Prepare VPS for installing Kubernetes with Kubespray

I have 3 VPS based on Ubuntu 18.04 server and would like to build a kubernetes cluster.

I going to use Kubespray to install the Kubernetes cluster and my questions are:

• How to prepare servers, that they can talk to each other
• How to setup the firewall, that the communication between VPS do not block
• Is it possible to configure the firewall, to open particular port for a particular IP address. For example, only a VPS with 1.11.111.110 is allowed to access the port 10255 on VPS 1.11.111.111.
• What else do I have to consider?

If you are using Kubespray, I strongly recommend just following their guidelines and documentation. They are very comprehensive and detailed.

https://kubespray.io/#/

In its current version, Kubespray is a comprehensive wrapper for kubeadm, adding a number of features missing from kubeadm itself.

In short, preparing hosts is a matter of allowing remote SSH from the control machine (which is usually your own desktop), prepare the inventory carefully reviewing all of its *.yaml files. Once you configure the inventory and install a few python dependencies on the VPS hosts, just fire Kubespray from the terminal and wait.

Keep in mind that it's not a perfect tool, and there are flaws during the cluster lifecycle. But it will at least give you a headstart bootstrapping a full production ready cluster.