Write a k0sctl.yaml file, and run k0sctl. This declarative tool connects to all nodes and deploys the cluster. It’s also used for updating the k0s version and adding or removing nodes.

• Write the k0sctl.yaml file
  • It very much helps to have a k0s.yaml file available for reference, generate one with k0s config create
  • We use dynamic mode so that we can subsequently configure the cluster with CRs rather than changing k0sctl.yaml and re-runing k0sctl apply
  • We need to include the DNS names and IP addresses of the nodes, as well as those of any load balancers, in the spec.api.sans list.
• k0sctl apply -c k0sctl.yaml
• Wait for all the nodes to come up
• Get a kubeconfig with k0sctl kubeconfig -c k0sctl.yaml and place it into ~/.kube/config on whatever machine you’re using to administer the cluster (your laptop, whatever)
• See pods starting with kubectl get pods -A etc
• It will automatically substitute environment variables like ${THIS_EXAMPLE}

You can change the k0sctl.yaml configuration or add new nodes there and re-apply.

Building the cluster for the first time took many tries #

You probably can’t go from nothing to a cluster without rebuilding it a few times. Some thoughts:

• Get a single node cluster working with a hand-built k0s.yaml (modified from a default one from k0s config create).
• Get a multi node cluster working with k0sctl and a k0sctl.yaml. This creates a k0s.yaml on each host. See one version of this in 𓁿 kubernasty/k0sctl.yaml
• Check k0s sysinfo to see any warnings or errors.
• See Destruction for details on tearing down the cluster.

An empty cluster #

At this point, your cluster is pretty barebons, running just a few containers like the cluster DNS server and other low level system containers. It lacks many normal features like:

• It has no LoadBalancer implementation
• It has no Ingress implementation
• It has no default storage provider

We’ll use Flux to install these components.