Fetching substring from a string in kibana

[Rios]

It's common way to use as tsullivan suggested and will work.

Also, it's not forbidden to use parsers:

   dissect { 
     mapping => {  "url" => "/%{urldiss}/%{}" }
   }
 
   grok { match => { "message" => [ "^\/%{DATA:urlgrok}\/"] } }