Kubeadm Setup

Abstract

The process for bringing up a bare-metal k8s cluster with kubeadm.

Kubeadm Setup#

kubeadm init issue

First Control Plane#

cert_key="$(kubeadm certs certificate-key)"
node_token="$(kubeadm token generate)"

kubeadm init --apiserver-advertise-address 192.168.1.50 \
    --apiserver-bind-port 6443 \
    --apiserver-cert-extra-sans '192.168.1.50,192.168.1.51,kcp01.socal.rr.com,kubernetes.default.svc.local,kubernetes' \
    --certificate-key "${cert_key}" \
    --control-plane-endpoint 'kcp01.socal.rr.com' --node-name 'kcp01' \
    --token "${node_token}" \
    --upload-certs
kubeadm init output

Your Kubernetes control-plane has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

Alternatively, if you are the root user, you can run:

export KUBECONFIG=/etc/kubernetes/admin.conf

You should now deploy a pod network to the cluster. Run “kubectl apply -f [podnetwork].yaml” with one of the options listed at: https://kubernetes.io/docs/concepts/cluster-administration/addons/

You can now join any number of the control-plane node running the following command on each as root:

kubeadm join kcp01.socal.rr.com:6443 --token "${node_token}" \
    --discovery-token-ca-cert-hash ${ca_cert_hash} \
    --control-plane --certificate-key "${cert_key}"

Please note that the certificate-key gives access to cluster sensitive data, keep it secret! As a safeguard, uploaded-certs will be deleted in two hours; If necessary, you can use “kubeadm init phase upload-certs –upload-certs” to reload certs afterward.

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join kcp01.socal.rr.com:6443 –token \({node_token} \ --discovery-token-ca-cert-hash \){ca_cert_hash}

Second Control Plane#

kubeadm join kcp01.socal.rr.com:6443 --token ${node_token} \
    --discovery-token-ca-cert-hash ${ca_cert_hash} \
    --control-plane --certificate-key ${cert_key}
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