详解Spring Cloud Gateway 限流操作

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

@Bean
public KeyResolver ipKeyResolver() {
 return exchange -> Mono.just(exchange.getRequest().getRemoteAddress().getHostName());
}

@Bean
KeyResolver userKeyResolver() {
 return exchange -> Mono.just(exchange.getRequest().getQueryParams().getFirst("userId"));
}

@Bean
KeyResolver apiKeyResolver() {
 return exchange -> Mono.just(exchange.getRequest().getPath().value());
}

server:
 port: 8084
spring:
 redis:
 host: 127.0.0.1
 port: 6379
 cloud:
 gateway:
  routes:
  - id: fsh-house
  uri: lb://fsh-house
  predicates:
  - Path=/house/**
  filters:
  - name: RequestRateLimiter
   args:
   redis-rate-limiter.replenishRate: 10
   redis-rate-limiter.burstCapacity: 20
   key-resolver: "#{@ipKeyResolver}"

// routeId也就是我们的fsh-house，id就是限流的key，也就是localhost。
public Mono<Response> isAllowed(String routeId, String id) {
 // 会判断RedisRateLimiter是否初始化了
 if (!this.initialized.get()) {
  throw new IllegalStateException("RedisRateLimiter is not initialized");
 }
 // 获取routeId对应的限流配置
 Config routeConfig = getConfig().getOrDefault(routeId, defaultConfig);

 if (routeConfig == null) {
  throw new IllegalArgumentException("No Configuration found for route " + routeId);
 }

 // 允许用户每秒做多少次请求
 int replenishRate = routeConfig.getReplenishRate();

 // 令牌桶的容量，允许在一秒钟内完成的最大请求数
 int burstCapacity = routeConfig.getBurstCapacity();

 try {
  // 限流key的名称（request_rate_limiter.{localhost}.timestamp，request_rate_limiter.{localhost}.tokens）
  List<String> keys = getKeys(id);


  // The arguments to the LUA script. time() returns unixtime in seconds.
  List<String> scriptArgs = Arrays.asList(replenishRate + "", burstCapacity + "",
    Instant.now().getEpochSecond() + "", "1");
  // allowed, tokens_left = redis.eval(SCRIPT, keys, args)
  // 执行LUA脚本
  Flux<List<Long>> flux = this.redisTemplate.execute(this.script, keys, scriptArgs);
    // .log("redisratelimiter", Level.FINER);
  return flux.onErrorResume(throwable -> Flux.just(Arrays.asList(1L, -1L)))
    .reduce(new ArrayList<Long>(), (longs, l) -> {
     longs.addAll(l);
     return longs;
    }) .map(results -> {
     boolean allowed = results.get(0) == 1L;
     Long tokensLeft = results.get(1);

     Response response = new Response(allowed, getHeaders(routeConfig, tokensLeft));

     if (log.isDebugEnabled()) {
      log.debug("response: " + response);
     }
     return response;
    });
 }
 catch (Exception e) {
  log.error("Error determining if user allowed from redis", e);
 }
 return Mono.just(new Response(true, getHeaders(routeConfig, -1L)));
}

local tokens_key = KEYS[1]
local timestamp_key = KEYS[2]
--redis.log(redis.LOG_WARNING, "tokens_key " .. tokens_key)

local rate = tonumber(ARGV[1])
local capacity = tonumber(ARGV[2])
local now = tonumber(ARGV[3])
local requested = tonumber(ARGV[4])

local fill_time = capacity/rate
local ttl = math.floor(fill_time*2)

--redis.log(redis.LOG_WARNING, "rate " .. ARGV[1])
--redis.log(redis.LOG_WARNING, "capacity " .. ARGV[2])
--redis.log(redis.LOG_WARNING, "now " .. ARGV[3])
--redis.log(redis.LOG_WARNING, "requested " .. ARGV[4])
--redis.log(redis.LOG_WARNING, "filltime " .. fill_time)
--redis.log(redis.LOG_WARNING, "ttl " .. ttl)

local last_tokens = tonumber(redis.call("get", tokens_key))
if last_tokens == nil then
 last_tokens = capacity
end
--redis.log(redis.LOG_WARNING, "last_tokens " .. last_tokens)

local last_refreshed = tonumber(redis.call("get", timestamp_key))
if last_refreshed == nil then
 last_refreshed = 0
end
--redis.log(redis.LOG_WARNING, "last_refreshed " .. last_refreshed)

local delta = math.max(0, now-last_refreshed)
local filled_tokens = math.min(capacity, last_tokens+(delta*rate))
local allowed = filled_tokens >= requested
local new_tokens = filled_tokens
local allowed_num = 0
if allowed then
 new_tokens = filled_tokens - requested
 allowed_num = 1
end

--redis.log(redis.LOG_WARNING, "delta " .. delta)
--redis.log(redis.LOG_WARNING, "filled_tokens " .. filled_tokens)
--redis.log(redis.LOG_WARNING, "allowed_num " .. allowed_num)
--redis.log(redis.LOG_WARNING, "new_tokens " .. new_tokens)

redis.call("setex", tokens_key, ttl, new_tokens)
redis.call("setex", timestamp_key, ttl, now)

return { allowed_num, new_tokens }