Name Based Virtual Hosting irule efficiency

From my experience (as we do something similar in my organization), we've used data groups to handle all this (and parse the values to get information we need).

Regarding how to interact with data groups, this wiki page gives links to the class, findclass and matchclass functions, which should help guide you in the right direction.

For us, we sometimes use a format like

name1:value1|name2:value2|...

• DG Record Name:

  example.com

• DG Record Value:

  pool:my_pool|host:www.mynewhost.com

So in our iRule, we would check for

example.com

set host [string tolower [HTTP::uri]]
if { [class match $host equals DATA_GROUP_NAME] } {
    set param [class match -value $host equals DATA_GROUP_NAME]
     Add some checking for data integrity if necesary

    set params [split $param "|"]
    set pool [getfield [lsearch -inline -glob $params "pool:*"] ":" 2]
    set host [getfield [lsearch -inline -glob $params "host:*"] ":" 2]

     Set the pool
    pool $pool
     Change the host
    HTTP::host $host
}

It's a simple example, and depending on the amount of traffic, may not be the most efficient way of doing it, but I've found it's the simplest, as we just add a record to the data group and don't have to touch the iRule.

Hope this helps.