Respond with 5xx message when pool members connection limits reached (iRule?)

Changed the iRule to be v11-compliant

when RULE_INIT {
        Set a global max for number of concurrent TCP connections
    set static::max_connections 2
     Set an HTML response to sent to clients who make a request while the VIP is over the max      connection count
    set static::html_content "over limit"

     Print debug messages to /var/log/ltm?  1=yes, 0=no
    set static::debug 1

     Initialize a counter for active connections (don't modify this)
    set static::active_connections 0
    }
    when HTTP_REQUEST {

     If we're over the limit for this connection, send a response
    if {$static::active_connections > $static::max_connections}{

     Send a response
    HTTP::respond 200 content $static::html_content

     Close the connection
    TCP::close

     Log a message to /var/log/ltm if debug is enabled
    if {$static::debug}{log local0. "Over limit (current/max:               $static::active_connections/$static::max_connections). Sent response to [IP::client_addr]"}

     We're not over the limit, so check if this is the first HTTP request on the TCP connection.  
    } elseif {[HTTP::request_num] == 1}{
      set validrequest 1
       Increment the TCP connection count.
      incr static::active_connections 1
    }
 }

when CLIENT_CLOSED {
    A connection was closed, so decrement the global counter
   if {$validrequest == 1}{
       incr static::active_connections -1
   }
}