Hi Krishna, Krishna Kumar (Engineering) wrote: > Thanks for your response. However, I want to restrict the requests > per second either at the frontend or backend, not session rate. I > may have only 10 connections from clients, but the backends can > handle only 100 RPS. How do I deny or delay requests when they > cross a limit?
A "session" is this context is equivalent to a request-response pair. It is not connected to a session of your applciation which might be represented by a session cookie. As such, to restrict the number of requests per second for a frontend, rate-limit sessions is exactly the option you are looking for. It does not limit the concurrent number of sessions (as maxconn would do) but the rate with which the requests are comming in. If there are more requests per second than the configured value, haproxy waits until the session rate drops below the configured value. Once the socket's backlog backlog is full, requests will not be accepted by the kernel anymore until it clears. If you want to deny requsts with a custom http error instead, you could use a custom `http-request deny` rule and use the fe_sess_rate or be_sess_rate values. Cheers, Holger
