Spring Cloud Gateway的动态路由的简单实现方式

1.前言

网关中有两个重要的概念，那就是路由配置和路由规则，路由配置是指配置某请求路径路由到指定的目的地址。而路由规则是指匹配到路由配置之后，再根据路由规则进行转发处理。 Spring Cloud Gateway作为所有请求流量的入口，在实际生产环境中为了保证高可靠和高可用，尽量避免重启,需要实现Spring Cloud Gateway动态路由配置。前面章节介绍了Spring Cloud Gateway提供的两种方法去配置路由规则，但都是在Spring Cloud Gateway启动时候，就将路由配置和规则加载到内存里，无法做到不重启网关就可以动态的对应路由的配置和规则进行增加，修改和删除。`本篇文章简单介绍如何实现Spring Cloud Gateway的动态路由。

2. Spring Cloud Gateway简单的动态路由实现

Spring Cloud Gateway的官方文档并没有讲如何动态配置，查看 Spring Cloud Gateway的源码，发现在org.springframework.cloud.gateway.actuate.GatewayControllerEndpoint类中提供了动态配置的Rest接口，但是需要开启Gateway的端点，而且提供的功能不是很强大。通过参考和GatewayControllerEndpoint相关的代码，可以自己编码实际动态路由配置。下面通过案例的方式去讲解怎么实现Gateway的动态路由配置。案例工程如ch18-7-gateway所示。

代码地址:https://github.com/SpringCloud/spring-cloud-code/blob/master/ch18-7/ch18-7-gateway

3. 简单动态路由的实现

3.1 新建Maven工程ch18-7-gateway

配置主要的核心依赖如代码清单18-33所示：代码清单: ch18-7/ch18-7-gateway/pom.xml

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-actuator</artifactId>
    </dependency>
</dependencies>

3.2 根据Spring Cloud Gateway的路由模型定义数据传输模型

分别创建GatewayRouteDefinition.java, GatewayPredicateDefinition.java, GatewayFilterDefinition.java这三个类。 (1) 创建路由定义模型如下代码清单18-34所示：代码清单 18-34: ch18-7/ch18-7-gateway/src/main/java/cn/springcloud/book/gateway/model/GatewayRouteDefinition.java

public class GatewayRouteDefinition {
    //路由的Id
    private String id;
    //路由断言集合配置
    private List<GatewayPredicateDefinition> predicates = new ArrayList<>();
    //路由过滤器集合配置
    private List<GatewayFilterDefinition> filters = new ArrayList<>();
    //路由规则转发的目标uri
    private String uri;
    //路由执行的顺序
    private int order = 0;
    //此处省略get和set方法
}

(2)创建过滤器定义模型,代码如代码清单18-35所示：代码清单18-35: ch18-7/ch18-7-gateway/src/main/java/cn/springcloud/book/gateway/model/GatewayFilterDefinition.java

public class GatewayFilterDefinition {
    //Filter Name
    private String name;
    //对应的路由规则
    private Map<String, String> args = new LinkedHashMap<>();
    //此处省略Get和Set方法
}

(3)路由断言定义模型，代码如代码清单18-36所示: 代码清单18-36: ch18-7/ch18-7-gateway/src/main/java/cn/springcloud/book/gateway/model/GatewayPredicateDefinition.java

public class GatewayPredicateDefinition {
    //断言对应的Name
    private String name;
    //配置的断言规则
    private Map<String, String> args = new LinkedHashMap<>();
    //此处省略Get和Set方法
}

3.3 编写动态路由实现类

编写DynamicRouteServiceImpl并实现ApplicationEventPublisherAware接口，代码如代码清单18-37所示: ch18-37/ch18-7-gateway/src/main/java/cn/springcloud/book/gateway/route/DynamicRouteServiceImpl.java

@Service
public class DynamicRouteServiceImpl implements ApplicationEventPublisherAware {
    @Autowired
    private RouteDefinitionWriter routeDefinitionWriter;
    private ApplicationEventPublisher publisher;
    //增加路由
    public String add(RouteDefinition definition) {
        routeDefinitionWriter.save(Mono.just(definition)).subscribe();
        this.publisher.publishEvent(new RefreshRoutesEvent(this));
        return "success";
    }
    //更新路由
    public String update(RouteDefinition definition) {
        try {
            this.routeDefinitionWriter.delete(Mono.just(definition.getId()));
        } catch (Exception e) {
            return "update fail,not find route  routeId: "+definition.getId();
        }
        try {
            routeDefinitionWriter.save(Mono.just(definition)).subscribe();
            this.publisher.publishEvent(new RefreshRoutesEvent(this));
            return "success";
        } catch (Exception e) {
            return "update route  fail";
        }
    }
    //删除路由
    public Mono<ResponseEntity<Object>> delete(String id) {
        return this.routeDefinitionWriter.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.publisher = applicationEventPublisher;
    }
}

3.4 编写Rest接口

编写RouteController类的提供Rest接口，用于动态路由配置。代码如代码清单18-38所示: 代码清单 18-38: ch18-7/ch18-7-gateway/src/main/java/cn/springcloud/book/gateway/controller/RouteController.java

@RestController
@RequestMapping("/route")
public class RouteController {
    @Autowired
    private DynamicRouteServiceImpl dynamicRouteService;
    //增加路由
    @PostMapping("/add")
    public String add(@RequestBody GatewayRouteDefinition gwdefinition) {
        try {
            RouteDefinition definition = assembleRouteDefinition(gwdefinition);
            return this.dynamicRouteService.add(definition);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "succss";
    }
    
    //删除路由
    @DeleteMapping("/routes/{id}")
    public Mono<ResponseEntity<Object>> delete(@PathVariable String id) {
        return this.dynamicRouteService.delete(id);
    }
    //更新路由
    @PostMapping("/update")
    public String update(@RequestBody GatewayRouteDefinition gwdefinition) {
        RouteDefinition definition = assembleRouteDefinition(gwdefinition);
        return this.dynamicRouteService.update(definition);
    }
}

3.5 配置application.yml文件

在application.yml文件配置应用的配置信息，并开启Spring Cloud Gateway对外提供的端点Rest接口。代码如代码清单18-39所示: 代码清单 18-39: ch18-7/ch18-7-gateway/src/main/resources/application.yml 配置输出日志如下所示:

# 配置输出日志
logging:
  level:
    org.springframework.cloud.gateway: TRACE
    org.springframework.http.server.reactive: DEBUG
    org.springframework.web.reactive: DEBUG
    reactor.ipc.netty: DEBUG
#开启端点
management:
  endpoints:
    web:
      exposure:
        include: '*'
  security:
    enabled: false