Ubuntu Prerequisites

This document describes Ubuntu specific pre-requisites for a BareOS PMK cluster. It is part of the overall Quick Setup Guide for PMK. If you haven’t already, we recommend starting with that guide first.

Operating System Install

To prepare a physical or virtual node to be part of a BareOS Kubernetes cluster:

  • Install the latest version of Ubuntu 16.04 (Support for Ubuntu 18.04 is coming soon!)
  • Update all packages to receive the latest security and bug fixes.

Disable Firewall Services (If Enabled)

If ufw or firewalld services are enabled, you need to disable them so that the node can communicate with other nodes in the cluster on various required ports. See Networking Prerequisites for more info on what ports are used by various Kubernetes services.

Install Required Dependencies and Update Ubuntu

For Ubuntu, run the following command to install required dependencies and update all installed packages.

 apt-get update \
 apt-get install curl uuid-runtime \
 apt-get upgrade

Disable any other incompatible networking services

Ensure that there is no other external / incompatible networking software running on the node as it can interfere with docker and Kubernetes networking services.

Disable Swap

Starting Kubernetes version 1.8, all Kubernetes master and worker nodes are expected to have swap disabled. This is the recommended deployment as mentioned in the Kubernetes changelog.

If swap is not disabled, kubelet service will not start on the masters and worker nodes.

Run the following command to disable swap immediately:

 sudo swapoff -a 

Run the following command to update fstab to persist disabling swap across reboots of the node.

sudo sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab

The above command comments out all swap entries in the /etc/fstab file.