spring-cloud-gateway动态路由的实现方法

概述

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";

  @Resource
  private StringRedisTemplate redisTemplate;

  /**
   * 获取路由信息
   * @return
   */
  @Override
  public Flux getRouteDefinitions() {
    List 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 save(Mono route) {
    return route.flatMap(routeDefinition -> {
      redisTemplate.opsForHash().put(GATEWAY_ROUTES, routeDefinition.getId(), JSONObject.toJSONString(routeDefinition));
      return Mono.empty();
    });
  }

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

由此可见动态路由已经生效。

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