HTTP response timeout

I don't think it's really possible to do exactly what you've described with an iRule. I can't think of a way to start a counter and then check to see if it's passed the timeout x number of seconds later. The check would have to be done in an event.

 

 

The closest that I can think of is to set a timer when the HTTP request headers are parsed in HTTP_REQUEST. You could then check the elapsed time in the HTTP_RESPONSE event (when LTM parses the server's response HTTP headers). If the response was received in less than 1 second you could allow the response to be sent back to the client. If the response comes in after 1 second you could drop the response when it's received and send back a different response to the client.

 

 

Out of curiosity, why do you need to set such a low timeout? Most HTTP clients can handle a longer wait than one second.

 

 

Aaron

Hi Colin, thanks for your answer. About your curiosity, this is a requirement for a project (I don't know the reason ... :-). About your suggestion, can you send me an example ? Thanks in advance. Mario

Sorry, my reply is addressed to Aaron (Hoolio) ... BR Mario

Mario,

Here's a first attempt (untested):

 
 when HTTP_REQUEST { 
  
     Save the start time when HTTP request headers were parsed 
    set start_time [clock clicks -milliseconds] 
 } 
 when HTTP_RESPONSE { 
  
     Check if the response headers from the server were parsed in more than 1000ms 
    if {[expr {[clock clicks -milliseconds] - $start}] > 1000}{ 
  
        Respond back to client 
       HTTP::respond 200 content "Response time was too long" 
    } 
 } 
 

The default pool on the VIP will be used. If you want to add pool selection logic to the rule, you can do it in the HTTP_REQUEST event.

Aaron

Hi Aaron, thank you very much for your help. Kind regards, Mario

Hi,

 

I know there is also a command : "when HTTP_REQUEST timing on " but i don't know if this can be used for this scope.

 

BR,

The timing command allows you to monitor how many CPU cycles are used when processing a command or event. It's strictly for reporting purposes. You can get more detail on the command from the timing wiki page (Click here).

 

 

Aaron

Hello Aaron (Hoolio), I have tested your example and it works. However, it doesn't cover exactly what requested: in fact the HTTP response for timeout too long should be sent by BIGIP if a timer of 1 sec expires and the real server doesn't send the answer. In your example the irule is instead triggered when the BIGIP receives the answer by the server. I think we should use a timeout event but I can't find anything like this. Do you have any idea ? Thank you very much for your help. Mario

Hi Mario,

 

 

You're correct. The rule does exactly that. This is the best that can be done with current functionality. If, F5 provides a true timer mechanism at some point, you could update the rule to respond without depending on the server response to trigger your response.

 

 

Aaron