URI HASH persistence based on URI depth and string length
Problem this snippet solves: When dealing with caching or AV analysis systems, we may need to define a static persistence method to maximize hits and performances on backend servers. How to use this snippet: Installation You just need to assign the irule to a standard Virtual Server. The VS require at least an http profile and ssl profiles (if doing ssl offloafing or ssl bridging) Variables static::lb_depth - define a subset of the path to use for HASH calculation static::lb_len - define the number of chars to retrieve in the path for HASH calculation static::timeout - define the timeout of the persistence record Features Universal persistence Persistence using URI Hash Specify a depth and/or a string length to get a subset of the URI for the Hash calculation Code : when RULE_INIT { # define the depth of the path that will be used for HASH calculation set static::lb_depth 5 # lb_len variable should be set to 0 if you don't want to use it set static::lb_len 0 set static::timeout 3600 } when HTTP_REQUEST { # initialize required variables set path [string tolower [HTTP::path]] set depth [URI::path [HTTP::uri] depth] # define the depth of the path for hash calculation if { $depth < $static::lb_depth } { set depth_path [HTTP::path] } else { set depth_path [URI::path [HTTP::uri] 1 $static::lb_depth] } set len [string length $depth_path] # define the chars length to be processed for hash calculation if { $static::lb_len > 0 and $static::lb_len < $len } { binary scan [sha1 [string range $depth_path 0 $static::lb_len-1]] w1 key } else { binary scan [sha1 $depth_path] w1 key } persist uie $key $static::timeout } Tested this on version: 11.3