Spring Cloud Gateway中的分布式限流

我们在开发系统的时候可能会有对系统进行限流的需求，Spring Cloud Gateway有自带限流的方案，Spring Cloud Gateway中提供了一个RequestRateLimiterGatewayFilterFactory。这种限流方式使用到了Redis， 先添加Redis的依赖：

<dependencies>
    <!-- Spring Cloud Gateway的依赖-->
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis-reactive</artifactId>
    </dependency>
</dependencies>

配置如下：

import org.springframework.cloud.gateway.filter.ratelimit.KeyResolver;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

public class RemoteAddrKeyResolver implements KeyResolver {

    public static final String BEAN_NAME = "remoteAddrKeyResolver";

    @Override
    public Mono<String> resolve(ServerWebExchange exchange) {
        return Mono.just(exchange.getRequest().getRemoteAddress().getAddress().getHostAddress());
    }

}

@Configuration
public class RemoteKeyResolver {

    @Bean(name = RemoteAddrKeyResolver.BEAN_NAME)
    public RemoteAddrKeyResolver remoteAddrKeyResolver() {
        return new RemoteAddrKeyResolver();
    }
}

在此我们是根据ip地址限流的：

Mono<String> just = Mono.just(exchange.getRequest().getRemoteAddress().getAddress().getHostAddress());

application.yml配置文件配置如下：

spring:
  application:
    name: ok-cloud-gateway
  redis:
      host: localhost
      port: 6379
  cloud:
    gateway:
      routes:
        - id: rateLimit_route
          uri: http://localhost:8000/hello/rateLimit
          order: 0
          predicates:
            - Path=/test/rateLimit
          filters:
            #filter名称必须是RequestRateLimiter
            - name: RequestRateLimiter
              args:
                #使用SpEL按名称引用bean
                key-resolver: "#{@remoteAddrKeyResolver}"
                #允许用户每秒处理多少个请求
                redis-rate-limiter.replenishRate: 1
                #令牌桶的容量，允许在一秒钟内完成的最大请求数
                redis-rate-limiter.burstCapacity: 5

spring:
  application:
    name: gateway-service
#  redis:
#    database: 0
#    host: localhost
#    port: 6379
#    password:
#    timeout: 1000ms
#    lettuce:
#      pool:
#        max-active: 8
#        max-idle: 8
#        min-idle: 1
#        max-wait: 1000ms
#  cache:
#    type: REDIS
  cloud:
    gateway:
      discovery:
        locator:
          enabled: true
      routes:
        - id: order
          uri: lb://order-service
          predicates:
          - Path=/api/order-service/**
          filters:
          - StripPrefix=1
          - name: RequestRateLimiter
            args:
              key-resolver: '#{@remoteAddrKeyResolver}'
              redis-rate-limiter.replenishRate: 1
              redis-rate-limiter.burstCapacity: 2

上面贴出的是完整的Spring Cloud Gateway的配置，主要配置为filters下的RequestRateLimiter，key-resolver表示使用名为remoteAddrKeyResolver的限流配置配置类，此限流方式采用的是令牌桶算法的限流方式

• redis-rate-limiter.replenishRate：令牌桶每秒填充平均速率
• redis-rate-limiter.burstCapacity: 令牌桶的总容量