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Vincent_Power_9's avatar
Vincent_Power_9
Icon for Nimbostratus rankNimbostratus
Jul 03, 2007

Performance Question in Large iRule

I run into this situation a lot, where an iRule will look like this (our business users want everything behind one hostname/port).

Historically we've been building them like this since it is quick and easy to maintain.


 Pool One
if { [HTTP::uri] starts_with "/abc/" } {
  pool one
} else if { [HTTP::uri] starts_with "/bcd/" } {
  pool one
} else if { [HTTP::uri] starts_with "/cde/" } {
  pool one
} else if { [HTTP::uri] starts_with "/def/" } {
  pool one
} else if { [HTTP::uri] starts_with "/efg/" } {
  pool one
} else if { [HTTP::uri] starts_with "/hij/" } {
  pool one
} else if { [HTTP::uri] starts_with "/ijk/" } {
  pool one
} else if { [HTTP::uri] starts_with "/jkl/" } {
  pool one
}
 Pool Two
if { [HTTP::uri] starts_with "/klm/" } {
  pool two
} else if { [HTTP::uri] starts_with "/lmn/" } {
  pool two
} else if { [HTTP::uri] starts_with "/mno/" } {
  pool two
} else if { [HTTP::uri] starts_with "/nop/" } {
  pool two
}
 Pool Three
if { [HTTP::uri] starts_with "/opq/" } {
  pool three
} else if { [HTTP::uri] starts_with "/pqr/" } {
  pool three
} else if { [HTTP::uri] starts_with "/qrs/" } {
  pool three
} else if { [HTTP::uri] starts_with "/rst/" } {
  pool three
}

What would a better way be to make iRules like this more efficient? I don't think "switch -glob" meets my specific need.
application delivery
dev
devops
iRules

3 Replies

  • Deb_Allen_18's avatar
    Deb_Allen_18
    Historic F5 Account
    Jul 03, 2007
    Not sure why switch -glob wouldn't do the trick:
    
switch -glob [string tolower [HTTP::uri]]{ 
  /abc/* -
  /bcd/* -
  ...
  /jkl/* { pool one }
  /klm/* -
  /lmn/* -
  ...
  /nop/* { pool two }
  /opq/* -
  /pqr/* -
  ...
  /rst/* { pool three }
}

    Or if you're going to switch only on the first level directory, you could avoid -glob switch if you parse out just that value for comparison:
    
switch [getfield [string tolower [HTTP::uri]] / 2] { 
  abc -
  bcd -
  ...
  jkl { pool one }
  klm -
  lmn -
  ...
  nop { pool two }
  opq -
  pqr -
  ...
  rst { pool three }
}

    Or you could use a class listing the first directory and pool with a findclass (maintaining the list in the class instead of the iRule is probably easier administratively.)

    Class:
    class VirtualHosts {
  abc one
  bcd one
  ...
  rst three
}
    iRule snip:
    
set myPool [findclass [getfield [string tolower [HTTP::uri]] / 2] $::VirtualHosts " "]
if {$myPool != "" }{
  pool $myPool
}

    HTH

    /deb

  • Vincent_Power_9's avatar
    Vincent_Power_9
    Icon for Nimbostratus rankNimbostratus
    Jul 03, 2007
    Alright, I guess I didn't understand the switch command well enough.

     

     

    and getfield looks to be very useful

     

     

    Thanks,

     

    Vince