spring-cloud-gateway动态路由

概述

线上项目发布一般有以下几种方案:

1. 停机发布
2. 蓝绿部署
3. 滚动部署
4. 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";

    @Resource
    private StringRedisTemplate redisTemplate;

    /**
     * 获取路由信息
     * @return
     */
    @Override
    public 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);
    }

    @Override
    public Mono<Void> save(Mono<RouteDefinition> route) {
        return route.flatMap(routeDefinition -> {
            redisTemplate.opsForHash().put(GATEWAY_ROUTES, routeDefinition.getId(), JSONObject.toJSONString(routeDefinition));
            return Mono.empty();
        });
    }

    @Override
    public 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 {

    @Resource
    private 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()));
    }


    @Override
    public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
        this.applicationEventPublisher = applicationEventPublisher;
    }
}

5. 对外暴露接口

@RestController
@RequestMapping("/gateway")
public class GatewayDynamicRouteController {

    @Resource
    private 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。

1. 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。

2. 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。

由此可见动态路由已经生效。

结语

本文到此结束。感兴趣的小伙伴后续可以通过加载配置文件，基于权重进行灰度。欢迎大家关注公众号【当我遇上你】。