spring-cloud-gateway動態路由

概述

線上項目發布一般有以下幾種方案:

1. 停機發布
2. 藍綠部署
3. 滾動部署
4. 灰度發布

停機發布 這種發布一般在夜里或者進行大版本升級的時候發布，因為需要停機，所以現在大家都在研究 Devops 方案。

藍綠部署 需要准備兩個相同的環境。一個環境新版本，一個環境舊版本，通過負載均衡進行切換與回滾，目的是為了減少服務停止時間。

滾動部署 就是在升級過程中，並不一下子啟動所有新版本，是先啟動一台新版本，再停止一台老版本，然后再啟動一台新版本，再停止一台老版本，直到升級完成。基於 k8s 的升級方案默認就是滾動部署。

灰度發布 也叫金絲雀發布，灰度發布中，常常按照用戶設置路由權重，例如 90%的用戶維持使用老版本，10%的用戶嘗鮮新版本。不同版本應用共存，經常與 A/B 測試一起使用，用於測試選擇多種方案。

上邊介紹的幾種發布方案，主要是引出我們接下來介紹的 spring-cloud-gateway 動態路由，我們可以基於動態路由、負載均衡和策略加載去實現 灰度發布。當然現在有很多開源的框架可以實現 灰度發布，這里只是研究學習。

動態路由

spring-cloud-gateway 默認將路由加載在內存中。具體可以參見 InMemoryRouteDefinitionRepository 類的實現。

這里我們基於 Redis 實現動態路由。基礎項目見 spring-cloud-gateway 簡介

1. 將 actuator 的端點暴露出來。

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. 將原內存路由持久化到 redis

@Component
public class RedisRouteDefinitionRepository implements RouteDefinitionRepository {

    /**
     * hash存儲的key
     */
    public static final String GATEWAY_ROUTES = "gateway_dynamic_route";

    @Resource
    private StringRedisTemplate redisTemplate;

    /**
     * 獲取路由信息
     * @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. 重寫動態路由服務

@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;
    }

    /**
     * 刪除
     * @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. 對外暴露接口

@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);
    }

}

測試

測試前刪除我們配置的靜態路由，因為靜態路由和 redis 動態路由同時存在時取並集。

1. 訪問 http://localhost:2000/actuator/gateway/routes , 可以看到只有默認路由。

[
    {
        "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
    }
]

這個時候訪問 http://192.168.124.5:2000/idc-provider1/provider1/1 根據結果可以推測能正確路由到 provider1， 測試結果一致。

2. 創建 provider1 路由，將路徑設置為 /p1/**，測試是否生效。

POST 請求 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 存儲，或者請求 http://localhost:2000/actuator/gateway/routes , 都可以看到配置成功。

訪問

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

結果輸出 2001，與期望一致。

由此可見動態路由已經生效。

結語

本文到此結束。感興趣的小伙伴后續可以通過加載配置文件，基於權重進行灰度。歡迎大家關注公眾號【當我遇上你】。