Setup a minimal Kubernetes cluster with Ansible

Requirments

You need to setup servers running the default Ubuntu 22.04 LTS cloud image and be able to ssh into them. The servers need to be able to communicate with each other.

The playbooks assume root access. If you can't login via root you need to configure become on the Ansible cli.

Copy the IPs of your servers into the hosts/inventory file. You need at least one IP for each: master, control_planes, worker.

Your inventory might look like this:

[master]
192.168.2.1

[control_planes]
192.168.2.2
192.168.2.3

[worker]
192.168.2.4
192.168.2.5
192.168.2.6

master is just the control-plane used to boostrap the k8s cluster with kubeadm.

Usage

Change into the ansible/ directory.

To prepare the Ubuntu servers for Kubernetes, run:

ansible-playbook -i hosts -u root prepare-ubuntu-k8s-nodes.yaml

As long as the playbook doesn't fail in the setup-containerd task, it is idempotent.

Now you can create a Kubernetes cluster with:

ansible-playbook -i hosts -u root create-k8s-cluster.yaml

This playbook is NOT idempotent. Don't run it twice.

If everything worked out, you can ssh into the master-node and run:

export KUBECONFIG=/etc/kubernetes/admin.conf
kubectl get nodes

Which should print something like this:

NAME   STATUS   ROLES           AGE   VERSION
c1     Ready    control-plane   20m   v1.27.3
c2     Ready    control-plane   18m   v1.27.3
c3     Ready    control-plane   18m   v1.27.3
w1     Ready    <none>          18m   v1.27.3
w2     Ready    <none>          18m   v1.27.3
w3     Ready    <none>          18m   v1.27.3

You now have bootstrapped a minimal but usable k8s-cluster.