Installing Charmed Kubernetes on Existing Machines

Machines that are provisioned without Juju can still be used for Juju deployments. This is known as a manual cloud and is described in the following Juju documentation:

https://juju.is/docs/juju/manual

In this guide, we will create a manual cloud with 3 existing machines. We will then deploy a minimal installation of Charmed Kubernetes to this cloud using the Kubernetes Core bundle.

<span class="p-notification__title">Note:</span>
<p class="p-notification__message">The default <a href="https://charmhub.io/charmed-kubernetes">Charmed Kubernetes</a> bundle is supported on manual clouds. However, it has significantly higher resource requirements (10+ machines) due to the focus on highly available components.</p>

What you will need

Ensure you have Juju 3.1 or greater installed on your management client. You will also need 3 existing machines installed with Ubuntu 22.04 (or equivalent). Your management client will need to be able to SSH to an administrative user on these machines.

Bootstrap the environment

Designate one of your existing machines to be a Juju controller for this manual cloud. Bootstrap the controller with the following:

juju bootstrap manual/<user>@<controller IP address> my-cloud

Juju will SSH to the specified IP address as the specified user and install all necessary requirements. When the controller is ready, create a model to house the Charmed Kubernetes deployment:

juju add-model my-model

Before starting the deployment, add the remaining existing machines to the Juju model with the following:

juju add-machine ssh:<user>@<machine IP address>

As before, Juju will SSH to the machine and install all necessary requirements. Repeat this step for as many machines as you wish Juju to use.

When complete, check the Juju model status to ensure at least two existing machines are running:

juju status

Deploy a minimal bundle

As mentioned, we are deploying a minimal installation of Charmed Kubernetes in this guide. The Kubernetes Core bundle deploys a single unit of easyrsa, etcd, and kubernetes-control-plane on one machine and a single unit of kubernetes-worker on another.

Deploy kubernetes-core to the Juju model as follows:

juju deploy kubernetes-core --map-machines=existing

<span class="p-notification__title">Note:</span>
<p class="p-notification__message">The "--map-machines" flag instructs Juju to use existing machines to satisfy placement directives defined in the budnle. Without this, Juju would attempt to provision new machines for this deployment. More information about machine mapping can be found in the <a href="https://juju.is/docs/juju/juju-deploy">Juju deploy</a> documentation.</p>

When complete, monitor the Juju model status until all workloads report active:

juju status

Next Steps

Now that you have a Charmed Kubernetes cluster up and running, check out the Operations guide for how to use it!