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Zdenda's avatar
Zdenda
Icon for Cirrus rankCirrus
Apr 19, 2013

Local variable used in more iRules but in one VIP - is it shared among VIP iRules?

Hi,

 

I am thinking about using variable in the way - when I enable some action (redirect), then another actions (another redirects) in another rules will be disabled.

 

All these are using different iRules, but they are attached to the same VIP.

 

 

I was thinking about static variable, but now it seems that it could work also with simple local variable because it is shared within the session?

 

Am I right? Please comment who knows more, thank you a lot..

 

 

Zdenek

 

application delivery
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  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Apr 19, 2013
    When multiple iRules are applied to a virtual server their events are combined, sometimes in an order that you didn't intend. The first thing I would recommend is using the priority tag in the event declarations to guarantee order. As for using a single local variable across iRules, in the same VIP, yes it should work but it's probably not the safest thing to do. If you're going to do this, I highly recommend that you apply [info exists ] checks and catch clauses where appropriate.
  • Zdenda's avatar
    Zdenda
    Icon for Cirrus rankCirrus
    Apr 19, 2013

    Sorry, but could you paste some example please? I am not sure how I should appy that [ info exists]?

     

    Thanks,

     

    Zdenek

     

  • What_Lies_Bene1's avatar
    What_Lies_Bene1
    Icon for Cirrostratus rankCirrostratus
    Apr 19, 2013
    Here's an example of checking that a variable exists; 

    
if { [info exists lookup] and $lookup == 1 } { ...
Note no $ symbol is used for the variable name with info as you are not referencing the variable value