LTM Maint. Page issue

Hi Chris,

I think one issue is that you're using local variables in HTTP_REQUEST when setting the maint_prefix string (set maint_prefix "/maintenancepage"), but referencing a global variable (if {$uri equals ${::maint_prefix}}...) in the rest of the rule. Try changing the global variables to locals and see if you get better results. The Codeshare example declares the maint_prefix and maint_len variables in the RULE_INIT event. So they're implicitly defined as globals, even though they don't use the double colon in the name: 'set ::global_var value'.

If you make that change and it still doesn't work, can you log the output of [lindex $::maint_index_html 0]? Do you get the correct HTML string? If not, can you post what you see? Can you run 'b class main_index_html list' and post the output?

There are some other fixes/optimizations you could make to the example. You could save a few steps by using string map to trim off the maint_prefix. So instead of:

 
 set maint_prefix "/maintenancepage"   
 set maint_len [string length $maint_prefix]   
 set uri [HTTP::uri]   
 ... 
 set uri [string range $uri $::maint_len end]   
 

to:

 
 set maint_prefix "/maintenancepage"   
 set uri [HTTP::uri]   
 ... 
 set uri [string map [list $maint_prefix ""] $uri] 
 

Also, the redirect location should be an absolute URL (https://www.example.com/redirect_location.html) not just the path (/redirect_location.html):

ftp://ftp.rfc-editor.org/in-notes/rfc2616.txt

14.30 Location

The Location response-header field is used to redirect the recipient

to a location other than the Request-URI for completion of the

request or identification of a new resource. For 201 (Created)

responses, the Location is that of the new resource which was created

by the request. For 3xx responses, the location SHOULD indicate the

server's preferred URI for automatic redirection to the resource. The

 

field value consists of a single absolute URI.

Location = "Location" ":" absoluteURI

An example is:

Location: http://www.w3.org/pub/WWW/People.html

Aaron

Hi Aaron! Thanks again for the reply. You've always been extremely helpful.

 

 

I think I see a bit more with what is going on.

 

 

In the log output, I'm seeing:

 

 

can't read "maint_index_html": no such variable

 

 

I have it defined as class on the LTM, as a string and the file it is looking for is in /var/class. I have opened up the permissions just to make sure but no luck. I'm still not sure that I have made all of the variables global. Also, Where is the $::maint_index_html variable set, or becuase it is defined with the $:: it knows its a class?

What is your class name that contains the HTML? Is it named exactly maint_index_html? If so you can reference it using $::maint_index_html. Can you try this rule and see if it works for you?

    
  when HTTP_REQUEST {  
    
      Test the maint_index_html class  
     if {[info exists ::maint_index_html]}{  
        log local0. "\[lindex \$::maint_index_html 0\]: [lindex $::maint_index_html 0]"  
     } else {  
        log local0. "\$::maint_index_html doesn't exist!"  
     }  
    
       
      Service requests for files (URIs) from the maintenance page  
      Note that we always service these pages, even if the http_pool is up  
       
     set maint_prefix "/maintenancepage"  
     set maint_len [string length $maint_prefix]  
     set uri [HTTP::uri]  
     log local0. "redirect: [HTTP::uri]"  
     if { $uri equals $maint_prefix } {  
    
        HTTP::respond 301 "Location" "$maint_prefix/"  
    
     } elseif { $uri starts_with "$maint_prefix/" } {  
    
         Return the requested page  
        switch $uri {  
           "$maint_prefix/"             -  
           "$maint_prefix/index.html"   {  
              HTTP::respond 200 content [lindex $::maint_index_html 0] "Content-Type" "text/html"   
           }  
           "$maint_prefix/logo.png" {  
              HTTP::respond 200 content [b64decode [lindex $::maint_logo_png 0]] "Content-Type" "image/png"  
           }  
           default {  
              HTTP::respond 404  
           }  
        }  
        return  
     }  
       
      If the all members in the default pool are down, redirect to the maintenance page  
       
     if { [active_members [LB::server pool]] < 1 } {  
        HTTP::redirect "$maint_prefix/index.html"  
     }  
  }  
    

If not, can you check the /var/log/ltm file for any errors or debug?

Thanks,

Aaron

Well! Closer...I added your updated code and now get the following in the LTM log:

 

 

TCL error: (rule name) - can't read "maint_prefix": no such variable while executing "string length $maint_prefix"

Here is a tested version which uses local variables. I changed the class names to end with _class so it's a bit more clear that they're not standard global variables. I also changed the logic so that only one test would be done if the request isn't for a maintenance page. This should make the rule slightly more efficient for the majority of requests.

Can you update your class names to match these and give the rule below a try?

Thanks,

Aaron

Class containing the HTML:

   
   class maint_index_html_class {   
     type string   
     filename "/var/class/maint.index.html.class"   
   }   
   

Class containing the base64 encoded image:

   
   class maint_index_logo_class {   
     type string   
     filename "/var/class/maint.logo.png.class"   
   }   
   

iRule which references the HTML and logo class:

   
   when HTTP_REQUEST {   
      
         
       Service requests for files (URIs) from the maintenance page   
       Note that we always service these pages, even if the http_pool is up   
         
      set maint_prefix "/maintenancepage"   
      
      log local0. "New request to: [HTTP::uri]"   
      
      if { [HTTP::uri] starts_with "$maint_prefix" } {   
      
          Strip off the $maint_prefix from the URI as you can't easily do variable expansion    
          within a switch statement.   
          Note that requests for the exact maintenance URI will be set to a null string,   
          so handle null in the first switch case.   
         set uri [string map [list $maint_prefix ""] [HTTP::uri]]   
      
          Return the requested page   
         switch -- $uri {   
            "" {   
               log local0. "Request for $maint_prefix. Redirecting to $maint_prefix/"   
               HTTP::redirect "$maint_prefix/index.html"   
            }   
            "/" -   
            "/index.html" {   
               log local0. "Request for index. Responding with content: [lindex $::maint_index_html_class 0]"   
               HTTP::respond 200 content [lindex $::maint_index_html_class 0] "Content-Type" "text/html"    
            }   
            "/logo.png" {   
               log local0. "Request for logo.png. Responding with binary content"   
               HTTP::respond 200 content [b64decode [lindex $::maint_logo_png_class 0]] "Content-Type" "image/png"   
            }   
            default {   
               log local0. "Unrecognized request to URI: [HTTP::uri]"   
               HTTP::respond 404 content "Unrecognized request to [HTTP::uri]" "Content-Type" "text/html"    
            }   
         }   
         return   
      }   
         
       If the all members in the default pool are down, redirect to the maintenance page   
         
      if { [active_members [LB::server pool]] < 1 } {   
         HTTP::redirect "$maint_prefix/index.html"   
      }   
   }   
   

Interesting!!

 

 

Why is it retuning the class file name to the browser instead of the contents of it!!

 

 

LTM logs shows:

 

 

Dec 5 08:54:11 tmm tmm[1709]: Rule fieldnet_oos : New request to: /maintenancepage/index.html

 

Dec 5 08:54:11 tmm tmm[1709]: Rule fieldnet_oos : Request for index. Responding with content: /var/class/maint.index.html.class

 

 

 

Browser "view source" contents:

 

 

/var/class/maint.index.html.class

 

 

 

What am I missing!?! Is there a version issue or something here?

 

 

Thanks again!!

 

 

I'd guess that your class isn't defined correctly or the external file actually contains /var/class/maint.index.html.class. If you list the class definition you should see something like this:

 
  b class maint_index_html_class list all 
  
 class maint_index_html_class { 
    type string 
    filename "/var/class/maint.index.html.class" 
    mode rw 
    partition Common 
    "Maintenance pageSorry! This site is down for maintenance." 
    none 
    none 
 } 
 

Can you post what you see?

Thanks,

Aaron

Hi All,

 

Any body can help me to create the i-rules via GUI, I have tried to create it by my self, but looks like the maintenance page is not working.

 

Thanks

 

Have you checked out Kirk's sorry page generator? Does all the work for you:

 

 

http://devcentral.f5.com/weblogs/jason/archive/2009/05/12/host-that-sorry-page-on-your-big-ip.aspx Click Here

Hi Nit,

 

 

Which LTM version are you running? What have you configured and what is not working?

 

 

Aaron