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Ravi_Rajan_7549's avatar
Ravi_Rajan_7549
Icon for Nimbostratus rankNimbostratus
Mar 17, 2008

Redirection with Multiple pools

Hi,

 

 

I am not very experienced with irules and have few queries as below -

 

 

I have two pools ex. poola and poolb. Each pool has few servers like -

 

 

poola - server1, server2

 

poolb - server3, server4.

 

 

Server1 & Server2 -

 

These servers are hosting web applications with URI - /abc and /xyz

 

 

Server3 & Server4-

 

 

These servers are hosting web applications with URI /pqr and /def

 

 

Now i have a single virtual server and i need an irule which does something like this -

 

 

For each incoming request, the irule should check the URI and based on URI, it should use the appropriate pool.

 

 

For ex - In case URI is /abc, then the virtual server should poola and If URI is /def then the virtual server should use poolb.

 

 

TIA,

 

 

Regards,

 

Ravi

 

application delivery
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devops
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14 Replies

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  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Mar 17, 2008
    Hi Ravi

     

     

    The code could look something like the following:

     

     

    
when HTTP_REQUEST {
    switch [HTTP::uri]
     "/abc" - "/xyz" { pool poola }
     "/pqr" - "/def" { pool poolb }
    }
}

     

     

     

    Keep in mind that the code can be written in IF-ELSE logic, but switch statement will look a bit cleaner for this particular situation.

     

     

    You can learn more about switch statements from the following link

     

     

    http://devcentral.f5.com/Default.aspx?tabid=63&articleType=ArticleView&articleId=129

     

     

    thanks,

     

    CB
  • Ravi_Rajan_7549's avatar
    Ravi_Rajan_7549
    Icon for Nimbostratus rankNimbostratus
    Mar 17, 2008
    Hi,

     

     

    Thanks for the below. One more addition to the above, is that there may be some applications which i would like to go with the default pool itself.

     

     

    Also, can we use datagroups instead ?

     

     

    Thanks,

     

    Ravi
  • The_Bhattman's avatar
    The_Bhattman
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    Mar 17, 2008
    There is a setting in the pool configuration where you can select the default pool. If the irules fail or it doesn't select the pool the default pool is choosen.

     

     

    Yes You can also use datagroups with an if argument.

     

     

    /CB

     

  • Ravi_Rajan_7549's avatar
    Ravi_Rajan_7549
    Icon for Nimbostratus rankNimbostratus
    Mar 17, 2008
    Hi,

     

     

    Thanks. As i am new to irules, it would be helpful if you can give a sample code using datagroups where in datagroup1 will have /abc & /xyz and datagroup2 will have /pqr & /def. Also, instead of [HTTP::uri], would like to use - string tolower [HTTP::uri]

     

     

    TIA,

     

     

    Ravi
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Mar 17, 2008
    The class object can be defined in the following

    
class dg_poola {
"/abc"
"/xyz"
}
class dg_poolb {
"/prq"
"/def"
}

    The irule can be written so it uses the datagroup along with 'string tolower' argument.

    
when HTTP_REQUEST {    
        if { [matchclass [string tolower [HTTP::uri]] contains $::dg_poola] } {
          pool poola 
        } else if { [matchclass [string tolower [HTTP::uri]] contains $::dg_poolb] } {
          pool poolb 
        }
      }
}

    /cb
  • Ravi_Rajan_7549's avatar
    Ravi_Rajan_7549
    Icon for Nimbostratus rankNimbostratus
    Mar 18, 2008
    Hi,

     

     

    Thanks for the below. I will test it out.

     

     

    In case of huge number of pools, can this be rewritten with a switch statement ?

     

     

    Regards,

     

    Ravi
  • Nicolas_Menant's avatar
    Nicolas_Menant
    Icon for Employee rankEmployee
    Mar 18, 2008
    Hi,

     

     

    in case of huge number of pools you may use this method:

     

     

    class mylist {

     

    "/this pool1"

     

    "/that pool2"

     

    }

     

     

    when HTTP_REQUEST {

     

    set lookup [HTTP::path]

     

    set myPool [findclass $lookup $::mylist " "]

     

    if {$myPool != ""}{

     

    pool $myPool

     

    }

     

    }

     

     

    You have the syntax here: Click here

     

     

    Be careful if you have uri starting with the same directory that should load balance different pools. With findclass it will stop at the first line in your class that match the request

     

     

    if that's the case you may have a look here: Click here
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Mar 18, 2008
    nmenant beat me to it.

    Here is the same method using Ravi's parameters

    
class dg_poolchoice {
"/abc poola"
"/xyz poola"
"/prq poolb"
"/def poolb"
}
when HTTP_REQUEST {
set choosenpool [findclass [string tolower [HTTP::uri]] $::dg_poolchoice " "]
if { $choosenpool != "" } { pool $choosenpool }
}

    /CB

  • Ravi_Rajan_7549's avatar
    Ravi_Rajan_7549
    Icon for Nimbostratus rankNimbostratus
    Mar 18, 2008
    Thanks a lot, earlier one worked fine. I will try this one too. This may be more cost effective in terms of CPU cycles.

     

     

    Ravi
  • Nicolas_Menant's avatar
    Nicolas_Menant
    Icon for Employee rankEmployee
    Mar 18, 2008
    Hi,

     

     

    if you have a huge number of different pools to select it's better to use classes.

     

     

    Usually we recommend to use switch for a number of tests which is < 100 and classes when you have more than 100 entries.

     

     

    HTH