceInstances = instances.stream()
                .filter(instance -> {
                    //根据请求头中的版本号信息，选取注册中心中的相应服务实例
                    String version = headers.getFirst("Version");
                    if (version != null) {
                        return version.equals(instance.getMetadata().get("version"));
                    } else {
                        return true;
                    }
                }).collect(Collectors.toList());
        if (serviceInstances.isEmpty()) {
            if (log.isWarnEnabled()) {
                log.warn("No servers available for service: " + serviceId);
            }
            return new EmptyResponse();
        }
        int pos = Math.abs(this.position.incrementAndGet());
        ServiceInstance instance = serviceInstances.get(pos % serviceInstances.size());
        return new DefaultResponse(instance);
    }
}

@Slf4j
@Component
public class GrayReactiveLoadBalancerClientFilter implements GlobalFilter, Ordered {

    private static final int LOAD_BALANCER_CLIENT_FILTER_ORDER = 10150;

    private final LoadBalancerClientFactory clientFactory;

    public GrayReactiveLoadBalancerClientFilter(LoadBalancerClientFactory clientFactory) {
        this.clientFactory = clientFactory;
    }

    @Override
    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 && ("grayLb".equals(url.getScheme()) || "grayLb".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(true, "Unable to find instance for " + url.getHost());
                } else {
                    URI uri = exchange.getRequest().getURI();
                    String overrideScheme = null;
                    if (schemePrefix != null) {
                        overrideScheme = url.getScheme();
                    }

                    DelegatingServiceInstance serviceInstance = new DelegatingServiceInstance((ServiceInstance) response.getServer(), overrideScheme);
                    URI requestUrl = this.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 = (URI) exchange.getAttribute(ServerWebExchangeUtils.GATEWAY_REQUEST_URL_ATTR);
        GrayRoundRobinLoadBalancer loadBalancer = new GrayRoundRobinLoadBalancer(clientFactory.getLazyProvider(uri.getHost(), ServiceInstanceListSupplier.class), uri.getHost());
        return loadBalancer.choose(this.createRequest(exchange));
    }

    private Request createRequest(ServerWebExchange exchange) {
        HttpHeaders headers = exchange.getRequest().getHeaders();
        return new DefaultRequest<>(headers);
    }

    protected URI reconstructURI(ServiceInstance serviceInstance, URI original) {
        return LoadBalancerUriTools.reconstructURI(serviceInstance, original);
    }

    @Override
    public int getOrder() {
        return LOAD_BALANCER_CLIENT_FILTER_ORDER;
    }
}

 - id: user-route-gray
      uri: grayLb://user-login
      predicates:
        - Path=/user/**
        - HeaderUsername=Jack
      filters:
        - AddRequestHeader=Version,v2
 - id: user-route
      uri: grayLb://user-login
      predicates:
        - Path=/user/**
      filters:
        - AddRequestHeader=Version,v1