Irule help

I wouldn't close the HTTP session in the event

HTTP_RESPONSE_RELEASE

as the HTTP response is about to be released from the F5 to the client but I would use the

HTTP_RESPONSE

event.

If you need to ensure it is the last

HTTP_RESPONSE

event then you can add a priority of 900 e.g.

when HTTP_RESPONSE priority 900 {

I do not think you need to close the TCP session else you will not send a response to the client at all and the command

HTTP::close

should close the connection after sending the response with the inserted header Connection: Close.

when HTTP_RESPONSE {
    if {[HTTP::status] == 204}{
        log local0. "HTTP close" 
        HTTP::close 
    }
}

Finally HTTP is stateless so even if the browser closes the TCP connection down following the response header Connection: Close being received it will likely just open a new one if it has another request to send. So this is removing the use of Connection: keep-alive from the client.