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Patrik_Jonsson's avatar
Patrik_Jonsson
Icon for MVP rankMVP
Nov 20, 2013

Throttle incoming requests per minute

Hi Guys! Trying to write an iRule that throttles incoming requests but I can't get this very simple example to work. Basically my problem seems to be that the global connections variable never is being reset.

Also, I'm not sure if I have to use a global variable in this case. The limit should only affect one particular VIP and the iRule is only used at this VIP.

Throttle number of requests per minute
when RULE_INIT {
    array set connections { }
        after 60000 -periodic {
            array set ::connections { }
        }
    }

when HTTP_REQUEST {
    if { [info exists ::connections([IP::client_addr])] } {
        if { [incr ::connections([IP::client_addr])] > 10 } {
            HTTP::respond 200 content "You have passed the request threshold of 10/minute."
            set blocked 1
        } 
    } else {
        set ::connections([IP::client_addr]) 1
        HTTP::respond 200 content "OK"
    }
}

Thankful for any advice!

Kind regards, Patrik

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4 Replies

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  • IheartF5_45022's avatar
    IheartF5_45022
    Icon for Nacreous rankNacreous
    Nov 20, 2013

    You should definitely use the "table" command to access the session table for this. The data expiration feature is made for this use-case. Look [here] (https://devcentral.f5.com/articles/v101-the-table-command-the-basics)

     

    Joanna

     

  • IheartF5_45022's avatar
    IheartF5_45022
    Icon for Nacreous rankNacreous
    Nov 20, 2013

    In case you don't have your answer yet, the 'table' is global which is one of the other reasons it's awesome.

     

  • Patrik_Jonsson's avatar
    Patrik_Jonsson
    Icon for MVP rankMVP
    Nov 21, 2013

    Here's the sample rule I wrote to test the tables in case anyone else has the same issue.

    Throttle number of requests per minute
when HTTP_REQUEST {

    table add [IP::client_addr] 1 indefinite 10
    if { [table incr [IP::client_addr]] > 4 } {

        HTTP::respond 200 content "Too many"

    } else {
        HTTP::respond 200 content "OK"

    }
}
  • IheartF5_45022's avatar
    IheartF5_45022
    Icon for Nacreous rankNacreous
    Nov 21, 2013

    I don't think you need the "table add" statement. Just use "table incr" which will add key to the table with value 1 if it doesn't exist, and incr it by 1 if it does exist.