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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?
softshipper
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  • Are your VPS on the same network? Is not clear for me about the firewall rules, and where you are trying to apply them. Check [this link](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#check-required-ports) – Mr.KoopaKiller Jan 21 '20 at 12:48
  • VPS's are in the public network, everyone can ping them. But they are from the same provider. – softshipper Jan 21 '20 at 13:04

4 Answers4

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  • How to prepare servers, that they can talk to each other

For prepare your Ubuntu instances to install Kubernetes you could check this guide. Use the kubespray documentation to create your cluster.

  • 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.

You could use iptables to make specific rule from you nodes, but I think it will be a challenge to manage theses rules for your service by hand... you could try but it will be really hard to manage and maintain.

What else do I have to consider?

I recommend this setup for understand how to Kubernetes works and for tests purposes, but it is not production-ready, the security of your node could be compromised since you are exposed the Kubernetes ports over the internet.

You can consider also use kubernetes as a single node, take a look is this link.

Mr.KoopaKiller
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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.

JulioHM
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  • `there are flaws during the cluster lifecycle` what exactly do you mean? – softshipper Jan 21 '20 at 15:54
  • Not every step on replacing nodes is 100% documented. https://github.com/kubernetes-sigs/kubespray/issues/3471#issuecomment-530036084 – JulioHM Jan 22 '20 at 20:12
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    Also you might run into issues migrating Kubernetes versions depending on payload (e.g. upgrade-cluster.yml drains nodes. If you have stuff with pod disruption budgets kubespray can't know that) – Flowkap Feb 12 '20 at 15:08
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Here what i fill which you can do -

  1. How to prepare servers ? - I used the the vagrant to spin up the servers
  2. How to setup the firewall? - Either you can set up the firewall rules for the IPs which you have defined in the vagrant file or disable the firewall between the nodes.

I would recommend going through the following guide which covers all the steps which i used for setting up kubernetes cluster using kubespray -

https://jhooq.com/kubespray-12-steps-for-installing-a-production-ready-kubernetes-cluster/

Rahul Wagh
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Also consider things Ubuntu does you might not want, such as checking swap (even when you don't have any) and disabling unattended upgrades which can bring down an otherwise capable system:

sudo swapoff -a && \
apt remove unattended-upgrades -y && \
killall -9 unattended-upgr 2>/dev/null
vhs
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