When you add resources to your hand-rolled Kubernetes cluster, you'll need to do more work. In order to have nodes join in as you add them automatically via a scaling group, or manually via Infrastructure as code, you'll need to ensure that automatic registration of nodes is enabled via the --register-node flag. If  this flag is turned on, new nodes will attempt to auto-register themselves. This is the default behavior.

You can also join nodes manually, using a pre-vetted token, to your clusters. If you initialize kubeadm with the following token:

kubeadm init --token=101tester101 --kubernetes-version $(kubeadm version -o short)

You can then add additional nodes to your clusters with this command:

kubeadm join --discovery-token-unsafe-skip-ca-verification --token=101tester101:6443

Normally in a production install of kubeadm, you would not specify the token and need to extract it and store it from the kubeadm init command.