iRule for HSL or logging etc

If this is for HTTP, I recommend using a Request Logging Profile:

• Using the Request Logging Profile

If that is not suitable, however:

when LB_SELECTED {
    set hsl [HSL::open -publisher your_publisher]
    
    HSL::send $hsl "[clock format [clock seconds]] [IP::client_addr] [LB::server name] [clientside {IP::local_addr}]:[clientside {TCP::local_port}]"
}

If you wish to do this for HTTP, it's prudent to do this instead (if you want to log on each HTTP Request message):

when CLIENT_ACCEPTED {
    set hsl [HSL::open -publisher your_publisher]
}

when HTTP_REQUEST {
    HSL::send $hsl "[clock format [clock seconds]] [IP::client_addr] [LB::server name] [clientside {IP::local_addr}]:[clientside {TCP::local_port}]"
}