If you want to initialize a cluster with only one node, specify single master node in cluster configuration file:

cluster:
  ...
  nodes:
    master:
      instances:
      - id: 1
        ip: 10.10.64.5 # (1)!
        mac: "52:54:00:00:00:40" # (2)!

1. Static IP address. If omitted, the DHCP lease is requested.
2. Static MAC address. If omitted, the MAC address is generated.

Do not forget to remove (or comment out) the worker and load balancer nodes.

Apply the cluster:

kubitect apply --config single-node.yaml

Your master node now also becomes a worker node.