expiresByType caching

Here's an old detailed example of what it appears you are trying to accomplish. I've swapped out the findclass command (deprecated in v10+) with the class command:

when HTTP_REQUEST { 
  if {[HTTP::method] eq "GET" and [HTTP::uri] eq "/"}{ 
    set expire_content_timeout 300 
  } else {
      set extention [string tolower [string range [HTTP::path] [string last . [HTTP::path]] end]]
      set expire_content_timeout [class match -value $extention equals cache_timers_by_filetype] 
  } 
} 

when HTTP_RESPONSE { 
  if { $expire_content_timeout ne "" } { 
    HTTP::header replace "Cache-Control" "max-age=$expire_content_timeout, public" 
    HTTP::header replace "Expires" "[clock format [expr ([clock seconds]+$expire_content_timeout)] -format "%a, %d %h %Y %T GMT" -gmt true]" 
  } else {    
      HTTP::header replace Expires {-1}     
  } 
}

The data-group format from that old example has changed as well:

ltm data-group internal cache_timers_by_filetype {
    records {
        .bmp {
            data 86400
        }
        .css {
            data 3600
        }
        .gif {
            data 86400
        }
        .htm {
            data 300
        }
        .html {
            data 300
        }
        .ico {
            data 604800
        }
        .jpeg {
            data 86400
        }
        .jpg {
            data 86400
        }
        .js {
            data 3600
        }
        .pdf {
            data 604800
        }
        .png {
            data 86400
        }
        .swf {
            data 604800
        }
    }
    type string
}