Migration of gist:4293859

gistfile1.scala

def rateLimit(action: => String, subject: => String, maxRequests: => Int): Directive0 = {
  mapInnerRoute {
    inner => ctx =>
      val key = action + ":" + subject

      add(redis, key)
      val actionCount = count(redis, key, interval)

      if (actionCount >= maxRequests) {
        logger.warn("Rate limiting user '" + subject + "': exceeded max number of requests (" + maxRequests + ").")
        ctx.reject(AuthorizationFailedRejection)
      }
      else inner(ctx.mapHttpResponseHeaders(
        headers =>
        // Number of requests allowed for that IP address per interval
          RawHeader("X-FeatureRateLimit-Limit", maxRequests.toString) ::
            // Number of seconds in the rate limit interval
            RawHeader("X-FeatureRateLimit-IntervalSecs", interval.toString) ::
            // Number of requests remaining.
            RawHeader("X-FeatureRateLimit-Remaining", "" + (maxRequests - actionCount)) ::
            // Time at which your quota is reset, in Unix epoch time
            RawHeader("X-FeatureRateLimit-Reset", "" + (System.currentTimeMillis() + (redis.withClient(client => client.ttl(key).getOrElse(0l) * 1000)))) ::
            headers
      ))
  }
}