Oracle Cloud Free ARM Kubernetes Cluster

This is a guide to install a single-node Kubernetes cluster on a free Oracle Cloud ARM server.

Account

Create an Oracle Cloud account from here: https://cloud.oracle.com/

Server

Create a new compute instance https://cloud.oracle.com/compute/instances/create

Name: oracle-k8s (any valid name is fine)

Create in compartment: your-username (root)

Placement: leave everything as default.

Security: leave everything as default.

Image and shape:

• Canonical Ubuntu 22.04
• VM.Standard.A1.Flex with 4 OCPUS and 24 GB of RAM

Networking:

• Primary network: Create new virtual cloud network
  • New virtual cloud network name: vcn-k8s
  • Create in compartment: your-username (root)
• Subnet: Create a new public subnet
  • New subnet name: subnet-k8s
  • Create in compartment: your-username (root)
  • CIDR block: 10.0.0.0/24
• Public IPv4 address: Assign a public IPv4 address

Add SSH keys:

• Generate a key pair for me
  • Save private key

Boot volume:

• Specify a custom boot volume size: yes
  • Boot volume size: 200 GB (you may use 100 GB and leave 100 GB for the free x86_64 servers)
  • Boot volume performance: 10 VPU
• Use in-transit encryption: yes
• Encrypt this volume with a key that you manage: no

Oracle might give you an estimate cost for the boot volume which you can disregard, the free tier includes 200 GB of block volume storage.

Live migration: active

Click “Create” to create the machine.

Connecting

At the end of previous step, you should have been redirected to the instance page, which you can open by clicking on your instance’s name from the instances page: https://cloud.oracle.com/compute/instances/

You can use PuTTY to open a SSH conection to your server.

Use the “Public IP address” to connect, and log-in as the “Username”.

SSH port 22 is already exposed.

Installing Kubernetes

The first requirement to install Kubernetes is Docker: https://docs.docker.com/engine/install/ubuntu/

sudo install --mode=0755 --directory /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

echo \
  "deb [arch="$(dpkg --print-architecture)" signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu \
  "$(. /etc/os-release && echo "$VERSION_CODENAME")" stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

sudo apt update
sudo apt install --yes docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

To validate Docker’s installation, run this command and ensure there are no errors:

sudo docker run hello-world

The second requirement is cri-dockerd: https://github.com/Mirantis/cri-dockerd/releases

Unfortunately this tool doesn’t come with pre-built packages for ARM, so it will have to be built from source.

# Install build tools (marking as "auto" will make the installation temporary)
sudo apt install --yes make golang-go
sudo apt-mark auto make golang-go

# Clone Git repository
cd ~
git clone https://github.com/Mirantis/cri-dockerd.git
cd cri-dockerd

# Build (this will take a while and won't report any progress)
make cri-dockerd

# Install
sudo mkdir -p /usr/local/bin
sudo install -o root -g root -m 0755 cri-dockerd /usr/local/bin/cri-dockerd
sudo install packaging/systemd/* /etc/systemd/system
sudo sed -i -e 's,/usr/bin/cri-dockerd,/usr/local/bin/cri-dockerd,' /etc/systemd/system/cri-docker.service
sudo systemctl daemon-reload
sudo systemctl enable cri-docker.service
sudo systemctl enable --now cri-docker.socket

It’s now time to install kubeadm: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

sudo apt install --yes apt-transport-https

curl -fsSL https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo gpg --dearmor -o /etc/apt/keyrings/kubernetes-archive-keyring.gpg

echo \
  "deb [signed-by=/etc/apt/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | \
  sudo tee /etc/apt/sources.list.d/kubernetes.list
  
sudo apt update
sudo apt install --yes kubelet kubeadm kubectl

# Disable Kubernetes auto-update
sudo apt-mark hold kubelet kubeadm kubectl

Initializing a cluster

At last, a Kubernetes cluster can be initialized: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/

The control plane endpoint cannot be easily changed after initialization. If you plan to add more nodes to this cluster, you should replace 127.0.0.1 with the private IP of your server, which you can check from your instance page. Or even better, create a domain name and set it to the private IP of your server, then use it as the control plane endpoint, so you can change it in the future.

sudo kubeadm init --control-plane-endpoint=127.0.0.1 --cri-socket=unix:///var/run/cri-dockerd.sock