Single Node Kubernetes on CoreOS - Complete Setup Guide#

Setting up a lightweight, single-node Kubernetes environment is perfect for development, testing, and learning purposes. This guide walks you through deploying Kubernetes on Fedora CoreOS - a minimal, container-focused operating system designed for running containerized workloads.

We’ll break this process into two main stages:

Setting up the CoreOS virtual machine
Installing and configuring Kubernetes

Prerequisites#

Before starting, ensure you have the following on your host system:

Fedora CoreOS qcow2 image (download here)
podman installed (dnf install podman)
libvirt and virt-install tools (dnf install libvirt virt-install)
A generated SSH key pair (ssh-keygen -t ed25519)

Stage 1: Basic CoreOS Setup#

1. Create Basic Ignition Config#

Ignition is the CoreOS configuration system. Create a file named basic.bu:

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variant: fcos
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version: 1.4.0
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passwd:
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  users:
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    - name: core
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      ssh_authorized_keys:
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        - YOUR_SSH_PUBLIC_KEY_HERE
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storage:
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  files:
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    - path: /etc/hostname
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      mode: 0644
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      contents:
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        inline: |
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          k8s-node

Replace YOUR_SSH_PUBLIC_KEY_HERE with the content of your ~/.ssh/id_ed25519.pub file.

2. Generate Ignition File#

Convert the Butane configuration to an Ignition file:

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podman run --interactive --rm \
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  quay.io/coreos/butane:release \
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  --pretty --strict < basic.bu > basic.ign

3. Create VM Script#

Create a script named start-node.sh to launch your CoreOS VM:

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#!/bin/sh
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IGN_CONFIG=/path/to/basic.ign
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IMAGE=/path/to/fedora-coreos.qcow2
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VM_NAME=k8s-node
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VCPUS=2
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RAM_MB=4096
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DISK_GB=20
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STREAM=stable
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chcon --verbose --type svirt_home_t ${IGN_CONFIG}
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virt-install --connect="qemu:///system" \
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    --name="${VM_NAME}" \
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    --vcpus="${VCPUS}" \
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    --memory="${RAM_MB}" \
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    --os-variant="fedora-coreos-$STREAM" \
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    --import --graphics=none \
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    --disk="size=${DISK_GB},backing_store=${IMAGE}" \
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    --qemu-commandline="-fw_cfg name=opt/com.coreos/config,file=${IGN_CONFIG}"

Update the paths to your Ignition config file and CoreOS image.

4. Launch VM#

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chmod +x start-node.sh
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./start-node.sh

5. Note VM IP Address#

During boot, you’ll see network information. Look for a line showing the IP address assigned to the VM: