Questions for calculate concurrent session

There isn't a way from an iRule to get a count of sessions stored in the session table. There is an existing CR (CR61210) requesting this functionality. You could open a case with F5 Support to ask them to build this feature in a future release.

 

 

That said, there is a work around for this.

 

 

You can add a session table entry by using the iRule session command:

 

 

Generate a new 8 digit client ID

 

set client_id "client_id_[format "%08d" [expr { int(100000000 * rand())}]]"

 

 

Insert a cookie with the client ID

 

HTTP::cookie insert name $::session_cookie_name value $client_id

 

 

Add the client ID to the session table with a session timeout (in seconds). The value of "1" isn't used for anything.

 

session add uie $client_id "1" $::session_timeout

 

 

The session timeout will be enforced by TMM so that old session table entries are removed after the timeout expires. Using a shell script, you can get a count of the session table entries from the command line by running 'bigpipe persist':

 

 

session_count=`b persist mode universal show all|grep -c client_id`

 

 

You can then update a datagroup with the current count using the 'bigpipe class' command:

 

 

b class current_sessions_count_class $session_count

 

 

You can then reference the current_sessions_count_class from your iRule:

 

 

set ::available_sessions [expr $::max_session_count_class - $::current_sessions_count_class]