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Kevin_Stewart
F5 Employee
F5 Employee

Problem this snippet solves:

Host and Return images directly from LTM. First example is for favicon.ico, but could be more/different/etc.

  1. Save your image(s) in a file-based class (can be an internal class, but it makes the config file messy). The following script actually let’s you save multiple images in a file class. Copy them all to a directory (/var/images) and run the script. It will create base64 encoded versions of each image in the /var/class/images.class. NOTE: Must run "b load" anytime an external file-based class is created or updated!
  2. Define the class as a Data Group List in the GUI: Local Traffic -> iRules -> Data Group List -> Create...

    • Name: images_class
    • Type: (External File)
    • Path/Filename: /var/class/images.class
    • File Contents: String
    • Key/Value Pair Separator: :=
    • Access Mode: Read Only
  3. Now listen for and respond to favicon requests:

Code :

#!/bin/bash

## clear /var/class_build/images_build.class
echo -n "" > /var/class/images.class

## loop through real images and create base64 data for images_build.class
for i in $(ls /var/images); do
        echo "\"`echo \"$i\"|tr '[:upper:]' '[:lower:]'`\" := \"`base64 /var/images/$i|tr -d '\n'`\"," >> \
                /var/class/images.class
done

 
when HTTP_REQUEST { 
  if { [string tolower [HTTP::path]] equals "/favicon.ico" } {
    if { [class match [findstr [string tolower [HTTP::path]] "/" 1] equals images_class] } {
      HTTP::respond 200 content [b64decode  [class lookup [findstr [HTTP::path] "/" 1] images_class]] \
        "Content-Type" "image/x-icon" \
        "Last-Modified" "Sun, 29 Mar 1970 18:53:56 GMT"
    }
  }
}

# Note:The “Last-Modified” header is there to allow it to cache. 4. And finally, if you want to serve up multiple images, not just favicon: 

## is the request an image? Process images from the base64 encoded image class
when HTTP_REQUEST { 
  if { [string tolower [HTTP::path]] ends_with ".jpg" or [string tolower [HTTP::path]] ends_with ".png" or [string tolower [HTTP::path]] ends_with ".gif" } {
    ## assume image name is after the last forward slash character in the URI
    if { [class match [string range [HTTP::uri] [expr [string last "/" [HTTP::uri]] + 1] end] equals images_class] } {
      HTTP::respond 200 content [b64decode [class lookup [string range [HTTP::uri] [expr [string last "/" [HTTP::uri]] + 1] end] images_class]] \
        "Content-Type" "image/png" \
        "Last-Modified" "Sun, 29 Mar 1970 18:53:56 GMT"
    }
  }
}
Version history
Last update:
‎18-Mar-2015 12:40
Updated by:
Contributors