利用spring-cloud-gateway怎么实现一个动态路由功能

线上项目发布一般有以下几种方案:

机发布
蓝绿部署
滚动部署
灰度发布

停机发布这种发布一般在夜里或者进行大版本升级的时候发布，因为需要停机，所以现在大家都在研究 Devops 方案。

蓝绿部署需要准备两个相同的环境。一个环境新版本，一个环境旧版本，通过负载均衡进行切换与回滚，目的是为了减少服务停止时间。

滚动部署就是在升级过程中，并不一下子启动所有新版本，是先启动一台新版本，再停止一台老版本，然后再启动一台新版本，再停止一台老版本，直到升级完成。基于 k8s 的升级方案默认就是滚动部署。

灰度发布也叫金丝雀发布，灰度发布中，常常按照用户设置路由权重，例如 90%的用户维持使用老版本，10%的用户尝鲜新版本。不同版本应用共存，经常与 A/B 测试一起使用，用于测试选择多种方案。

上边介绍的几种发布方案，主要是引出我们接下来介绍的 spring-cloud-gateway 动态路由，我们可以基于动态路由、负载均衡和策略加载去实现 灰度发布。当然现在有很多开源的框架可以实现 灰度发布，这里只是研究学习。

动态路由

spring-cloud-gateway 默认将路由加载在内存中。具体可以参见 InMemoryRouteDefinitionRepository 类的实现。

这里我们基于 Redis 实现动态路由。基础项目见 spring-cloud-gateway 简介

1. 将 actuator 的端点暴露出来。

management:endpoints:web:exposure:include: "*"

2. redis 配置

@Configuration
public class RedisConfig {@Bean(name = {"redisTemplate", "stringRedisTemplate"})public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory factory) {StringRedisTemplate redisTemplate = new StringRedisTemplate();redisTemplate.setConnectionFactory(factory);return redisTemplate;}}

3. 将原内存路由持久化到 redis

@Component
public class RedisRouteDefinitionRepository implements RouteDefinitionRepository {/*** hash存储的key*/public static final String GATEWAY_ROUTES = "gateway_dynamic_route";@Resourceprivate StringRedisTemplate redisTemplate;/*** 获取路由信息* @return*/@Overridepublic Flux<RouteDefinition> getRouteDefinitions() {List<RouteDefinition> routeDefinitions = new ArrayList<>();redisTemplate.opsForHash().values(GATEWAY_ROUTES).stream().forEach(routeDefinition -> routeDefinitions.add(JSON.parseObject(routeDefinition.toString(), RouteDefinition.class)));return Flux.fromIterable(routeDefinitions);}@Overridepublic Mono<Void> save(Mono<RouteDefinition> route) {return route.flatMap(routeDefinition -> {redisTemplate.opsForHash().put(GATEWAY_ROUTES, routeDefinition.getId(), JSONObject.toJSONString(routeDefinition));return Mono.empty();});}@Overridepublic Mono<Void> delete(Mono<String> routeId) {return routeId.flatMap(id -> {if (redisTemplate.opsForHash().hasKey(GATEWAY_ROUTES, id)) {redisTemplate.opsForHash().delete(GATEWAY_ROUTES, id);return Mono.empty();}return Mono.defer(() -> Mono.error(new NotFoundException("route definition is not found, routeId:" + routeId)));});}}

4. 重写动态路由服务

@Service
public class GatewayDynamicRouteService implements ApplicationEventPublisherAware {@Resourceprivate RedisRouteDefinitionRepository redisRouteDefinitionRepository;private ApplicationEventPublisher applicationEventPublisher;/*** 增加路由* @param routeDefinition* @return*/public int add(RouteDefinition routeDefinition) {redisRouteDefinitionRepository.save(Mono.just(routeDefinition)).subscribe();applicationEventPublisher.publishEvent(new RefreshRoutesEvent(this));return 1;}/*** 更新* @param routeDefinition* @return*/public int update(RouteDefinition routeDefinition) {redisRouteDefinitionRepository.delete(Mono.just(routeDefinition.getId()));redisRouteDefinitionRepository.save(Mono.just(routeDefinition)).subscribe();applicationEventPublisher.publishEvent(new RefreshRoutesEvent(this));return 1;}/*** 删除* @param id* @return*/public Mono<ResponseEntity<Object>> delete(String id) {return redisRouteDefinitionRepository.delete(Mono.just(id)).then(Mono.defer(() -> Mono.just(ResponseEntity.ok().build()))).onErrorResume(t -> t instanceof NotFoundException, t -> Mono.just(ResponseEntity.notFound().build()));}@Overridepublic void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {this.applicationEventPublisher = applicationEventPublisher;}
}

5. 对外暴露接口

@RestController
@RequestMapping("/gateway")
public class GatewayDynamicRouteController {@Resourceprivate GatewayDynamicRouteService gatewayDynamicRouteService;@PostMapping("/add")public String create(@RequestBody RouteDefinition entity) {int result = gatewayDynamicRouteService.add(entity);return String.valueOf(result);}@PostMapping("/update")public String update(@RequestBody RouteDefinition entity) {int result = gatewayDynamicRouteService.update(entity);return String.valueOf(result);}@DeleteMapping("/delete/{id}")public Mono<ResponseEntity<Object>> delete(@PathVariable String id) {return gatewayDynamicRouteService.delete(id);}}

测试

测试前删除我们配置的静态路由，因为静态路由和 redis 动态路由同时存在时取并集。

访问 http://localhost:2000/actuator/gateway/routes , 可以看到只有默认路由。

[{"route_id": "CompositeDiscoveryClient_consul","route_definition": {"id": "CompositeDiscoveryClient_consul","predicates": [{"name": "Path","args": {"pattern": "/consul/**"}}],"filters": [{"name": "RewritePath","args": {"regexp": "/consul/(?<remaining>.*)","replacement": "/${remaining}"}}],"uri": "lb://consul","order": 0},"order": 0},{"route_id": "CompositeDiscoveryClient_idc-gateway","route_definition": {"id": "CompositeDiscoveryClient_idc-gateway","predicates": [{"name": "Path","args": {"pattern": "/idc-gateway/**"}}],"filters": [{"name": "RewritePath","args": {"regexp": "/idc-gateway/(?<remaining>.*)","replacement": "/${remaining}"}}],"uri": "lb://idc-gateway","order": 0},"order": 0},{"route_id": "CompositeDiscoveryClient_idc-provider1","route_definition": {"id": "CompositeDiscoveryClient_idc-provider1","predicates": [{"name": "Path","args": {"pattern": "/idc-provider1/**"}}],"filters": [{"name": "RewritePath","args": {"regexp": "/idc-provider1/(?<remaining>.*)","replacement": "/${remaining}"}}],"uri": "lb://idc-provider1","order": 0},"order": 0},{"route_id": "CompositeDiscoveryClient_idc-provider2","route_definition": {"id": "CompositeDiscoveryClient_idc-provider2","predicates": [{"name": "Path","args": {"pattern": "/idc-provider2/**"}}],"filters": [{"name": "RewritePath","args": {"regexp": "/idc-provider2/(?<remaining>.*)","replacement": "/${remaining}"}}],"uri": "lb://idc-provider2","order": 0},"order": 0}
]

这个时候访问 http://192.168.124.5:2000/idc-provider1/provider1/1 根据结果可以推测能正确路由到 provider1，测试结果一致。

创建 provider1 路由，将路径设置为 /p1/**，测试是否生效。

POST 请求 http://localhost:2000/gateway/add

{"id":"provider1","predicates":[{"name":"Path","args":{"_genkey_0":"/p1/**"}},{"name":"RemoteAddr","args":{"_genkey_0":"192.168.124.5/16"}}],"filters":[{"name":"StripPrefix","args":{"_genkey_0":"1"}}],"uri":"lb://idc-provider1","order":0
}

查看 redis 存储，或者请求 http://localhost:2000/actuator/gateway/routes , 都可以看到配置成功。

访问

curl http://localhost:2000/p1/provider1/1

结果输出 2001，与期望一致。