Retrieving info from server

The best solution for your question is to implement this as an iControl solution. You can use the calling executable to request the aggregate number of connections from the backend servers and then disable the virtual from an iControl call.

 

 

If you want to do this with an iRule it is tricky but theoretically could be done with something like this

 

 

1. Every "n" requests, change the URI in the HTTP_REQUEST event to point to a "health" service that will return the metrics you want to work on in either headers or payload.

 

2. On the HTTP_RESPONSE, if the request was from the health service, then check the returned metrics.

 

3. If metrics say to stop connections, issue a "reject" command.

 

4. If metrics give a green light to continue, change the HTTP::uri back to the original value and issue a HTTP::retry. This will retry the HTTP request to the pool of servers. Keep in mind that you'll have to buffer the entire HTTP::request (headers) and the HTTP::payload and include both of them in the call to HTTP::retry.

 

 

Theoretically this could work but it has not been tested.

 

 

Hope this helps...

 

 

-Joe

Thanks for the reply!

 

In my scenario, because the info on the number of outbound concurrent connection is not on Big-IP, retreiving the info from Big-IP would be difficult. IMHO, workaround would be that one of servers retrieve the info from all the members and then, if the it exceeds the limit, issue a call to disable VS.

 

The suggestion to retrive the value from response for request to specific URI looks good, I shall try.

 

 

regards,

I am trying to create a rule like below to test the logic suggested, but it looks like it is failing...

 

 

when HTTP_REQUEST {

 

changeing URI.

 

HTTP::uri "/check_conn"

 

}

 

when HTTP_RESPONSE_DATA {

 

checking number of connections.

 

if { [findstr [HTTP::payload] "Concurrent=" 11 14] matches "100"

 

}

 

reject

 

return

 

}

 

 

Does anyone know how to get this work more gracefully or have some samples so I can customize it in my environment??

 

 

regards,

 

The HTTP_RESPONSE_DATA event won't be fired unless you call [TCP::collect inside the HTTP_RESPONSE event.

 

 

You'll also want to be sure to do a TCP::release after you're done precessing the payload.

 

 

Colin