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GavinW_29074's avatar
GavinW_29074
Icon for Nimbostratus rankNimbostratus
Dec 08, 2011

Extract value from VirtualName

Hi there,

I'm trying to write an iRule condition that needs to know part of the [Virtual Name] value...

A couple of examples are:

/Common/Test.App/app.test.com_https

/Common/app2.test.com_http

I want to get the bit between the last '/' and the '_'...

I've tried using the scan command as follows:

 scan $virtualname {%*[^/]/%[^_]} vname
           log local0. "\$vname = $vname"

However I keep getting:

can't read "vname": no such variable while executing "log local0. "\$vname = $vname""

Any ideas???

Or is there a better way of doing it?

Cheers

Gav

application delivery
dev
devops
iRules
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Dec 08, 2011
    Hi Gavin,

    Your scan pattern of %*[^/]/%[^_] would not work because all virtual server names in 11.x will start with a /. I don't think you can use scan alone to match a variable number of subfolders.

    Also, with scan, you can check the number of matches before trying to use one of the match variables: 

    
if {[scan $virtualname {%*[^/]/%[^_]} vname] == 1}{
   log local0. "Matched $vname from $virtualname"
} else {
   log local0. "Couldn't parse $virtualname"
}

    Here are three ways to do it. The string commands are more complicated but also more efficient than the single regexp. I'd guess the second option is most efficient, but you could use timing to test this:

    http://devcentral.f5.com/wiki/iRules.timing.ashx

    scan [string range [virtual name] [expr {[string last / [virtual name]] +1}] end] {%[^_]%*s} vs_name

    log "scan: $vs_name"

    set vs_name [findstr [string range [virtual name] [string last / [virtual name]] end] "/" 1 "_"]

    log "findstr: $vs_name"

    regexp {(/.*/)?[^_]+} [virtual name] unused unused vs_name

    log "regexp: $vs_name"

    Aaron
  • GavinW_29074's avatar
    GavinW_29074
    Icon for Nimbostratus rankNimbostratus
    Dec 12, 2011
    Aaron

     

     

    Cheers for the response.

     

     

    I've set-up the second option, and it works exactly as I need it to...

     

     

    Haven't done any timings on them yet, but will keep an eye on it...

     

     

    Cheers

     

    Gavin