Tag: F5 Sorry Image

F5 iRule – Serving Sorry Image

There are 3 steps to creating the F5 iRule to serve the image of a sorry page. Serving image of sorry page is utilized when you need to serve non-English characters which may not be compatible with F5. Of course, you can use it even for simple sorry pages with English characters.

There are 3 main steps:

  • Create a base64 image of the original Sorry Page Image
  • Create a datagroup that references the base64 Sorry Page Image
  • Create an iRule that reference the datagroup and attach this to the Virtual Server that requires the Sorry Page iRule.

 

Create a base64 image of the original Sorry Page Image:

  1. Copy the image (SORRY_IMAGE.png – this should be less than 46KB in size) onto F5’s directory /var/tmp/SORRY_IMAGE.png
  2. The following command should be copied to the F5 shell as a single line in order to create the base64 image
    echo \"SORRYIMAGE\" \:\= \"`base64 /var/tmp/SORRY_IMAGE.png | xargs echo | sed 's/ //g'`\"\, > /var/class/SORRY.class
  3. Check /var/class/SORRY.class
    [root@f5-ltm:Active] config # head /var/class/SORRY.class
    "SORRYIMAGE" := "iVBORw0KGgoAAAANSUhEUgAABAAAAAMACAMAAACNZOU/A ...... <<remaining output omitted>>

 

Create a datagroup that references the base64 Sorry Page Image via GUI:

Name: SORRY_PAGE
Partition: Common
Type: (External File)
Path / Filename: /var/class/SORRY.class
File Contents: String
Key/Value Pair Separator: :=
Access Mode: Read/Write

 

Create an iRule:

when HTTP_REQUEST {
  if { ([active_members [LB::server pool]] < 1)} {
      HTTP::respond 503 content [b64decode [class element -value 0 SORRY_PAGE]]
      event disable
     }
}

iRule references the datagroup SORRYPAGE which references the file /var/class/SORRY.class and this contains the base64 image of the sorry page. SORRY_IMAGE.png which is utilized to create the base64 image should not be more than 46KB. This is a limitation on the F5 LTM.