10(limit) / 1(delta) = 60秒間に600件以上同じIPアドレスからリクエストがきたら、 PenaltyBoxにentryの値が入る
unset req.http.x-penalized;
set req.http.x-penalized = ratelimit.check_rate(
req.http.Fastly-Client-IP, # entry
rc, # Rate Counter to be used
1, # delta
60, # window
10, # limit
pb, # Penalty Box to be used
1m # The penalty box. must be between 1m to 1h
);