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Terrence's avatar
Terrence
Icon for Nimbostratus rankNimbostratus
Jul 09, 2009

Writing a generic Irule

A while back I took the LTMMaintenancePage to serve up a maintenance page for the web application. We are about to load balance a second application and would also like to use the maintenance page. Although not fully tested I was able to substitute the Description with the hostname with the following code.

 

set site_name [HTTP::host]

 

set index_html [string map "SITE $site_name" ${::template}]

 

 

This isn't ideal as something HTTP:host is not the "name" of the application. What I would like to do is have a variable persist upon virtual server similar to the STATS profiles, however I want a string which I could then substitute into the template.

 

 

 

 

also I currently have three lines

 

set site_name [HTTP::host]

 

set index_html [string map "SITE $site_name" ${::template}]

 

HTTP::respond 200 content $index_html "Content-Type" "text/html"

 

 

Can anyone show me the proper brackets to put it all in a one liner?

 

HTTP::respond 200 content [string map "SITE [HTTP::host]" ${::template}] "Content-Type" "text/html"

 

 

 

I unfortunately do not have a test box to test on(its currently in paperwork somewhere), but we have a maintenance window this weekend which I can have some time to do some testing.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References:

 

http://devcentral.f5.com/wiki/default.aspx/iRules/LTMMaintenancePage.html
application delivery
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iRules

2 Replies

  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Jul 09, 2009
    What you've got should be equivalent:

     

     

    set site_name [HTTP::host]

     

    set index_html [string map "SITE $site_name" ${::template}]

     

    HTTP::respond 200 content $index_html "Content-Type" "text/html"

     

     

    HTTP::respond 200 content [string map "SITE [HTTP::host]" ${::template}] "Content-Type" "text/html"

     

     

    You could remove the curly braces in $::template, but they don't hurt anything by being there.

     

     

    Is that what you were looking for? I'm not sure what you meant by "This isn't ideal as something HTTP:host is not the name of the application.".

     

     

    Aaron

     

  • Terrence's avatar
    Terrence
    Icon for Nimbostratus rankNimbostratus
    Jul 10, 2009
    What I wanted is a way to have a variable available to all servers applied to a particular VIP, with a scope of that VIP. I started throwing together a code where I can use a generic maintenance page irule, although it is not how I orginally set out to accomplish it.

     

         
 class maint_home_css {     
     type string     
     filename "/var/class/maint.home.css.class"     
 }  
     
 class maint_index_html {     
     type string     
     filename "/var/class/maint.index.html.class"     
 }   
    
 class maint_logo_gif {     
    type string     
    filename "/var/class/maint.logo.gif.class"     
 }     
  
 class maint_site_desc {     
       "lists.aa.net" := "Company's Support Mailing lists"     
       "cct.aa.net"       := "CAS - Central Authentication(Dev)"     
       "login.aa.net"     := "Central Authentication Service(CAS)"     
       "forums.aa.net"      := "Company's Support Forums"     
 }     
  
 rule webserver {     
   when HTTP_REQUEST {     
        If the http_pool is down, redirect to the maintenance page     
            
       if { [active_members webct-pool] < 1 } {     
          switch [HTTP::uri] {     
                 "/"        -     
                 "/index.html" {     
                        set index_html [b64decode [string map "SITE [class lookup [HTTP::host] maint_site_desc]" [class element 0 maint_index_html]]]     
                        HTTP::respond 200 content $index_html "Content-Type" "text/html"     
                 }     
                 "/logo.gif"   { HTTP::respond 200 content [b64decode [lindex $::maint_logo_gif 0]] "Content-Type" "image/gif" }     
                 "/home.css"   { HTTP::respond 200 content [lindex $::maint_home_css 0]           "Content-Type" "text/css" }     
                 "default" { HTTP::respond 301 "Location" "/"  }     
          }     
          return     
       }     
    }     
 }