Rate-limit relating to the healthy servers count

[Thomas Hilaire]

Hi,

I want to implement a rate-limit system using the sticky table of 
HAProxy. Consider that I have 100 servers, and a limit of 10 requests 
per server, the ACL would be:

    http-request track-sc0 int(1) table GlobalRequestsTracker
    http-request deny deny_status 429 if { 
sc0_http_req_rate(GlobalRequestsTracker),div(100) gt 10 }

Now if I want to make this dynamic depending on the healthy servers 
count, I need to replace the hardcoded `100` per the `nbsrv` converter 
like this:

    http-request track-sc0 int(1) table GlobalRequestsTracker
    http-request deny deny_status 429 if { 
sc0_http_req_rate(GlobalRequestsTracker),div(nbsrv(MyBackend)) gt 10 }

But I'm getting the error:

    error detected while parsing an 'http-request deny' condition : 
invalid args in converter 'div' : expects an integer or a variable name 
in ACL expression 
'sc0_http_req_rate(GlobalRequestsTracker),div(nbsrv(MyBackend))'.

Is there a way to use `nbsrv` as a variable inside the `div` operator?

Thanks a lot!