iRule for limiting concurrent sessions to VS

Mohanad I believe you could do the following but this hasn't been tested so proceed with caution before configuring this in production.

when CLIENT_ACCEPTED priority 500 {

    set tbl "connlimit:[IP::client_addr]"
    set key "[TCP::client_port]"

}

when HTTP_REQUEST priority 500 {

    if { [table keys -subtable ${tbl} -count] > 1000 } {
        if {[HTTP::uri] contains "/v1/healthCheck"} {
            HTTP::respond 404 content "Maximum concurrent sessions limit reached"
            event CLIENT_CLOSED disable
            drop
        } else {
            event CLIENT_CLOSED disable
            reject
        }
    } else {
        table set -subtable ${tbl} ${key} "ignored" 180
        set timer [after 60000 -periodic { table lookup -subtable ${tbl} ${key} }]
    }

}

when CLIENT_CLOSED priority 500 {
    after cancel ${timer}
    table delete -subtable ${tbl} ${key}
}

Do you have any particular reason you couldn't use the connection limit of the pool member or total pool members connections and then generate a response based on those pool members being in a "down" state when the connection limit is reached? It seems like this unnecessarily overcomplicates your configuration and makes it a bit more difficult to support in the future.