The monitoring section in fast-epdg.conf:

monitoring {
    enabled = yes
    listen_port = 9817
    listen_address = 0.0.0.0
    update_interval = 10
    metrics {
        ikev2 = yes
        gtp = yes
        diameter = yes
        service = yes
        session = yes
        app = yes
        system = yes
    }
}

Each group of metrics can be independently turned on/off without recompilation.