...
A speech remained pending. I'm talking about the ConfigMap manage-security-groups key. If set to true, a new group would appear in the Project/Network/SecurityGroups tab, containing the NodePorts of the implemented services (in this case the ports 31156 and 30458 of the coffee and tea services). In this way, the group can be associated with cluster instances. Why did I recommend setting the value to false? Because it would be useless, since the ports are already open. In fact, when installing Kubeadm (see "Preliminary stepsteps" in cap. 2), it is recommended to open the range of ports 30000-32767 for WorkerNodes, which corresponds to the range in which a NodePort can be generated.