Using iruel for redirects

Please, by all means, continue singing, and let's all think happy thoughts about the "findclass" command...

 

:D

 

 

I have some new findclass URI mapping tricks up my sleeve that I haven't yet made pretty enough to post on the CodeShare, and this may be just the kick I need to make that happen.

 

 

If you can please provide some specific examples of the URI's for which you need to perform redirects, I'm sure we can get you going.

 

 

The critical details are going to be the "inconsistencies" or variations re: parts of the URI that must be evaluated to choose the correct redirect target, for example::

 

 

redirect /dir2/thisfileonly to X

 

redirect /dir1/dir2/* to Y

 

redirect /dir1/ to Z

 

 

more later

 

/deb

 

This is the current rule that i am testing,

 

 

when HTTP_REQUEST {

 

if { [HTTP::uri] eq "/histology" and [HTTP::host] == "www.thermo.com" } {

 

HTTP::redirect http://www.thermo.com/com/cda/category/category_lp/0,2152,53,00.html

 

} else {

 

use pool www.thermo.com-pool_80

 

}

 

}

 

 

so basically, I will have 600 'if's' all with a different uri string to match and redirect to a specific page.

 

 

if { [HTTP::uri] eq "/histology" and [HTTP::host] == "www.thermo.com" } {

 

HTTP::redirect http://www.thermo.com/com/cda/category/category_lp/0,2152,53,00.html

 

 

Well, I'm sort of trying to edge you away from the "death by 600 if's" version of the iRule you could create... but to do so, we'll need to know if the decision will always be based on the hostname and first directory, as in the example you give above, or will there be some variation in what needs to be evaluated -- different hostnames, different of directories, etc.

 

 

/deb

 

always based on hostname and 1st directory.

Sure, then, that's pretty straightforward:

Create a class list containing your request and redirect details in 2 columns, separated by a space -- hostname/firstdir in one, then the redirect target in the other.

class myRedirects {
  "www.thermo.com/histology http://www.thermo.com/.../0,2152,53,00.html"
  "www.whatever.com/dir1 http://newhost/newuri"
}

Then create this iRule an apply to the virtual server:

rule URIredirects {
  when HTTP_REQUEST {
    set req "[HTTP::host]/[getfield [HTTP::uri] "/" 2]"
    set redir [findclass $req $::myRedirects]
    if {$redir !=""}{
      HTTP::redirect $redir
    }
  }
}

/deb

Thats pretty sweet. Is the class list stored in memory, do i need to worry about memory consumption

stupid question, hpw do i create the class list. I read some doc, looks like i need the webacclerator module, which i do not have

oh, sorry, they are still called classes in the config, but I keep forgetting they are now called "Data Group Lists" in the GUI and doc.

 

 

You can just browse in the GUI to Local Traffic/iRules, click on the Data Group List tab, and create a new list of type "String". Add your list, one row at a time, with a space separating the host/uri and the redirect (GUI will add the double quotes for you).

 

 

Class lists are stored in the bigip.conf file, and are loaded into memory with the rest of the config. We have customers using very large class lists with simple iRules such as this with minimal performance impact.

 

 

/deb

thanks. is there a trick to adding the 600 or so strings, besides hand editing the conf file..?

You can edit the config file, in which case you'd need to just follow this format:

class myRedirects  {
   "hydration.company.com http://www2.co.com/hydration.html"
   "nhra.com http://www.us.company.com/nhraHome.do"
   "redirect.co.com http://www.company.com/"
   "thecompany.com http://www.thecompany.com/"
}

Once the conf file is saved, load into memory with a manual config reload ("bigpipe load" at the command line). Once the class is created, indivudual members can be updated on the fly in the GUI.

If you won't need to be updating it on the fly from the GUI, you can create what's called an "external class" which uses a separate text file to store the data. To do so, create a new text file in the /config filesystem (to sync automatically) in the following format:

"hydration.company.com http://www2.co.com/hydration.html",
"home.company.com http://www.us.company.com/Home.do",
"redirect.co.com http://www.company.com/",
"thecompany.com http://www.thecompany.com/",

and create a class of type "External" referencing this file. Note the trailing comma on each line, including the last. Changes to the file require a manual config reload before they take effect ("bigpipe load" at the command line).