How do i append to a url

There are many ways of achieving it. The optimal solution will vary, depending on how many URLs (actually HTTP paths) you need to exclude from the HTTP to HTTPS redirection.

• If there's 1-3 exclusions, I would use IF/ELSEIF conditional statements
• If there are more than 3 exclusions, I would use SWITCH conditional statement
• If there are more than 25 exclusions, I would use IF conditional statement to compare against a list of entries in a data-group.

I'm aware of one exclusion, and I would use the following solution

when HTTP_REQUEST {

  if { ([string tolower [HTTP::host]] eq "www.xxx.yyy.zzz") && not([string tolower [HTTP::path]] eq "/activity") }{
    HTTP::respond 301 Location "https://www.xxx.yyy.zzz/directory/file" Connection Close
  }

}